AC8C. Stay Current—Search for Habitable Planets

NASA’s Kepler mission (to find Earth size planets in the habitable zones of stars): see also PASS Kepler page, archive of Kepler News stories, and kepler.nasa.gov (Kepler education website). 

For the Exoplanet Transits investigation, data to generate a light curves for various exoplanets:

• images provided by the Zen Observatory, from their TrES-3 page.
• images of GJ 436b from Bareket Observatory (Israel) on 2010 Feb 20 (85 Mb) w/ finding chart.
• The MicroObservatory project exoplanet observations. Get Images > Image Archive > Other Worlds

2024-08-27. JWST found rogue worlds that blur the line between stars and planets. By Leah Crane, NewScientist. Excerpt: Astronomers have found six new worlds that look like planets, but formed like stars. These so-called rogue worlds are between five and 15 times the mass of Jupiter, and one of them may even host the beginnings of a miniature solar system. …From their observations, the researchers determined that planetary mass brown dwarfs make up about 10 per cent of the objects in NGC 1333. That is far more than expected based on models of star formation, so there may be extra processes, such as turbulence, that drive the formation of these rogue worlds. …One of the brown dwarfs is particularly unusual – it has a ring of dust around it just like the one that formed the planets in our solar system. At about five Jupiter masses, it is the smallest world ever spotted with such a ring, and it may mark the beginnings of a strange, scaled-down planetary system around a failed star…. Full article at https://www.newscientist.com/article/2445279-jwst-found-rogue-worlds-that-blur-the-line-between-stars-and-planets/.

2024-06-20. Could super-Earths or mini-Neptunes host life among the stars? By DANIEL CLERY, Science. Excerpt: Living on one of the seven Earth-size planets in the TRAPPIST-1 system would be strange…. Looming ominously in the sky is an enormous red star, prone to fiery outbursts and appearing several times bigger than the Sun. Hours of the day don’t exist; each planet is tidally locked to the star so that one side is forever scorchingly hot, the other eternally frozen. Along the margin dividing the day- and nightsides—the only place with a tolerable climate—a ceaseless wind blows and the star hangs on the horizon, in perpetual sunset. A short stroll into the dark side brings your planetary companions into view. Every few days one or more passes overhead like a floating lantern, larger than the Moon. …the quest to learn whether one of the TRAPPIST-1 planets could make a comfortable home for our imaginary observer has been an exercise in frustration. When the seven known planets around TRAPPIST-1 were revealed in 2017, they were …the best place to look for a habitable planet with JWST, NASA’s 2-year-old orbiting observatory. …JWST’s ability to peer into exoplanets’ atmospheres in the infrared, where life-friendly molecules such as water and carbon dioxide leave their fingerprints, is unique. …four of the seven are reckoned to sit in a habitable zone where liquid water could exist on their surfaces. …transits are a boon to observers, because if there is an atmosphere, some of the starlight will pass through it…selectively absorb the light at specific wavelengths, creating troughs in the starlight’s spectrum. Astronomers have used the technique to find evidence for carbon dioxide, methane, and water in the atmospheres of large, hot, uninhabitable planets. …By the end of its third year, JWST will have lavished 175 hours of observing time on TRAPPIST-1. However, JWST has yet to find any firm evidence of an atmosphere around TRAPPIST-1’s planets…. Full article at https://www.science.org/content/article/could-super-earths-mini-neptunes-host-life-among-stars.

2024-06-03. ASTRONOMERS DISCOVER NEW EARTH-SIZE WORLD ONLY 40 LIGHT-YEARS AWAY. By ARIELLE FROMMER, Sky & Telescope. Excerpt: In the search for planets around other stars, astronomers often seek worlds that are most like our own. The discovery of Gliese 12b — the closest, transiting, temperate, Earth-size planet found to date — promises possibilities for understanding how terrestrial planets become habitable. Gliese 12b orbits a cool red dwarf star around 40 light-years away — practically neighborly compared to other exoplanets — with a period of 12.8 days. Its distance from its host star means that its surface might be temperate enough for life, with a temperature of 107°F (42°C). …Gliese 12b was initially detected by NASA’s Transiting Exoplanet Survey Satellite (TESS), a mission that searches for changes in stellar brightness and records transits that occur when a planet passes in front of its host star. …Red dwarf stars, or M stars, have small masses and radii and low luminosities, which means any planets orbiting in the “habitable zone” (the orbital space where a rocky planet might host liquid water on its surface) transit more deeply and more often. Gliese 12b’s orbit is a mere 0.07 astronomical unit from its host star. Yet even though it would be well inside Mercury’s orbit around the Sun, its star’s low luminosity means the planet could be comfortable for life…. Full article at https://skyandtelescope.org/astronomy-news/astronomers-discover-new-earth-size-world-only-40-light-years-away/.

2024-04-05. Tatooine, Trisolaris, Thessia: Sci-Fi Exoplanets Reflect Real-Life Discoveries. [https://eos.org/articles/tatooine-trisolaris-thessia-sci-fi-exoplanets-reflect-real-life-discoveries] By Kimberly M. S. Cartier, Eos/AGU. Excerpt: Astronomers have discovered more than 5,000 extrasolar planets since the 1995 discovery of 51 Pegasi b. When the discoveries started pouring in, astronomers quickly realized that few exoplanets resembled anything in the solar system. …A new study led by Puranen examined how the discovery of real exoplanets has influenced portrayals of fictional ones. The researchers showed that as scientists discovered that real-life exoplanets rarely resembled Earth, sci-fi exoplanets became less Earth-like, too. …The analysis showed that “fictional exoplanets from after the real-life discovery of exoplanets were less likely to have intelligent native life and less likely to have established populations of non-native humans,” Puranen said. Sci-fi exoplanets became less Earth-like and more likely to feature nonintelligent native biospheres. These results were published in the Journal of Science Communication in March. …Star Wars familiarized folks with Tatooine decades before the 2005 discovery of HD 202206 c, the first known exoplanet orbiting two Sun-like stars….

2023-11-29. Astronomers stunned by six-planet system frozen in time. [https://www.science.org/content/article/astronomers-stunned-six-planet-system-frozen-time] By DANIEL CLERY, Science. Excerpt: Astronomers have discovered a highly unusual planetary system …six planets, all bigger than Earth but smaller than Neptune, a variety that is absent in our Solar System but common across the Milky Way. Moreover, all of the planets orbit in rhythmic harmony, which suggests the system has remained undisturbed since its formation billions of years ago. The brightness of the star, its relative proximity to Earth, and its six orbiting oddities could make the system a perfect laboratory for studying the formation of these planets, known as sub-Neptunes. …the study, published today in Nature. The planets’ orbits are all tighter than Mercury’s. …a mysterious [size] gap persists: Planets between 1.5 and two Earth diameters seem almost entirely absent and astronomers are eager to know why. …The new system’s discovery involved two space telescopes, multiple ground-based ones, and more than 3 years of detective work by dozens of astronomers. The hunt began in 2020 …from NASA’s Transiting Exoplanet Survey Satellite (TESS), which looks for dips in a star’s brightness caused by planets passing in front. He noticed intriguing but inconclusive dips associated with HD 110067, a Sun-like star just 100 light-years from Earth. …Subsequent observations by the European Space Agency’s Characterising Exoplanet Satellite (CHEOPS) identified a third planet, with an orbital period of 20.5 days. …The orbits of the three known planets showed a 3/2 resonance between each neighboring pair: For every three times the inner planet orbits, the outer neighbor orbits twice. On a hunch that others could also be in resonance, Luque’s team looked for additional hypothetical planets with resonances of 2/1, 3/2, 4/3, and so on. A fourth planet, in a 3/2 resonance and with an orbital period of 30.8 days, perfectly matched two of the transits. …the researchers were able to show how the two remaining transits would fit well with planets orbiting every 41.1 days and 54.7 days. Each of those planets is in a 4/3 resonance with its inner neighbor…. See also articles in The Washington Post, The New York Times, and Sky & Telescope.

2023-10-05. James Webb telescope makes ‘JuMBO’ discovery of planet-like objects in Orion. [https://www.bbc.com/news/science-environment-66974738] By Jonathan Amos, The Guardian. Excerpt: Jupiter-sized “planets” free-floating in space, unconnected to any star, have been spotted by the James Webb Space Telescope (JWST). What’s intriguing about the discovery is that these objects appear to be moving in pairs. Astronomers are currently struggling to explain them. The telescope observed about 40 pairs in a fabulously detailed new survey of the famous Orion Nebula. They’ve been nicknamed Jupiter Mass Binary Objects, or “JuMBOs” for short. …”Gas physics suggests you shouldn’t be able to make objects with the mass of Jupiter on their own, and we know single planets can get kicked out from star systems. But how do you kick out pairs of these things together? Right now, we don’t have an answer. It’s one for the theoreticians,” the European Space Agency’s (Esa) senior science adviser told BBC News….

2023-08-14. Subsurface Oceans Could Boost Exoplanet Habitability. [https://eos.org/articles/subsurface-oceans-could-boost-exoplanet-habitability] By Javier Barbuzano, Eos/AGU. Excerpt: A group of researchers led by planetary scientist Lujendra Ojha of Rutgers University crunched the numbers to reveal that our galaxy is likely brimming with planets hosting subsurface oceans like those on Enceladus, Europa, and Ganymede. “Before we started to consider this subsurface water, it was estimated that around one rocky planet [orbiting] every 100 stars would have liquid water,” Ojha said. “The new model shows that if the conditions are right, this could approach one planet per star.”…

2023-07-24. Webb Detects Water Vapor in Rocky Planet-Forming Zone. [https://www.nasa.gov/feature/goddard/2023/webb-detects-water-vapor-in-rocky-planet-forming-zone] By NASA. Excerpt: Water is essential for life as we know it. However, scientists debate how it reached the Earth and whether the same processes could seed rocky exoplanets orbiting distant stars. New insights may come from the planetary system PDS 70, located 370 light-years away. The star hosts both an inner disk and outer disk of gas and dust, separated by a 5 billion-mile-wide (8 billion kilometer) gap, and within that gap are two known gas-giant planets. New measurements by NASA’s James Webb Space Telescope’s MIRI (Mid-Infrared Instrument) have detected water vapor in the system’s inner disk, at distances of less than 100 million miles (160 million kilometers) from the star – the region where rocky, terrestrial planets may be forming. (The Earth orbits 93 million miles from our Sun.) This is the first detection of water in the terrestrial region of a disk already known to host two or more protoplanets. “We’ve seen water in other disks, but not so close in and in a system where planets are currently assembling. We couldn’t make this type of measurement before Webb,” said lead author Giulia Perotti of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany…. See also Nature article, Water in the terrestrial planet-forming zone of the PDS 70 disk.

2023-07-12. Aomawa Shields on Searching For Life in Space, and at Home. [https://www.kqed.org/forum/2010101893676/aomawa-shields-on-searching-for-life-in-space-and-at-home] KQED podcast. Excerpt: Does it matter if life exists on another planet? To UC Irvine astrobiologist Aomawa Shields it matters in the same way that a mountain matters and screams to be climbed: not knowing is unbearable. Shields has devoted her career to studying the climate and habitability of exoplanets to further the search for extraterrestrial life. She’s also one of very few Black women in a field dominated by white men and a classically trained actor. We talk to her about her journey as a scientist and an artist and her new book “Life on Other Planets: A Memoir of Finding My Place in the Universe.”… See also TED Talk, How we’ll find life on other planets.

2023-06-22. Nearby Volcano Planet Likely Fueled by Tidal Heating. [https://eos.org/articles/nearby-volcano-planet-likely-fueled-by-tidal-heating] By Javier Barbuzano, Eos/AGU. Excerpt: An unusual planetary dance has produced an Earth-sized exoplanet brimming with volcanoes, likely furnished with an atmosphere, and maybe even containing water on its surface. Astronomers discovered this odd world orbiting a red dwarf star right in our galactic neighborhood—just 90 light-years away. The exoplanet, known as LP 791-18 d, orbits a red dwarf already known to host two other planets: LP 791-18 b, a scorched, rocky world orbiting extremely close to the star, and LP 791-18 c, a sub-Neptune 7 times more massive than Earth made of gas or icy material. The finding comes after a group of researchers led by astrophysicist Björn Benneke of the Université de Montréal in Canada used NASA’s recently retired Spitzer Space Telescope to take a closer look at the system….

2023-05-08. Webb Looks for Fomalhaut’s Asteroid Belt and Finds Much More. [https://www.nasa.gov/feature/goddard/2023/webb-looks-for-fomalhaut-s-asteroid-belt-and-finds-much-more] By NASA. Excerpt: Astronomers used NASA’s James Webb Space Telescope to image the warm dust around a nearby young star, Fomalhaut, in order to study the first asteroid belt ever seen outside of our solar system in infrared light. But to their surprise, the dusty structures are much more complex than the asteroid and Kuiper dust belts of our solar system. Overall, there are three nested belts extending out to 14 billion miles (23 billion kilometers) from the star; that’s 150 times the distance of Earth from the Sun. The scale of the outermost belt is roughly twice the scale of our solar system’s Kuiper Belt of small bodies and cold dust beyond Neptune. The inner belts – which had never been seen before – were revealed by Webb for the first time. …The team’s results are being published in the journal Nature Astronomy. See also New York Times article….

2023-04-28. Exoplanets May Support Life in the Terminator Zone. [https://eos.org/articles/exoplanets-may-support-life-in-the-terminator-zone] By lakananda Dasgupta, Eos/AGU. Excerpt: A new study finds that the intersection between a searing dayside and a freezing nightside could be habitable. The results were presented at AGU’s Fall Meeting 2022 and were published recently in The Astrophysical Journal. The finding could widen the search for habitable planets in the universe….

2023-04-10. Hydrogen May Push Some Exoplanets off a Cliff. [https://eos.org/articles/hydrogen-may-push-some-exoplanets-off-a-cliff] By Julie Nováková, Eos/AGU. Excerpt: With the discovery of more than 5,000 confirmed exoplanets, astronomers understand more and more about what kinds of planets exist and why. But the data deluge has also thrown into relief the kinds of planets that don’t seem to exist. In particular, there is a steep decrease in the abundance of planets larger than approximately 3 Earth radii, a pattern nicknamed the “radius cliff.” …new research published in the Planetary Science Journal has shown how high-pressure, high-temperature chemical reactions might put a cap on planet growth. …Missions like NASA’s Kepler and Transiting Exoplanet Survey Satellite have revealed a curious mystery: Planets 3 times Earth’s size are about 10 times more abundant than planets that are only slightly larger. …In a first-of-its-kind experiment, researchers placed a thin foil of pressed metal oxides into tiny presses called diamond anvil cells …to study what happens under the high-temperature, high-pressure conditions expected at the atmosphere–rocky core interface on sub-Neptunes. …hydrogen not only freed iron from its oxides but also reacted with it, forming an alloy. …That ability to sequester hydrogen, mostly as the iron-hydrogen alloy sinking into the metallic part of the core, could limit growth of an exoplanet’s atmosphere, resulting in the observed radius cliff….

2023-01-31. “Hot Jupiter” Is in a Possible Death Spiral. [https://eos.org/articles/hot-jupiter-is-in-a-possible-death-spiral] By Damond Benningfield, Eos/AGU. Excerpt: Kepler’s first exoplanet is migrating toward its star, an evolved subgiant that is much bigger than first thought. …Kepler-1658b is the first inspiraling planet discovered around an “evolved” star—one that has moved out of its prime life. The star—Kepler-1658—is about 1.5 times the mass of our Sun and has expanded to almost 3 times the Sun’s diameter in its late stages of life, earning it the designation of subgiant. Should Kepler-1658b maintain its current path, it will meet its fate in about 2.5 million years. …Early in its mission, Kepler recorded such dips from Kepler-1658. However, astronomers had initially cataloged the star as belonging to the main sequence—stars like the Sun that are still burning the hydrogen in their cores. …Kepler-1658b was discarded as a false positive and forgotten about. …That is, until Chontos began looking at vibrations on the surfaces of stars in the Kepler catalog…—a technique known as asteroseismology—revealed details about the stars’ interiors. …they showed that the star was much farther along in life than expected and hence about 3 times bigger. That meant the transiting planet was 3 times larger as well, making it big enough and bright enough to contribute to the system’s overall brightness when it wasn’t eclipsed by the star. “Suddenly, a close-in hot Jupiter made sense,” Chontos said. “That discovery was completely accidental.”…

2023-01-15. Webb Telescope Confirms Earth-size Exoplanet, Tries to Sniff Its Air. [https://skyandtelescope.org/astronomy-news/webb-telescope-confirms-earth-size-exoplanet-tries-to-sniff-air] By Monica Young, Sky & Telescope. Excerpt: The James Webb Space Telescope has confirmed its first exoplanet, a rocky Earth-size planet, and attempted to take the measure of its atmosphere. …Although roughly Earth-like in size, this world is nevertheless completely uninhabitable, roasting in its four-day orbit around its middle-aged red dwarf star. …while they can match the data with an atmosphere dominated by carbon dioxide, those data are also consistent with a completely airless world. Zero atmosphere for a planet several hundred degrees warmer than Earth wouldn’t be a great surprise, especially around the type of star known for its atmosphere-stripping flares….

2023-01-02. Astronomy Modeling with Exoplanets course. [https://www.modelinginstruction.org/pd/upcoming-workshops-2/2023-spring-distance-learning-courses/] By the American Modeling Teachers Association. Excerpt: This course gives teacher participants a 45-hour distance learning experience that will ground them in the use of the Modeling Method of Instruction. This course follows AMTA’s initial face-to-face Astronomy Modeling Workshop in 2019 and utilizes newly updated curriculum resources that focus on the modern-day scientific pursuit of discovering and exploring planets around other star systems: exoplanets. …participants …develop models of space and time that enable them to locate objects and map space from the perspective of Earth …examine motion and forces in order to develop a generalizable model of orbital motion. …construct both particle and wave models of light as a mode of energy transfer (and information transfer) via radiation. …develop a model of cosmic evolution, to better understand the history and fate of our universe …consider the probability of life elsewhere in the universe, on exoplanets. …develop skills and knowledge in observational astronomy, image acquisition, stellar photometry, data and image analysis, and how telescopes work …access remote telescopes and collaborate with professional exoplanet astronomers in their own exoplanet observations….

2022-09-01. Webb telescope takes its first direct image of an exoplanet. [https://www.science.org/content/article/webb-telescope-takes-its-first-direct-image-exoplanet] By Daniel Clery, Science Magazine. Excerpt: A research team analyzing early data from the James Webb Space Telescope has revealed the instrument’s initial images of a planet beyond our Solar System, a success that closely follows last week’s unveiling of Webb’s first measurements from the atmosphere of a different exoplanet. The newly imaged young gas giant, seven times the mass of Jupiter, is captured still glowing hot after its formation. The planet’s infrared emissions traveled 350 light-years before the photons were gathered by Webb’s gold-plated mirrors. In a paper posted today on the arXiv preprint server, the Webb astronomers exhibit several images of the planet, called HIP 65426 b, at a range of wavelengths (shown in insets, above) that have heretofore been invisible to Earthbound telescopes because of our planet’s infrared-blocking atmosphere. …the high quality of these first images bodes well for its discovery of new, even smaller exoplanets, down to the size of Saturn or even Neptune—ice giants that have never been directly observed outside our Solar System. Researchers hope Webb’s images will help them understand how and where such planets form in the disks of dust and gas around newborn stars.…

2022-08-25. Carbon dioxide detected around alien world for first time. [https://www.science.org/content/article/carbon-dioxide-detected-around-alien-world-first-time] By Daniel Clery, Science Magazine. Excerpt: Astronomers have found carbon dioxide (CO₂) in the atmosphere of a Saturn-size planet 700 light-years away—the first unambiguous detection of the gas in a planet beyond the Solar System. The discovery, made by the James Webb Space Telescope, provides clues to how the planet formed. The result also shows just how quickly Webb may identify a spate of other gases, such as methane and ammonia, which could hint at a planet’s potential habitability for life. …The Webb telescope is sensitive to infrared wavelengths of light that are mostly blocked by Earth’s atmosphere. …the infrared sensitivity is also critical for researchers…. When an exoplanet’s orbit takes it in front of its star, some of the starlight passes through the planet’s atmosphere and carries fingerprints of its composition. The atmospheric gases absorb specific wavelengths of light, which show up as dips in brightness when the starlight is spread out into a spectrum. For most gases of interest, the dips occur at infrared wavelengths.…

2022-04-13. Discovery Alert: A Flood of New Planets, Plus Hint of an ‘Exomoon’. By Pat Brennan, NASA’s Exoplanet Exploration Program. Excerpt: Data from NASA’s now-retired Kepler Space Telescope reveals an eclectic assortment of new planets and planetary systems that promises to deepen understanding of how exoplanets form. Some of the newly-discovered planets might make tempting targets for the James Webb Space Telescope, now being fine-tuned for its first observations this summer. The Webb telescope is expected to search for signs of atmospheres around some exoplanets, and potentially determine some of the gases and molecules present. This raft of new planets also helped push NASA’s tally of confirmed exoplanets past the 5,000 mark in March 2022. …Combing through Kepler data also revealed another potentially significant find: a possible exomoon. …The new possible exomoon, Kepler-1708 b-i, would be very large for a moon, about 2.6 times as big around as Earth. It would be orbiting a confirmed Jupiter-sized planet, itself in orbit around a Sun-like star more than 5,400 light-years away from Earth. It’s the second “unexpectedly large” exomoon candidate identified by astronomers; the first, Kepler-1625 b-i, was revealed in 2018 – a possible Uranus-sized moon also orbiting a Jupiter-sized planet. … [https://exoplanets.nasa.gov/news/1704/discovery-alert-a-flood-of-new-planets-plus-hint-of-an-exomoon/]

2022-04-11. Giant Planet’s Formation Caught in Action. By Jure Japelj, Eos/AGU. Excerpt: Astronomers took a direct image of a massive protoplanet embedded in a protoplanetary disk. The system provides strong evidence for an as-yet-unconfirmed theory of planet formation. …Jupiter-class gas giants on far-flung orbits have challenged what is known as the standard formation scenario. Scientists converged on the scenario that our solar system’s giant planets formed via accretion within the gaseous protoplanetary disk. Rocky planetary cores fed on pebbles or planetesimals, and once the cores reached a certain mass, they began gobbling up the surrounding gas, rapidly becoming giant planets. But that process works only when planets form relatively close to their host stars—the gas giants found on wide orbits would not have had time to grow a sufficiently massive core before the gaseous disk dissipated. The unstable disk model is one of several alternative models suggesting that a massive and gravitationally unstable protoplanetary disk could fragment into dense clumps, directly giving birth to wide-orbiting planets. …Now, a team of scientists has made a discovery that might have been just the evidence the community has been waiting for. The team imaged a massive protoplanet orbiting the star AB Aurigae at about 93 times the distance between Earth and the Sun. Scientists caught the planet in an early stage of formation, still embedded in a protoplanetary disk. The properties of both the planet and the disk match well the predictions of the unstable disk model. The study was published in Nature Astronomy.… [https://eos.org/articles/giant-planets-formation-caught-in-action]

2022-04-02. Imagine Another World. Now Imagine 5,000 More. By Becky Ferreira, The New York Times. Excerpt: NASA recently announced that it had detected more than 5,000 exoplanets, so we asked astronomers, actors and an astronaut to share their favorite worlds orbiting distant stars.… [https://www.nytimes.com/2022/04/02/science/nasa-exoplanets-5000.html]

2021-12-02. Metal Planet Orbits Its Star Every 7.7 Hours. By Adam Mann, The NewYork Times. Excerpt: Astronomers call it a “super-Mercury” and think it holds clues to how planets form close in to their stars. …Because it sits so close to its parent, one side of GJ 367 b likely always faces the blazing star. Its dayside temperatures should soar toward 2,700 degrees Fahrenheit, hot enough to melt rock and metal, making it a potential lava world… [https://www.nytimes.com/2021/12/02/science/iron-exoplanet-super-mercury.html]

2021-11-06. Star System With Right-Angled Planets Surprises Astronomers. By Jonathan O’Callaghan, The New York Times. Excerpt: Two planets orbit the poles while another revolves around the star’s equator, suggesting a mysterious, undetected force.… [https://www.nytimes.com/2021/11/06/science/perpendicular-planets-star-system.html] See also A Mysterious, Undetected Force Is Influencing the Orbit of Two Alien Worlds and the paper — The Rossiter–McLaughlin effect revolutions: an ultra-short period planet and a warm mini-Neptune on perpendicular orbits.

2021-10-13. Astronomers Found a Planet That Survived Its Star’s Death. By Becky Ferreira, The New York Times. Excerpt: When our sun enters its death throes in about five billion years, it will incinerate our planet and then dramatically collapse into a dead ember known as a white dwarf. But the fate of more distant planets, such as Jupiter or Saturn, is less clear. On Wednesday in the journal Nature, astronomers reported observing a tantalizing preview of our solar system’s afterlife: a Jupiter-size planet orbiting a white dwarf some 6,500 light years from here. Known as MOA-2010-BLG-477Lb, the planet occupies a comparable orbit to Jupiter. The discovery not only offers a glimpse into our cosmic future, it raises the possibility that any life on “survivor” worlds may endure the deaths of their stars. …“The fate of our solar system is likely to be similar to MOA-2010-BLG-477Lb,” he added in an email. “The sun will become a white dwarf, the inner planets will be engulfed, and the wider-orbit planets like Jupiter and Saturn will survive.”… [https://www.nytimes.com/2021/10/13/science/white-dwarf-planet.html]

2021-09-28. This May Be the First Planet Found Orbiting 3 Stars at Once. Source: By Jonathan O’Callaghan, The New York Times. Excerpt: It’s called a circumtriple planet, and evidence that one exists suggests that planet formation is less unusual than once believed. …GW Ori is a star system 1,300 light years from Earth in the constellation of Orion. It is surrounded by a huge disk of dust and gas, a common feature of young star systems that are forming planets. But fascinatingly, it is a system with not one star, but three. …GW Ori’s disk is split in two, almost like Saturn’s rings if they had a massive gap in between. …Scientists have been trying to explain what is going on there. Some hypothesized that the gap in the disk could be the result of one or more planets forming in the system. …Now the GW Ori system has been modeled in greater detail, and researchers say a planet — a gassy world as massive as Jupiter — is the best explanation for the gap in the dust cloud. Although the planet itself cannot be seen, astronomers may be witnessing it carve out its orbit in its first million years of its existence.… [https://www.nytimes.com/2021/09/28/science/triple-sun-planet.html]

2021-07-26. – Articles in Eos/AGU:  Unveiling the Next Exoplanet Act, by Heather Goss. Excerpt: …our August issue is all about exoplanets—what we know and what awaits us over the launch horizon. Who gets the first peek through James Webb Space Telescope (JWST)? In March, the proposals selected for the first observing cycle were announced. Meet the slate of scientists who will be pointing the telescope at other worlds, and read what they hope to learn in “Overture to Exoplanets.” …In “The Forecast for Exoplanets Is Cloudy but Bright,” we learn the immense challenge posed by exoplanet atmospheres, when researchers are still struggling to understand the complex dynamics of clouds on our own planet. …And in “Exoplanets in the Shadows,” we look at the rogues, the extremes, and a new field being coined as necroplanetology. See also Oddballs of the Exoplanet Realm. 

2021-06-21. [https://eos.org/articles/gap-in-exoplanet-size-shifts-with-age] – Gap in Exoplanet Size Shifts with Age. Source: By Katherine Kornei, Eos/AGU. Excerpt: Smaller planets are scarcer in younger systems and larger planets are lacking in older systems, according to new research that analyzed hundreds of exoplanets. …Planets just a bit larger than Earth appear to be relatively rare in the exoplanet canon. A team has now used observations of hundreds of exoplanets to show that this planetary gap isn’t static but instead evolves with planet age—younger planetary systems are more likely to be missing slightly smaller planets, and older systems are more apt to be without slightly larger planets. This evolution is consistent with the hypothesis that atmospheric loss—literally, a planet’s atmosphere blowing away over time—is responsible for this so-called “radius valley,” the researchers suggested….

2020-11-05. Earth-size Planets are Common, Kepler Retrospective Finds. Sky and Telescope Magazine. Excerpt: …NASA’s Kepler telescope was retired a few years ago, but ongoing analyses of its data, both by professional astronomers and citizen scientists, are still producing new results. …Kepler has found more than 2,600 exoplanets (and counting). Now, an international collaboration led by Steve Bryson, a researcher at NASA Ames, has announced a refined estimate. The team, including NASA scientists, SETI researchers, academics, former-Keplerites, and other planet hunters, performed a statistical analysis that combined Kepler’s planet catalog and stellar data from the European Space Agency’s Gaia observatory. They found that about half of the Sun-like stars in our galaxy could have a rocky planet in their habitable zones. …The study, soon to be published in The Astronomical Journal, predicts that there are at least 300 million habitable-zone rocky worlds in the Milky Way. A handful of these are within a few light-years of Earth. This result assumes that the section of the sky Kepler monitored for four years is representative of the whole galaxy…. [https://skyandtelescope.org/astronomy-news/kepler-retrospective-earth-like-planets-common/] See also The New York Times article https://www.nytimes.com/2020/11/05/science/astronomy-exoplanets-kepler.html

2020-04-20. The Case of the Disappearing Exoplanet. By Robin George Andrews, New York Times. Excerpt: Humanity’s growing tally of exoplanets — worlds seen orbiting other stars — stands at 4,151. Most were found indirectly, as they passed in front of their stars and cast a telltale shadow, or as they caused their star to wobble as they swung around it. Only 50 have been directly imaged through a telescope. Directly imaging an exoplanet was first achieved in two discoveries announced simultaneously in 2008. …a solitary planet dancing around the star Fomalhaut was spotted by the Hubble Space Telescope. Fomalhaut b, as the latter was named, appeared to be a colossal world, potentially as massive as three Jupiters, zipping along the inner edge of a giant doughnut of debris. … András Gáspár, an astronomer at the University of Arizona, was looking at Hubble’s images of the Fomalhaut system taken up through 2014, on the off chance that someone missed something. To his surprise, Fomalhaut b was nowhere to be found in 2014…. [https://www.nytimes.com/2020/04/20/science/fomalhaut-exoplanet-asteroid.html] 

2020-02-26. This rainy exoplanet could be ripe for life. By Daniel Clery. Science Magazine. Excerpt: A nearby exoplanet with rainclouds in its atmosphere may have habitable conditions at its surface, researchers report today. The planet, dubbed K2-18b, is 124 light-years away and 2.6 times the radius of Earth. Last year, astronomers detected clouds of liquid water in the planet’s hydrogen-rich atmosphere, a first for such a small planet. [https://www.sciencemag.org/news/2019/09/hints-rain-clouds-found-small-alien-world] …Now, a team of researchers in the United Kingdom describe in The Astrophysical Journal Letters how they calculated a range of possible atmospheres for the planet, based on its mass, size, and previously measured spectra of light that passed from K2-18b’s star through its atmosphere. (Molecules in the planet’s atmosphere absorb certain frequencies of light, so if the starlight passes through it on its way to Earth, the light’s spectrum can reveal those molecules.) They then used those possibilities to limit what conditions could exist in the planet’s interior. Their conclusion: The heart of K2-18b could be anything from a ball of almost pure iron with a hefty hydrogen atmosphere, to something more Neptune-like, to a water world with a lighter atmosphere and ocean conditions similar to Earth…. [https://www.sciencemag.org/news/2020/02/rainy-exoplanet-could-be-ripe-life] 

2020-01-10. A teenager discovered a new planet on the third day of his NASA internship. By Lateshia Beachum, The Washington Post. [https://www.washingtonpost.com/technology/2020/01/10/teenager-discovered-new-planet-third-day-his-nasa-internship/] Excerpt: Most people sit through countless orientations on the first few days of their job, but one teen discovered a planet — on his third day. Wolf Cukier, 17, of Scarsdale, N.Y., had wrapped up his junior year of high school when he headed off to intern in the summer at NASA’s Goddard Space Flight Center in Greenbelt, Md., where he discovered a planet orbiting two stars. The planet, now known as TOI 1338 b, is nearly seven times as large as Earth and has two stars — one that’s about 10 percent more massive than our sun and another only a third of the sun’s mass and less bright, according to NASA [https://www.nasa.gov/feature/goddard/2020/nasa-s-tess-mission-uncovers-its-1st-world-with-two-stars]. …Cukier had a framework of what to look for based on his exploration of the Planet Hunters TESS citizen science project [https://www.zooniverse.org/projects/nora-dot-eisner/planet-hunters-tess], which allows people to comb through TESS data and categorize star systems, he said….

2019-09-11. Water found for first time on potentially habitable planet. By Pallab Ghosh, BBC News. [https://www.bbc.com/news/science-environment-49648746] Excerpt: Astronomers have for the first time discovered water in the atmosphere of a planet orbiting within the habitable zone of a distant star. The finding makes the world – which is called K2-18b – a plausible candidate in the search for alien life. …Details were published in the scientific journal Nature Astronomy [https://www.nature.com/articles/s41550-019-0878-9]. …K2-18b is 111 light-years – about 650 million million miles – from Earth, too far to send a probe. …The team behind the discovery looked through the planets discovered by the Hubble Space Telescope between 2016 and 2017. The researchers determined some of the chemicals in their atmosphere by studying the changes to the starlight as the planets orbited their suns. The light filtered through the planets’ atmospheres was subtly altered by the composition of the atmosphere.Only K2-18b revealed  the molecular signature of water, which is a vital ingredient for life on Earth. Computer modelling of the data suggested that up to 50% of its atmosphere could be water…. 

2019-07-29. NASA’s TESS Satellite Spots ‘Missing Link’ Exoplanets. By Dennis Overbye, New York Times. [https://www.nytimes.com/2019/07/29/science/nasa-tess-exoplanets-astronomy.html] See also Newly discovered exoplanet trio could unravel the mysteries of super-Earth formation in Science Magazine [https://www.sciencemag.org/news/2019/07/newly-discovered-exoplanet-trio-could-unravel-mysteries-super-earth-formation] F Excerpt: NASA’s new planet-hunting spacecraft, the Transiting Exoplanet Survey Satellite, is now halfway through its first tour of the nearby universe. It has been looking for worlds that might be fit for you, me or some other form of life, and as usual, nature has been generous in its rewards. Since its launch in April 2018, TESS has already discovered 21 new planets and 850 more potential worlds that have yet to be confirmed, all residing within a few dozen light years of the sun and our own solar system, according to George Ricker, an M.I.T. researcher who heads the TESS project. So far, he said, TESS “has far exceeded our most optimistic hopes.” …Some of the discoveries generating the most excitement among the TESS crew were three new worlds that orbit a dim red dwarf star only 73 light-years from here in the southern constellation Pictor. The system goes by the name TOI-270, for Tess Object of Interest. …The outer two planets are “sub-Neptunes,” each slightly more than twice the size of the Earth, and with masses at least five times greater, according to models. (Neptune is about four times bigger than Earth, and 17 times as massive.) The innermost exoplanet is a “Super Earth,” about 1.2 times the size of our home world….  

2019-04-04. Astronomers spy an iron planet stripped of its crust around a burned-out star. By Daniel Clery, Science Magazine. [https://www.sciencemag.org/news/2019/04/astronomers-spy-iron-planet-stripped-its-crust-around-burned-out-star] Excerpt: In a glimpse of what may be in store for our own solar system, astronomers have discovered what appear to be the shattered remains of a planet orbiting a white dwarf, the burned-out ember of a star like our sun. If the team’s calculations are correct, the orbiting object may be the iron core of a small planet that had its outer layers ripped off by the white dwarf’s intense gravity. Although astronomers know of thousands of exoplanets in the Milky Way, they struggle to see anything much smaller than Earth. The new object is by far the smallest, more of an asteroid than a planet. …Finding the planetesimal, 400 light-years from Earth, wasn’t easy.  …Most exoplanets can’t be seen directly, but are found when they cast a shadow crossing the face of their star or when they tug their star back and forth with the force of their gravity. Manser’s team…picked apart the light coming from the disk to see its spectrum of frequencies and zoomed in on three bright spectral lines produced by calcium ions, which act as a flag for the gas circulating in the disk. …his team…saw that the two peaks in each calcium line rose and fell in opposition to each other every 2 hours like clockwork. “It was a really exciting discovery,” Manser says. …this is the signature of a planetesimal orbiting the star. …the calcium lines are not from the planetesimal itself, but from a cloud of gas that surrounds it, either because it is being battered by disk debris or because radiation from the star causes it to emit gas. As that gas cloud follows the planetesimal in its orbit, it boosts one emission peak while moving toward Earth and, an hour later, the other peak while moving away….  

2019-03-05. The first planet Kepler spotted has finally been confirmed 10 years later. By Lisa Grossman, Science News.  [https://www.sciencenews.org/article/first-planet-kepler-finally-confirmed-10-years-later] Excerpt: A decade after being found, the first exoplanet candidate spotted by the Kepler space telescope has been confirmed as a real world. The planet orbits a star initially dubbed KOI 4, for Kepler Object of Interest 4 (KOIs 1 through 3 were known before Kepler launched in March 2009). …The Kepler team originally thought the star was about 1.1 times the width of the sun, which would make the planet about the size of Neptune. But then astronomers saw a second dip in starlight as the world passed behind the star, called a secondary eclipse. That second dip shouldn’t be visible for such a small planet, so the exoplanet candidate was dismissed as a false alarm. …KOI 4 is actually about three times the width of the sun, meaning its planet would be about three times as large as first estimated — or a bit larger than Jupiter, the team found. That’s big enough for the world to block enough starlight that Kepler would notice that secondary eclipse, Chontos said March 5 in a presentation at NASA’s Kepler & K2 science conference in Glendale, Calif. After the findings were double checked by astronomers using ground-based telescopes, the star was renamed Kepler 1658, and the planet Kepler 1658b, adding the system to Kepler’s long list of discoveries. “It feels really cool to have that first planet there,” Chontos said….

2019-01-14. Modeling the Climates of Worlds Beyond Earth. By Katherine Kornei, Eos/AGU. [https://eos.org/articles/modeling-the-climates-of-worlds-beyond-earth]  Excerpt: Climate modeling isn’t limited just to planet Earth anymore. In recent decades, researchers have begun modeling the climates of other planets in the solar system and are now simulating conditions on faraway worlds orbiting other stars in the Milky Way galaxy. …There’s no shortage of planets to study: Nearly 4,000 extrasolar planets (exoplanets) have already been found using such instruments as the Kepler Space Telescope. The team for NASA’s Transiting Exoplanet Survey Satellite (TESS), which was just launched last year, announced the discovery of its third exoplanet at the AAS meeting last week. And an increasing number of worlds are being found that resemble our home planet in size, Shields said. “We are now in the Earth-sized regime.” …Shields is also studying the climatic effects of ice on exoplanets. Here on Earth, the majority of the sunlight that strikes the planet’s surface is in the form of visual light, which ice effectively reflects. But planets orbiting smaller, cooler stars known as M dwarfs—which are believed to be far more common in the Milky Way galaxy than Sun-sized stars—are bathed mostly in infrared light, which ice readily absorbs. As a result, planets orbiting M dwarfs were less likely to experience global ice coverage (i.e., a “snowball” stage), the researchers showed….

2019-01-07. Another Day, Another Exoplanet: NASA’s TESS Keeps Counting More. By Dennis Overbye, The New York Times. [https://www.nytimes.com/2019/01/07/science/exoplanets-tess-nasa.html] Excerpt: NASA’s new planet-hunting machine, the Transiting Exoplanet Survey Satellite, or TESS, is racking up scores of alien worlds. Less than a quarter of the way through a two-year search for nearby Earthlike worlds, TESS has already discovered 203 possible planets, according to George R. Ricker, an astrophysicist at the Massachusetts Institute of Technology, and the leader of the project. Three of those candidates already have been confirmed as real planets by ground-based telescopes. …All of these worlds would be located within 300 light years from here, our cosmic backyard, and close enough to be inspected by future telescopes, such as NASA’s ever-upcoming James Webb Space Telescope, for signs of atmospheres, habitability and, perhaps, life. …In the last three decades, and aided by NASA’s planet-hunting Kepler spacecraft, astronomers have concluded that there are billions of planets, including potentially habitable rocky worlds like Earth, in the Milky Way galaxy. The closest one, astronomers calculate, could be just 10 or 15 light years from here…. See also:

2019-01-07. ‘Mini-Neptune’ found orbiting distant star, by Sid Perkins. [https://www.sciencemag.org/news/2019/01/mini-neptune-found-orbiting-distant-star]

2018-11-14. Super-Earth spied in the second-closest star system from the sun. By Daniel Clery, Science Magazine. [https://www.sciencemag.org/news/2018/11/super-earth-spied-second-closest-star-system-sun] Excerpt: Our corner of the Milky Way is getting rather neighborly. In 2016, astronomers discovered a planet orbiting Proxima Centauri, the nearest star to our sun, just 4 light-years away. Now, they believe they have found an exoplanet around Barnard’s star, which at 6 light-years away is the second-closest star system. The planet—a chilly world more than three times heavier than Earth—is close enough that scientists could learn about its atmosphere with future giant telescopes. “This is going to be one of the best candidates,” says astronomer Nikku Madhusudhan of the University of Cambridge in the United Kingdom, who was not part of the discovery team. Barnard’s star b, as the new planet is called, was excruciatingly difficult to pin down, and the team is referring to it as a “candidate planet” though it is confident it’s there. …Hundreds of exoplanets have been found by looking for periodic Doppler shifts in the frequency of starlight. In 2015, astronomers saw hints of such shifts in the light from Barnard’s star. “Then we went hard for it,” says astronomer Ignasi Ribas of the Institute of Space Sciences in Barcelona, Spain, who led the new project. His team made observations from two ground-based telescopes in Chile and Spain …a spectrograph at Spain’s Calar Alto Observatory …archival data spanning 20 years from those and four other instruments, …a total of nearly 800 measurements. …they found that the star’s light oscillated every 233 days, implying a planet orbiting with a 223-day year….   

2018-10-30. NASA Retires Kepler Space Telescope, Passes Planet-Hunting Torch. NASA RELEASE 18-092. [https://www.nasa.gov/press-release/nasa-retires-kepler-space-telescope-passes-planet-hunting-torch] Excerpt: After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets – more planets even than stars – NASA’s Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life. “As NASA’s first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington. …The most recent analysis of Kepler’s discoveries concludes that 20 to 50 percent of the stars visible in the night sky are likely to have small, possibly rocky, planets similar in size to Earth, and located within the habitable zone of their parent stars. …most common size of planet Kepler found doesn’t exist in our solar system – a world between the size of Earth and Neptune – and we have much to learn about these planets.  …Four years into the mission, after the primary mission objectives had been met, mechanical failures temporarily halted observations. The mission team was able to devise a fix, switching the spacecraft’s field of view roughly every three months. This enabled an extended mission for the spacecraft, dubbed K2, which lasted as long as the first mission and bumped Kepler’s count of surveyed stars up to more than 500,000. …”We know the spacecraft’s retirement isn’t the end of Kepler’s discoveries,” said Jessie Dotson, Kepler’s project scientist at NASA’s Ames Research Center in California’s Silicon Valley. “I’m excited about the diverse discoveries that are yet to come from our data and how future missions will build upon Kepler’s results.”… See also New York Times Kepler, the Little NASA Spacecraft That Could, No Longer Can, Kepler Telescope Dead After Finding Thousands of Worlds, and Science Magazine article Kepler, NASA’s planet-hunting space telescope, is dead . Nov 16 -NASA Exoplanet News: Kepler Space Telescope Bid ‘Goodnight’ With Final Set of Commands.

2018-10-03. First moon outside the solar system could be as big as Neptune. By Joshua Sokol, Science Magazine. [https://www.sciencemag.org/news/2018/10/first-moon-outside-solar-system-could-be-big-neptune] Excerpt: With help from the Hubble Space Telescope, astronomers say they have found compelling evidence for the first known moon outside the solar system. …this first reported “exomoon” is also strange: a Neptune-size megamoon, some 8000 light-years away, that looms over a giant planet, twice as large in the sky as Earth’s moon. …Most theoretical models of planet formation struggle to produce such a hefty satellite. However, searches are biased toward the largest moons that might be out there, because bigger things are easier to detect. …The first hints for the exomoon came from archival data from the Kepler probe, a NASA planet-hunting spacecraft, which looks for dips in brightness caused by unseen planets transiting in front of their suns. Alex Teachey and David Kipping, both of Columbia University, found that three dips, attributed to the planet Kepler-1625b, might actually be caused by a planet and a moon. …They hoped Hubble, trained on another transit in October 2017, would clinch the case. …the team stands by its decision to publish its qualified probably-maybe discovery. “Science can’t operate by teams such as ourselves refusing to publish our results and hiding behind closed doors,” Kipping says in an online outreach video posted concurrently with the paper. “If refuted, then we have lost nothing, and the search goes on.”… See also NASA Release, Scientific American article Astronomers Tiptoe Closer to Confirming First Exomoon, and AGU/Eos article (with artist renderings by Dan Durda), Large Exomoon Likely Orbits a Faraway World.

2018-09-24. How Well Can the Webb Telescope Detect Signs of Exoplanet Life? By Lucas Joel, Eos/AGU. [https://eos.org/articles/how-well-can-the-webb-telescope-detect-signs-of-exoplanet-life] Excerpt: …what NASA’s next-generation, space-based telescope will be able to do: “see the first light of the universe, watch galaxies collide, see stars and planets being born, find and study exoplanets.” …recent research suggests that the [James Webb Space Telescope (JWST)] might have a tricky time detecting at least one telltale sign of life: oxygen in an exoplanet’s atmosphere. … Noah Planavsky, a biogeochemist at Yale University, and a team of researchers recently found that a planet’s atmosphere with an extremely small amount of oxygen can still support life. This finding means there could be planets that have only minute oxygen levels—but that nonetheless harbor life—that would appear to be dead to JWST. …JWST was not originally designed to scan distant planets for their oxygen concentrations. …JWST’s oxygen-spotting prospects may be dim, but Joshua Krissansen-Totton, an astrobiologist at the University of Washington, thinks there is a good chance that the telescope will be able to detect two other molecules that would suggest the presence of life: carbon dioxide and methane. It will be possible to spot those molecules in a planet’s atmosphere, Krissansen-Totton explained, because they emit light in the infrared portion of the spectrum….

2018-09-20. NASA’s TESS Starts Collecting Planets. By Dennis Overbye, The New York Times. [https://www.nytimes.com/2018/09/20/science/nasa-tess-planets.html] Excerpt: The satellite, launched in April, has already identified at least 73 stars that may harbor exoplanets, most of them new to astronomers. …They all need to be confirmed by other astronomers….

2018-08-01. The Kepler Revolution. By Kimberly M. S. Cartier, Eos/AGU. Excerpt: The Kepler Space Telescope will soon run out of fuel and end its mission. Here are nine fundamental discoveries about planets aided by Kepler in the 9 years since its launch. …Kepler Space Telescope, a small spacecraft that opened a large window to the many thousands of exoplanets strewn throughout the Milky Way …was exhibiting the first signs of low fuel and … would be functional for only a few more months. Its fuel tank hit critically low levels on 2 July, and mission scientists put Kepler into a no-fuel hibernation mode until its latest round of data can be downloaded on 2 August. …1. Planets Are Everywhere, Equally. …Through its unblinking gaze, Kepler discovered 4,571 planetary signatures, 2,327 of which have been confirmed as actual exoplanets. …2. The Solar System May Not Be Unique. …With the help of an artificial intelligence algorithm, Kepler discovered another star with the same number of planets as our solar system. The star, Kepler-90, is 2,545 light-years away and slightly hotter than the Sun. Seven of its eight planets were discovered in 2013, and the elusive eighth planet rounded out the set in December 2017. The data show that the orbits of all eight Kepler-90 exoplanets fit within Earth’s orbit around the Sun. …3. Earth May Not Be Unique. …So far, astronomers have confirmed 29 exoplanets less than twice the diameter of Earth that fall in or near their star’s habitable zone, a region of space surrounding a star that has the right temperature to keep water in a liquid state on the surface of a planet. Seventy more possible Earth cousins remain as candidate exoplanets until astronomers can verify them. …4. An Earth-Sized Planet May Not Be Earth-Like. …Worlds likely to be covered with molten lava abound in the Kepler data set. …Kepler found plenty of ocean worlds, too. …Kepler-22b, discovered in 2011, was the first example. …7. Planets Exist in Unlikely Places. …Kepler found that exoplanets can orbit two, three, or even four stars with relative ease. …8. Planets Follow Defined Trends and Come in Distinct Groups. …planets smaller than Neptune fall into two distinct and separate categories, like two branches of a family tree. The branches were already familiar to astronomers—rocky super-Earths and gaseous mini-Neptunes—but astronomers now know that the categories represent a more fundamental planet property. …9. Planets and Stars Can Be Oddballs…. https://eos.org/features/the-kepler-revolutionSee also 2018-10-17 Science Magazine article NASA’s planet-hunting space telescope nears its end.

2018-03-28. NASA’s new satellite brings the search for Earthlike exoplanets closer to home. By Daniel CleryMar, Science. Excerpt: Thanks to NASA’s pioneering Kepler probe, we know our galaxy is teeming with exoplanets …more than 2600 confirmed exoplanets, implying hundreds of billions in the Milky Way. The new efforts ..target Earth-size planets whose composition, atmosphere, and climate—factors in whether they might be hospitable to life—could be studied. Leading the charge is the Transiting Exoplanet Survey Satellite (TESS), a NASA mission due for launch on 16 April. The brainchild of researchers at the Massachusetts Institute of Technology (MIT) in Cambridge, the $337 million TESS project aims to identify at least 50 rocky exoplanets—Earth-size or bigger—close enough for their atmospheres to be scrutinized by the much larger James Webb Space Telescope (JWST), due for launch in 2020. …Like Kepler, TESS finds planets by staring at stars and looking for a dip in brightness as a planet passes in front, blocking some of the star’s light in a so-called transit. But whereas Kepler kept a fixed view, watching just 0.25% of the sky out to a distance of 3000 lightyears, TESS will maneuver to observe 85% of it, out to about 300 light-years. The spacecraft carries four telescopes that together will survey a strip of sky extending from the solar system’s pole to its equator, known as the ecliptic. The scopes will watch a strip for 27 days, then shift sideways and repeat the process. After observing 13 such strips over a year, covering almost an entire hemisphere of sky, TESS will flip over and survey the other hemisphere…. http://www.sciencemag.org/news/2018/03/nasa-s-new-satellite-brings-search-earthlike-exoplanets-closer-home

2018-03-26. Meet TESS, Seeker of Alien Worlds. By Dennis Overbye, The New York Times. Excerpt: …No earlier than 6:32 p.m. on April 16, …a little spacecraft known as the Transiting Exoplanet Survey Satellite, or TESS, bristling with cameras and ambition, will ascend on a SpaceX Falcon 9 rocket in a blaze of smoke and fire and take up a lengthy residence between the moon and the Earth. There it will spend the next two years, at least, scanning the sky for alien worlds. TESS is the latest effort to try to answer questions that have intrigued humans for millenniums and dominated astronomy for the last three decades: Are we alone? Are there other Earths? Evidence of even a single microbe anywhere else in the galaxy would rock science. …“Most of the stars with planets are far away,” said Sara Seager, a planetary scientist at the Massachusetts Institute of Technology and a member of the TESS team, referring to Kepler’s bounty. “TESS will fill in planets around nearby stars.” …Most of the exoplanets will be orbiting stars called red dwarfs, much smaller and cooler than the sun. They make up the vast majority of stars in our neighborhood (and in the universe) and presumably lay claim to most of the planets. Like Kepler, TESS will hunt those planets by monitoring the light from stars and detecting slight dips, momentary fading indicating that a planet has passed in front of its star…. https://www.nytimes.com/2018/03/26/science/tess-nasa-exoplanets.html

2018-01-24. Looking to the Future of Exoplanet Science. By Kimberly M. S. Cartier, Eos/AGU. Excerpt: Upcoming missions seeking to unravel the secrets of exoplanets abound. An informal survey of astronomers revealed which of those projects they most eagerly await. …Wide Field Infrared Survey Telescope (WFIRST)… expected launch is around 7 years …is not a dedicated exoplanet telescope. …WFIRST will be an imaging-only telescope hosting two instruments, a wide-field camera and a coronagraph,…. European Space Agency’s (ESA) upcoming planet hunter, called Planetary Transits and Oscillations of Stars (PLATO), … 6-year mission is not scheduled to launch until 2024, its goal of monitoring more than 1 million stars for signals of planetary transits…. NASA’s Transiting Exoplanet Survey Satellite (TESS) …is currently scheduled to lift off from Cape Canaveral Air Force Station in Florida this year, sometime from early March to late June. …TESS will conduct the first space-based, all-sky transit survey, which it will carry out in a mere 2 years. …TESS will monitor the brightest 200,000 stars in small patches of the sky for 27 days apiece before moving on to another area…. James Webb Space Telescope (JWST)…the successor to the HST, …is currently scheduled to launch from French Guiana in spring 2019. …JWST is not dedicated solely to the search for and characterization of exoplanets. After the telescope opens its “eyes,” it will observe planets, stars, galaxies, and the universe in equal proportion. Moreover, the planetary component of JWST’s mission is not even exclusive to exoplanets, as it will also explore planets and other objects in our solar system and study the potential for life close to home…. https://eos.org/articles/looking-to-the-future-of-exoplanet-science

2017-12-14. Artificial Intelligence, NASA Data Used to Discover Eighth Planet Circling Distant Star. By NASA RELEASE 17-098. Excerpt: Our solar system now is tied for most number of planets around a single star, with the recent discovery of an eighth planet circling Kepler-90, a Sun-like star 2,545 light-years from Earth. The planet was discovered in data from NASA’s Kepler Space Telescope. The newly-discovered Kepler-90i – a sizzling hot, rocky planet that orbits its star once every 14.4 days – was found using machine learning from Google. Machine learning is an approach to artificial intelligence in which computers “learn.” In this case, computers learned to identify planets by finding in Kepler data instances where the telescope recorded signals from planets beyond our solar system, known as exoplanets. “Just as we expected, there are exciting discoveries lurking in our archived Kepler data, waiting for the right tool or technology to unearth them,” said Paul Hertz, director of NASA’s Astrophysics Division in Washington. “This finding shows that our data will be a treasure trove available to innovative researchers for years to come.” The discovery came about after researchers Christopher Shallue and Andrew Vanderburg trained a computer to learn how to identify exoplanets in the light readings recorded by Kepler – the minuscule change in brightness captured when a planet passed in front of, or transited, a star. Inspired by the way neurons connect in the human brain, this artificial “neural network” sifted through Kepler data and found weak transit signals from a previously-missed eighth planet orbiting Kepler-90, in the constellation Draco. …“The Kepler-90 star system is like a mini version of our solar system. You have small planets inside and big planets outside, but everything is scrunched in much closer,” said Vanderburg, a NASA Sagan Postdoctoral Fellow and astronomer at the University of Texas at Austin. Shallue, a senior software engineer with Google’s research team Google AI, came up with the idea to apply a neural network to Kepler data. He became interested in exoplanet discovery after learning that astronomy, like other branches of science, is rapidly being inundated with data as the technology for data collection from space advances. “In my spare time, I started googling for ‘finding exoplanets with large data sets’ and found out about the Kepler mission and the huge data set available,” said Shallue. “Machine learning really shines in situations where there is so much data that humans can’t search it for themselves.” Kepler’s four-year dataset consists of 35,000 possible planetary signals. …Shallue and Vanderburg thought there could be more interesting exoplanet discoveries faintly lurking in the data. First, they trained the neural network to identify transiting exoplanets using a set of 15,000 previously-vetted signals from the Kepler exoplanet catalogue. In the test set, the neural network correctly identified true planets and false positives 96 percent of the time. Then, with the neural network having “learned” to detect the pattern of a transiting exoplanet, the researchers directed their model to search for weaker signals in 670 star systems that already had multiple known planets. …“We got lots of false positives of planets, but also potentially more real planets,” said Vanderburg. “It’s like sifting through rocks to find jewels….” Kepler-90i wasn’t the only jewel this neural network sifted out. In the Kepler-80 system, they found a sixth planet…. Earth-sized Kepler-80g, and four of its neighboring planets form what is called a resonant chain – where planets are locked by their mutual gravity in a rhythmic orbital dance. …Their research paper reporting these findings has been accepted for publication in The Astronomical Journal [https://www.cfa.harvard.edu/~avanderb/kepler90i.pdf]…. https://www.nasa.gov/press-release/artificial-intelligence-nasa-data-used-to-discover-eighth-planet-circling-distant-star [includes video]

2017-11-15. Nearby Earth-sized world may be the best candidate yet in the search for alien life. By Loren Grush, The Verge. Excerpt: …Meet Ross 128 b, a newly discovered planet found orbiting around a small, faint star known as a red dwarf. The world, which is about one-and-a-half times the mass of Earth, may be in the star’s habitable zone, too. (That’s the spot where temperatures are just right, possibly allowing liquid water to pool on a planet’s surface.) Most exciting of all is that this planet is situated just 11 light-years away. That makes Ross 128 b the second closest potentially habitable exoplanet to Earth we know about after Proxima b, a rocky world that orbits around the nearest star to our Solar System, Proxima Centauri. However, Proxima Centauri isn’t a very “life-friendly” star. Also a red dwarf, …it frequently burps out intense, high-energy solar flares. …But Ross 128 b’s star doesn’t seem to flare much at all. …Ross 128 b is very close to its sun, in an orbit that takes just 10 Earth days to complete. That puts the planet about 20 times closer to its star than Earth is to the Sun. But this star is also 280 times less luminous than our Sun, so Ross 128 b only receives about 40 percent more light than Earth does. That means the planet may have a surface temperature similar to Earth. …a new giant telescope is being built in Chile — aptly named the Extremely Large Telescope, or ELT — which could use to peer into this planet’s atmosphere. …the ELT may be powerful enough to directly image Earth-sized exoplanets and figure out what their atmospheres are made of… and find the critical gases associated with life — water vapor, oxygen, and methane — then scientists will have a better idea of whether life is present…. https://www.theverge.com/2017/11/15/16655236/new-planet-discovery-ross-128-b-red-dwarf

2017-06-22. Ten Earth-Sized Planets Found by Exoplanet-Hunting Telescope. By JoAnna Wendel, Earth & Space Science News, EoS, AGU. Excerpt: NASA introduced 219 exoplanet candidates to the world on Monday. Ten of these are roughly Earth sized and orbit their stars in the so-called habitable zone, a distance at which temperatures could be ripe for liquid water. The candidate exoplanets appear in the eighth and newest catalog from the agency’s exoplanet-hunting Kepler space telescope and the final catalog from Kepler’s observations of the Cygnus constellation. The new catalog includes 4034 exoplanet candidates overall. Past “Kepler catalogs have shown us that small exoplanets are common,” Susan Thompson, lead author on the catalog study and a research scientist at the SETI Institute in Mountain View, Calif., told Eos. “With this [latest] catalog, we can show whether this is also true for exoplanets that are in orbital periods similar to those of the Earth.” Accompanying research also reveals that the majority of known exoplanets fall into two distinct sizes: rocky exoplanets up to 1.75 times the radius of Earth and Neptune-sized gassy exoplanets. The finding, soon to be published in The Astronomical Journal, deepens scientists’ understanding of exoplanet diversity. …The team found that smaller exoplanets fall into two distinct size categories: rocky planets up to 1.75 times the radius of Earth and gassy planets 2–3.5 times the radius of Earth (or a touch shy of Neptune’s size). …The researchers speculate that these two categories could stem from the bodies’ hydrogen and helium compositions when they first formed. Just enough gas, and the planet could balloon in size and “jump the gap” to become a mini-Neptune, said Andrew Howard, an astronomer at Caltech and principal investigator on the new research. But a small amount of gas would get blown away by radiation from the planet’s host star….  https://eos.org/articles/ten-earth-sized-planets-found-by-exoplanet-hunting-telescope

2017-06-19. Earth-Size Planets Among Final Tally of NASA’s Kepler Telescope. By Dennis Overbye, The New York Times. Excerpt: …astronomers released a list on Monday of 4,034 objects they are 90 percent sure are planets orbiting other stars. The new list is the final and most reliable result of a four-year cosmic census of a tiny region of the Milky Way by NASA’s Kepler spacecraft. … The catalog — the eighth in the endeavor — was released at a meeting of exoplanet astronomers here at the Ames Research Center that represents a last hurrah for the survey mission, which will end on Sept. 30. The space telescope itself is doing fine, and it has embarked on a new program of short-term searches called K2. Among other things, Dr. Batalha said, for the first time there is at least one planet, known as KOI 7711 (for Kepler Object of Interest), that almost matches the Earth, at only 30 percent wider and with an orbit of almost exactly one year. In all, there are 219 new planet candidates in the catalog. Ten of them, moreover, are in the habitable zones of their stars, the so-called Goldilocks realm, where the heat from their stars is neither too cold nor too hot for liquid water. …A new study, led by Benjamin Fulton of the California Institute of Technology, of 1,305 stars and 2,025 planets that orbit them has found a curious gap in the planet population that seems to mark the boundary between rocky planets, which can be up to one and a half times the size of the Earth, (sometimes called super-Earths) and gaseous planets, so-called mini-Neptunes, which are more than about twice the size of Earth. (Neptune itself is four times the diameter and 17 times the mass of Earth.) …All planets seem to start out with about the same amount of rock in their cores, he said. How much gas — mostly hydrogen and helium from the primordial cloud that birthed us — adheres to them makes all the difference. While the Earth, which has hardly any atmosphere at all by weight, is a pleasant place, the pressure on a world with just a little more gas would be toxic. …Presumably, Mr. Fulton said, the planets that are rocky now, like Earth, had their gassy envelopes stripped away or evaporated by radiation from their stars. But nobody really knows how it works. Adding to the mystery is that our own solar system has no example of a mini-Neptune, and yet they are prevalent in alien planet systems….  https://www.nytimes.com/2017/06/19/science/kepler-planets-earth-like-census.html

2017-05-10. The Harmony That Keeps Trappist-1’s 7 Earth-size Worlds From Colliding. By Kenneth Chang, The New York Times. Excerpt: In February, astronomers announced the discovery of a nearby star with seven Earth-size planets, and at least some of the planets seemed to be in a zone that could provide cozy conditions for life. The finding of these planets circling the star Trappist-1 40 light-years away came with a bit of mystery. The orbits of the planets are packed tightly, and computer calculations by the discoverers suggested that the gravitational jostling would send the planets colliding with each other or flying apart, some to deep space, others spiraling into the star and destruction. Now new research provides an explanation for the dynamics of how this planetary system could have formed and remained in stable harmony over billions of years. …The scientist in the office next door to Dr. Tamayo …Matt Russo, an astrophysicist who is also a musician, turned to Dr. Tamayo’s computer simulations for help turning the orbits into notes, and they have produced a sort of music of the spheres for the 21st century. …Since the Trappist-1 planets are so close to their star, they orbit quickly, and their “year” — the time to complete one orbit — ranges from 1.5 days to 19 days. The original discoverers noted that those orbits were almost exactly in what scientists call “resonance.” …In more than 300 computer runs, each simulating five million years, the vast majority stayed stable, Dr. Tamayo said….  https://www.nytimes.com/2017/05/10/science/trappist-earth-size-planets-orbits-music.html  See also Youtube video https://www.youtube.com/watch?v=WS5UxLHbUKc – TRAPPIST Sounds: TRAPPIST-1 Planetary System Translated Directly Into Music.

2017 March. Whole New Worlds: An Aladdin History of Exoplanets—Video by A Capella Science, Trudbol, SamRobson, Gia Mora, (https://www.youtube.com/watch?v=gai8dMA19Sw).  8.5 min long.

2017-02-22. NASA telescope reveals largest batch of Earth-size, habitable-zone planets around single star. NASA RELEASE 17-015.  xcerpt:  NASA announced the discovery of the most Earth-sized planets found in the habitable zone of a single star, called TRAPPIST-1. This system of seven rocky worlds–all of them with the potential for water on their surface–is an exciting discovery in the search for life on other worlds. There is the possibility that future study of this unique planetary system could reveal conditions suitable for life…. https://www.nasa.gov/press-release/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around; See also NASA full press conference on discovery of 7 Earth-like exoplanets (37 min), TRAPPIST-1e Travel Poster, NY Times article – 7 Earth-Size Planets Orbit Dwarf Star, NASA and European Astronomers Say (includes video clip), JPL video – NASA & TRAPPIST-1: A Treasure Trove of Planets Found. 

2016-08-07. Martians Might Be Real. That makes Mars exploration way more complicated. By Kevin Carey, WIRED. Excerpt: History will note that the guy who discovered liquid water on Mars was an undergraduate at the University of Arizona, a 20-year-old who played guitar in a death-metal band and worked in a planetary science lab. …he noticed something odd: a set of dark streaks in the soil that grew in the Martian summer and shrank in the winter. They seemed to flow down the crater’s slope, like a spill. …in September of 2015, [NASA] called a big press conference. It confirmed … That was water in that crater. …About a month after the press conference, a NASA administrator named Cassie Conley was sitting in her office, staring into her computer screen at a crudely designed website called UFO Sightings Daily. …The item that Conley had come looking for was a photograph taken by the Curiosity rover and annotated by the website’s author. …that streak in the soil descending from a crook between two rocks? The guy had labeled it “water.” And it really did look like water. …It’s looking more and more likely that Mars might already be inhabited—by Martians. Very tiny ones. …Conley’s full-time job at NASA is to make sure that we don’t royally screw up our first encounter with aliens, however small. Her official title is US planetary protection officer. She’s a kind of interplanetary sheriff, whose main duty is to police the comings and goings of the tiniest Earthlings: microorganisms, which as it turns out are extraordinarily good at hitching rides on spacecraft.  …Conley’s office serves to prevent NASA from doing to Martians what European explorers did to Native Americans with smallpox.  …And the third main rationale for Conley’s office is, well, mildly apocalyptic…guarding this planet against potentially virulent alien life. …when Conley picked up the phone after her visit to UFO Sightings Daily, it wasn’t to spur Curiosity’s team on toward that possible water. It was to keep the rover away from it. …Because it’s impossible to eliminate all of the microbes from a Mars rover, even the most stringent decontamination protocols are defined in ratios and probabilities. The most Conley can do is make sure there are no more than 0.03 microbes per square meter of spacecraft surface area. That was the standard applied to the Viking mission in 1976.  …Conley’s job is, by nature, a pretty lonely one. She’s a microbiologist in an agency dominated by physicists and engineers, a woman in a field dominated by men, and a sheriff (someone even gave her a joke badge) who stands a head shorter than many of her colleagues.  …The curiosity rover wasn’t supposed to be high on Conley’s list of worries. NASA had deliberately sent it to Gale Crater, thought to be among the least likely places to harbor life, because the rover was largely built for geological research. She’d helped pick the landing site herself. When Curiosity left Earth in 2011, it was subjected to milder decontamination controls: It was allowed 300 organisms per square meter. Now, trundling around a possibly somewhat damp Gale Crater millions of miles away, Curiosity was very likely infested with tens of thousands of hardy Earth microbes that had survived the violent blastoff and months-long journey through the harsh vacuum of space. All they needed to reanimate and reproduce was the right combination of food, water, and heat. …Mars 2020, which will land another robot rover much like Curiosity … will be designed to search for signs of ancient microbial life on Mars and—even more ambitiously—to collect soil samples that can be retrieved by another spacecraft and sent back to Earth. …observers inside and outside of NASA say they’re in a heated battle with the Office of Planetary Protection over where they can land and what measures they need to take to sterilize their craft before it leaves for Mars….  http://www.wired.com/2016/08/shouldnt-go-mars-might-decimate-martians

2016-07-20. NASA’s Hubble Telescope Makes First Atmospheric Study of Earth-Sized Exoplanets.NASA RELEASE 16-076. Excerpt: Using NASA’s Hubble Space Telescope, astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system and found indications that increase the chances of habitability on two exoplanets. …the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds. …The planets orbit a red dwarf star at least 500 million years old, in the constellation of Aquarius. They were discovered in late 2015 through a series of observations by the TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST), a Belgian robotic telescope located at ESA’s (European Space Agency’s) La Silla Observatory in Chile. TRAPPIST-1b completes a circuit around its red dwarf star in 1.5 days and TRAPPIST-1c in 2.4 days. The planets are between 20 and 100 times closer to their star than the Earth is to the sun. Because their star is so much fainter than our sun, researchers think that at least one of the planets, TRAPPIST-1c, may be within the star’s habitable zone, where moderate temperatures could allow for liquid water to pool. On May 4, astronomers took advantage of a rare simultaneous transit, when both planets crossed the face of their star within minutes of each other, to measure starlight as it filtered through any existing atmosphere. This double-transit, which occurs only every two years, provided a combined signal that offered simultaneous indicators of the atmospheric characters of the planets. …Observations from future telescopes, including NASA’s James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet’s temperature and surface pressure – key factors in assessing its habitability. …The results of the study appear in the July 20 issue of the journal Nature….  http://www.nasa.gov/press-release/nasa-s-hubble-telescope-makes-first-atmospheric-study-of-earth-sized-exoplanets

2016-05-16. Aging Stars Make New Habitable Zones. By JoAnna Wendel, EoS-Earth & Space Science News (AGU).  Excerpt: Scientists searching for life in the universe now have a new target: the once-icy worlds orbiting red giants. There’s some good news and bad news for Europa colonization enthusiasts. As our Sun gets older, brighter, and bigger over the next several billion years, it will expand into a red giant so large that its heat could melt ice on the surface of Europa and other moons of Jupiter, as well as those around Saturn. Liquid water flowing freely would not only be a boon for would-be space explorers, but it could provide a stable environment ripe for fostering life. The bad news is Earth will be burnt to a crisp. It may even get engulfed by the fiery wall of the expanding star, along with Mercury and Venus, so anyone that remains on Earth probably won’t live to see that day. For right now, however, humans who study planets orbiting other stars stand to benefit from the grim future prospects of our solar system’s innermost planets. A new model of the evolution of stellar systems’ habitable zones, based on what’s expected for our own solar system, could help observers today better evaluate which exoplanets could harbor life….  https://eos.org/articles/aging-stars-make-new-habitable-zones

2016-02-18. Berkeley Lab, UC Berkeley Scientists to Participate in New NASA Space Telescope Project. By Glen Roberts Jr., Berkeley Lab News Center. Excerpt: WFIRST will explore mysteries of dark energy, hunt for distant planets, retrace universe’s history during 6-year mission. …The Wide Field Infrared Survey Telescope (WFIRST) will launch into its six-year mission from Cape Canaveral, Fla., in the mid-2020s. …The telescope will be NASA’s next major astrophysics observatory following the launch of the James Webb Space Telescope in 2018. …WFIRST is a 2.4-meter telescope with a primary mirror the same size as that of the Hubble Space Telescope. It has a field of view that is 100 times larger than Hubble’s infrared instrument and will measure light from an estimated billion galaxies. WFIRST is a 2.4-meter telescope with a primary mirror the same size as that of the Hubble Space Telescope. It has a field of view that is 100 times larger than Hubble’s infrared instrument and will measure light from an estimated billion galaxies….  http://newscenter.lbl.gov/2016/02/18/berkeley-lab-role-wfirst/

2015-01-06. So Many Earth-Like Planets, So Few Telescopes. By Dennis Overbye, The New York Times. Front page story. Excerpts: Astronomers announced on Tuesday that they had found eight new planets orbiting their stars at distances compatible with liquid water, bringing the total number of potentially habitable planets in the just-right “Goldilocks” zone to a dozen or two, depending on how the habitable zone of a star is defined. NASA’s Kepler spacecraft, now in its fifth year of seeking out the shadows of planets circling other stars, has spotted hundreds, and more and more of these other worlds look a lot like Earth — rocky balls only slightly larger than our own home, that with the right doses of starlight and water could turn out to be veritable gardens of microbial Eden. …Reviewing the history of exoplanets, Debra Fischer, a Yale astronomer, recalled that the first discovery of a planet orbiting another normal star, a Jupiter-like giant, was 20 years ago. Before that, she said, astronomers worried that “maybe the ‘Star Trek’ picture of the universe was not right, and there is no life anywhere else.” Dr. Fischer called the progress in the last two decades “incredibly moving.” And yet we still do not have a clue that we are not alone. “We can count as many as we like,” said Sara Seager, a planet theorist at the Massachusetts Institute of Technology who was not involved in the new work, “but until we can observe the atmospheres and assess their greenhouse gas power, we don’t really know what the surface temperatures are like.”  http://www.nytimes.com/2015/01/07/science/space/as-ranks-of-goldilocks-planets-grow-astronomers-consider-whats-next.html

2014-07-10. NASA Spacecraft Observes Further Evidence of Dry Ice Gullies on Mars. Excerpt: Repeated high-resolution observations made by NASA’s Mars Reconnaissance Orbiter (MRO; http://www.nasa.gov/mro ) indicate the gullies on Mars’ surface are primarily formed by the seasonal freezing of carbon dioxide, not liquid water. The first reports of formative gullies on Mars in 2000 generated excitement and headlines because they suggested the presence of liquid water on the Red Planet, …. Mars has water vapor and plenty of frozen water, but the presence of liquid water on the neighboring planet, a necessity for all known life, has not been confirmed. This latest report about gullies has been posted online by the journal Icarus. “As recently as five years ago, I thought the gullies on Mars indicated activity of liquid water,” said lead author Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Flagstaff, Arizona. “…we saw that the activity occurs in winter.” Dundas and collaborators used the High Resolution Imaging Science Experiment (HiRISE; http://hirise.lpl.arizona.edu ) camera on MRO to examine gullies at 356 sites on Mars, beginning in 2006. …Using dated before-and-after images, researchers determined the timing of this activity coincided with seasonal carbon dioxide frost and temperatures that would not have allowed for liquid water. …The findings in this latest report suggest all of the fresh-appearing gullies seen on Mars can be attributed to processes currently underway, whereas earlier hypotheses suggested they formed thousands to millions of years ago when climate conditions were possibly conducive to liquid water on Mars…. http://www.nasa.gov/press/2014/july/nasa-spacecraft-observes-further-evidence-of-dry-ice-gullies-on-mars/#.U_t1t0iprZF. NASA RELEASE 14-191.

2014-04-17. First Earth-Size Planet in ‘Habitable Zone’. Excerpt: Using NASA’s Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the “habitable zone” — the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun. While planets have previously been found in the habitable zone, they are all at least 40 percent larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth. “The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth,” said Paul Hertz, NASA’s Astrophysics Division director at the agency’s headquarters in Washington. “Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind’s quest to find truly Earth-like worlds.” http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=330. By NASA Kepler mission. See NASA RELEASE 14-111. See also: http://kepler.nasa.gov/news/keplerinthenews/index.cfm?FuseAction=ShowNews&NewsID=332.

2013-04-18. Kepler’s Smallest Habitable Zone Planets.    NASA    Kepler mission    …We’re a step closer to knowing if our galaxy is home to a multitude of planets like Earth or if we are a rarity. The three habitable zone super-Earth-size planets are in two systems containing a total of seven newly discovered planets…Star Kepler-62 is not Sun-like: just 2/3 the size of the Sun, cooler, older, and only 1/5 as bright. Planet Kepler-62f, 40% larger than Earth, the smallest known habitable zone exoplanet, orbits every 267 days. Planet Kepler-62e, about 60% larger than Earth, orbits every 122 days in the the habitable zone’s inner edge. http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=243

2009 October 19. Many More Planets Found Outside Solar System. NY Times. Excerpt: WASHINGTON(AP) — European astronomers have found 32 new planets outside our solar system, adding evidence to the theory that the universe has many places where life could develop. Scientists using the European Southern Observatory telescope didn’t find any planets quite the size of Earth or any that seemed habitable or even unusual. But their announcement increased the number of planets discovered outside the solar system to more than 400.
Six of the newly found planets are several times bigger than Earth, increasing the population of so-called super-Earths by more than 30 percent. Most planets discovered so far are far bigger, Jupiter-sized or even larger.
Two of the newly discovered planets were as small as five times the size of Earth and one was up to five times larger than Jupiter.
…What astronomers said is especially exciting is that about 40 percent of sun-like stars have planets that are closer to being Earth-sized than the size of Jupiter. Jupiter’s mass is more than 300 times that of Earth’s….

2009 Aug 31. A Doomed Planet, and Scientists Are Lucky to Have Spotted It. By Kenneth Chang. Excerpt: Were astronomers just lucky when they discovered the planet WASP-18b? …about 10 times the mass of Jupiter), close to the parent star (about 1.9 million miles away, or just one-fiftieth of the distance between the Sun and Earth) and hot (3,800 degrees Fahrenheit). About one-quarter of the nearly 400 planets discovered so far have been such “hot Jupiters. But as an international team of astronomers looked more closely, they became more surprised that they had seen WASP-18b at all. The tidal forces between a star and a planet dissipate energy, and WASP-18b is so close that it should fall into its host star in less than a million years – an eye blink on the cosmic scale….

2009 July 20. Searching for Extraterrestrial Life. By Claudia Dreifus, The NY Times. Excerpt: At his day job, Alan Boss of the Carnegie Institution of Washington studies how stars and planets are born. In recent years, he has consulted with scientists for NASA’s Kepler space telescope on their mission of finding planets outside our solar system that might be hospitable to life. Mr. Boss, a 58-year-old astronomer and theoretical astrophysicist, was in New York City recently to promote his new book, “The Crowded Universe: the Search for Living Planets,” about the scientific hunt for extraterrestrial life….
Q. ON MARCH 6, A DELTA 2 ROCKET CARRYING THE KEPLER SPACE TELESCOPE WAS LAUNCHED FROM CAPE CANAVERAL. WHAT DID YOU THINK AS YOU WATCHED THE LIFTOFF?
A. Now we’re ready to do some science! The big payoff is coming!
Kepler’s mission is to detect planets outside our solar system that roughly have the same size, conditions and distance from their stars as Earth. We think the probability of finding extraterrestrial life would be best on Earth-like planets. From previous observations, we know of about 330 “extra-solar” planets. Kepler is likely to send us evidence of hundreds of Earth-like planets revolving around hundreds of Sun-like stars.
Q. YOU ARE A BIG BELIEVER IN “WE ARE NOT ALONE.” WHY?
A. From ground-based observations, we know that Earth-like planets are going to be quite common. Estimates are that “earths” probably occur in 10 to 20 percent of the stars. My feeling is that if you have that many earths and you have some prebiotic soup, comets that bring in the organic chemicals that you need to have life, something is going to grow….

2009 June 17. Exoplanet Has Oddball Orbit. By Nancy Atkinson, Universe Today. Excerpt: In what might be a evidence of planetary billiards, astronomers have found an exoplanet with an extremely odd orbit. The question is, was this planet the cue ball or the object ball? While most planets orbit around a star’s mid-section, this one – called XO-3b — is tilted about 37 degrees from the star’s equator. It’s also a massive planet, about 10 times the size of Jupiter. Such a misalignment must have occurred as a result of a disturbance, such as a collision with another object, sometime after the planet’s formation. But astronomers say they don’t yet know what caused the unusual orbit of XO-3b.
…The planet was discovered back in 2007 using the transit method by measuring how the star is dimmed by the planet passing in through the line-of-sight between Earth and the star.
…But to go one step further and measure the angle of its orbit, meant that “we have to be sneaky about it,” said MIT physicist Joshua Winn, who led the team that measured the planet’s tilted orbit. It turns out that if a planet crosses the star’s disk at an angle to the star’s own rotation, it causes a distinctive pattern of change in the overall color of the star, as measured by a highly sensitive spectrograph, because of the Doppler shifts caused by the star’s rotation.
…Such “hot Jupiters” …could not have formed in the places they are seen now, according to accepted planet-formation theory. They must have formed much further out from the star, then migrated inward to their present positions. Astronomers have come up with different mechanisms to account for the migration: the gravitational attraction of other planets as they passed close by, or the attraction of the disk of dust and gas from which the star and its planets formed.
Close encounters with other planets could greatly amplify a slight initial tilt, but attraction from the disk of material could not. Likely, a cataclysmic event occurred in this planet’s past….

2009 April 21. Astronomers Find Planet Closer to Size of Earth. By Dennis Overbye, The NY Times. Excerpt: European astronomers said Tuesday that they had discovered the smallest planet yet found orbiting another star. The planet could be as little as only 1.9 times as massive as the Earth and belongs to a dim red star known as Gliese 581, which lies about 20 light-years from Earth in the constellation Libra.
The star was already know to harbor at least three more massive planets. The new planet, known as Gliese 581e, is probably rocky like the Earth, but it lies in such a close orbit — only three million miles from its star — that it is surely blasted with too much radiation and heat to be livable.
…Astronomers said the discovery was more encouragement that the galaxy was full of small-mass planets and that with more time and improved instruments like the Kepler satellite, recently launched by NASA, they would eventually find Earth-like planets in orbits suitable for life around other stars.
“Finding Earth-like planets with lukewarm temperatures is the next great goal,” Geoff Marcy, of the University of California, Berkeley, a planet-hunting rival of Dr. Mayor’s, said in an e-mail message….

2009 March 2. In a Lonely Cosmos, a Hunt for Worlds Like Ours. By Dennis Overbye, The NY Times. Excerpt: …Presently perched on a Delta 2 rocket at Cape Canaveral is a one-ton spacecraft called Kepler. If all goes well, the rocket will lift off about 10:50 Friday evening on a journey that will eventually propel Kepler into orbit around the Sun. There the spacecraft’s mission will be to discover Earth-like planets in Earth-like places — that is to say, in the not-too-cold, not-too-hot, Goldilocks zones around stars where liquid water can exist.
The job, in short, is to find places where life as we know it is possible.
“It’s not E.T., but it’s E.T.’s home,” said William Borucki, an astronomer at NASA’s Ames Research Center at Moffett Field in California, who is the lead scientist on the project. Kepler…will look for tiny variations in starlight caused by planets passing in front of their stars. Dr. Borucki and his colleagues say that Kepler could find dozens of such planets — if they exist. The point is not to find any particular planet — hold off on the covered-wagon spaceships — but to find out just how rare planets like Earth are in the cosmos.
…Kepler’s strategy is, in effect, to search for the shadows of planets. The core of the spacecraft, which carries a 55-inch-diameter telescope, is a 95-million-pixel digital camera. For three and a half years, the telescope will stare at the same patch of sky about 10 degrees, or 20 full moons, wide, in the constellations Cygnus and Lyra. It will read out the brightnesses of 100,000 stars every half-hour, looking for the telltale blips when a planet crosses in front of its star, a phenomenon known as a transit.
To detect something as small as the Earth, the measurements need to be done with a precision available only in space, away from the atmospheric turbulence that makes stars twinkle, and far from Earth so that our home world does not intrude on the view of shadow worlds in that patch of sky. It will take three or more years — until the end of Barack Obama’s current term in office — before astronomers know whether Kepler has found any distant Earths….

2008 November / December. The stars her destination. BY ROBERTA KWOK, California Alumni Magazine. A business major’s epiphany leads her to become a NASA scientist. Excerpt: Natalie Batalha’s worst enemy is the clock. Installed around the corner from her office at NASA Ames Research Center, a looming LED display is counting the days, hours, minutes and seconds until the launch of the Kepler Mission: NASA’s first attempt to find habitable Earth-like planets in our galaxy.
“It’s terrible,” says Batalha ’89, who has been working on the mission for eight years. “It recently rolled over from 300 to 299, and I could just feel my blood pressure rising.”
When the clock runs down to zero next spring, Batalha will stand with her family at Cape Canaveral in Florida to watch Kepler’s take-off. The spacecraft’s telescope will peer at one slice of the sky for three-and-a-half years, to look for signs of terrestrial planets using a technique called the transit method. Batalha likens the process to a fly passing in front of a car’s headlight: Every time a planet passes in front of the star it orbits, it dims the star’s light a little, the same way a fly would dim a headlight as it flew past. As part of preparation for launch, Batalha has been choosing-very, very carefully-the 170,000 stars that Kepler will observe from among the 13 million in its field of view.
Batalha may be feeling the pressure, but it doesn’t show. Her voice has the warm, calming quality of a public radio host, and when she demonstrates the orbit of a planet around a star, her movements are poised and exact. “Can you imagine that within your lifetime, you will probably be able to look up in the sky and say, ‘That star right there has a habitable Earth-like planet orbiting it’?” asks Batalha, an associate professor at San Jose State University. “That’s astounding. It’s going to change the way people understand their place in the universe.”….