The Mysteries of the Cosmos – a panel discussion with astronomers Phil Plait, Mike Brown, Debra Fischer, Andrea Ghez, and Saul Perlmutter. Topics: newly discovered solar system objects; the black hole in our galaxy; expansion of our universe.
2022-08-09. Webb telescope reveals unpredicted bounty of bright galaxies in early universe. [https://www.science.org/content/article/webb-telescope-reveals-unpredicted-bounty-bright-galaxies-early-universe] By Daniel Clery, Science Magazine. Excerpt: Star formation after the big bang appears much faster than models had forecast. The James Webb Space Telescope has only been watching the sky for a few weeks, and it has already delivered a startling finding: tens, hundreds, maybe even 1000 times more bright galaxies in the early universe than astronomers anticipated. “No one was expecting anything like this,” says Michael Boylan-Kolchin of the University of Texas, Austin. “Galaxies are exploding out of the woodwork,” says Rachel Somerville of the Flatiron Institute. Galaxy formation models may now need a revision, as current ones hold that gas clouds should be far slower to coalesce into stars and galaxies than is suggested by Webb’s galaxy-rich images of the early universe, less than 500 million years after the big bang. “This is way outside the box of what models were predicting,” says Garth Illingworth of the University of California (UC), Santa Cruz. …Within days after Webb began observations, it spotted a candidate galaxy that appears to have been shining brightly when the universe was just 230 million years old, 1.7% of its current age, which would make it the most distant ever seen. Surveys since then have shown that object is just one of a stunning profusion of early galaxies, each small by today’s standards, but more luminous than astronomers had expected.…
2022-05-12. Shadow of Milky Way’s giant black hole seen for the first time. By Daniel Clery, Science Magazine. Excerpt: After 5 years, astronomers release picture of Sagittarius A*’s event horizon, ringed by bright gas. Astronomers today released the first image of the supermassive black hole at the center of the Milky Way Galaxy—or at least a picture of its shadow. Eight radio observatories around the globe and more than 300 scientists joined forces to image the object known as Sagittarius A* (Sgr A*), a feat thought impossible until just a few years ago. …The team, known as the Event Horizon Telescope (EHT), in 2019 produced the first ever image of a black hole, at the center of the nearby giant galaxy M87. The M87 black hole is 1600 times more massive than Sgr A*. Yet the similarity of the two images—bright rings of gas trapped in death spirals around these ultimate sinkholes—shows how Albert Einstein’s theory of gravity, general relativity, works the same at all scales.… [https://www.washingtonpost.com/science/2022/05/11/black-hole-milky-way] See also Washington Post article Supermassive black hole seen at the center of our galaxy by Joel Achenbach, and Smithsonian Magazine article Here’s What the Black Hole in the Center of the Milky Way Looks Like.
2020-10-28. The universe teems with weird black holes, gravitational wave hunters find. By Adrian Cho, Science Magazine. Excerpt: Less than 5 years ago, physicists rocked the scientific world when they first spotted gravitational waves—fleeting ripples in space and time—set off when two gargantuan black holes billions of light-years away swirled into each other. Since then, scientists have detected a scad of similar events, mostly reported event by event. Today, however, researchers with a global network of gravitational wave detectors announced the first major statistical analyses of their data so far, 50 events in all. Posted online in four papers, the analyses show that black holes—ghostly ultraintense gravitational fields left behind when massive stars collapse—are both more common and stranger than expected. They also shed light on mysteries such as how such black holes pair up before merging…. [https://www.sciencemag.org/news/2020/10/universe-teems-weird-black-holes-gravitational-wave-hunters-find]
2020-08-12. Extremely young galaxy is Milky Way look-alike. By Science Daily. Excerpt: Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, have revealed an extremely distant and therefore very young galaxy that looks surprisingly like our Milky Way. The galaxy is so far away its light has taken more than 12 billion years to reach us: we see it as it was when the Universe was just 1.4 billion years old. It is also surprisingly unchaotic, contradicting theories that all galaxies in the early Universe were turbulent and unstable. This unexpected discovery challenges our understanding of how galaxies form, giving new insights into the past of our Universe. “This result represents a breakthrough in the field of galaxy formation, showing that the structures that we observe in nearby spiral galaxies and in our Milky Way were already in place 12 billion years ago,” says Francesca Rizzo, PhD student from the Max Planck Institute for Astrophysics in Germany, who led the research published today in Nature [https://www.nature.com/articles/s41586-020-2572-6]…. [https://www.sciencedaily.com/releases/2020/08/200812115304.htm]
2020-08-11. This is the way the universe ends: not with a whimper, but a bang. By Adam Mann, Science Magazine. Excerpt: In the unimaginably far future, cold stellar remnants known as black dwarfs will begin to explode in a spectacular series of supernovae, providing the final fireworks of all time. That’s the conclusion of a new study, which posits that the universe will experience one last hurrah before everything goes dark forever. …The known laws of physics suggest that by about 10100 (the No. 1 followed by 100 zeros) years from now, star birth will cease, galaxies will go dark, and even black holes will evaporate through a process known as Hawking radiation, leaving little more than simple subatomic particles and energy. The expansion of space will cool that energy nearly to 0 kelvin, or absolute zero, signaling the heat death of the universe and total entropy. …The particles in a white dwarf stay locked in a crystalline lattice that radiates heat for trillions of years, far longer than the current age of the universe. But eventually, these relics cool off and become a black dwarf. …over long time periods, quantum mechanics allows particles to tunnel through energetic barriers, meaning fusion can still occur, albeit at extremely low rates. When atoms such as silicon and nickel fuse toward iron, they produce positrons, the antiparticle of an electron. These positrons would ever-so-slowly destroy some of the electrons in a black dwarf’s center and weaken its degeneracy pressure. For stars between roughly 1.2 and 1.4 times the Sun’s mass—about 1% of all stars in the universe today—this weakening would eventually result in a catastrophic gravitational collapse that drives a colossal explosion similar to the supernovae of higher mass stars, Caplan reports this month in the Monthly Notices of the Royal Astronomical Society. Caplan says the dramatic detonations will begin to occur about 101100 years from now, a number the human brain can scarcely comprehend. The already unfathomable number 10100 is known as a googol, so 101100 would be a googol googol googol googol googol googol googol googol googol googol googol years. The explosions would continue until 1032000 years from now, which would require most of a magazine page to represent in a similar fashion…. [https://www.sciencemag.org/news/2020/08/way-universe-ends-not-whimper-bang]
2020-04-24. Hubble Marks 30 Years of Seeing a Universe Being Born and Dying. By Dennis Overbye, The New York Times. Excerpt: As shown in a new picture of stormy star birth in a nearby galaxy, captured by the Hubble Space Telescope, the cosmos is keeping up the tradition of both birth and death. Stars are being born out of the ashes of old ones, forever refreshing the universe. The picture was released Friday by the Space Telescope Science Institute in Baltimore, keepers of the Hubble, in honor of the 30th anniversary of the launch of that telescope on April 24, 1990…. [https://www.nytimes.com/2020/04/24/science/hubble-telescope-30th-birthday.html]
2020-03-06. This Black Hole Blew a Hole in the Cosmos. By Dennis Overbye, The New York Times. Excerpt: If there were ever sentient beings in the Ophiuchus cluster, a faraway conglomeration of galaxies in the southern sky, they are long gone. A few hundred million years ago, a mighty cosmic storm swept through that region of space. Hot gas suffuses the cluster, but the storm blew a crater through it more than a million light-years wide, leaving just a near-vacuum, a nattering haze of ultrahot electrical particles. The culprit, astronomers suspect, was a gigantic outburst of energy from a supermassive black hole — the biggest explosion ever documented in the universe, according to Simona Giacintucci, a radio astronomer at the Naval Research Laboratory and the leader of the research team…. [https://www.nytimes.com/2020/03/06/science/black-hole-cosmos-astrophysics.html]
2019-04-10. The first picture of a black hole opens a new era of astrophysics. By Lisa Grossman and Emily Conover, ScienceNews. [https://www.sciencenews.org/article/black-hole-first-picture-event-horizon-telescope] Excerpt: A world-spanning network of telescopes called the Event Horizon Telescope [EHT; https://eventhorizontelescope.org/] zoomed in on the supermassive monster in the galaxy M87 to create this first-ever picture of a black hole. …“We’ve been studying black holes so long, sometimes it’s easy to forget that none of us have actually seen one,” France Córdova, director of the National Science Foundation…. …The image also provides a new measurement of the black hole’s size and heft. …Estimates made using different techniques have ranged between 3.5 billion and 7.22 billion times the mass of the sun. But the new EHT measurements show that its mass is about 6.5 billion solar masses. …The team has also determined the behemoth’s size — its diameter stretches 38 billion kilometers — and that the black hole spins clockwise. “M87 is a monster even by supermassive black hole standards,” Markoff said. EHT trained its sights on both M87’s black hole and Sagittarius A*, the supermassive black hole at the center of the Milky Way. But, it turns out, it was easier to image M87’s monster. That black hole is 55 million light-years from Earth in the constellation Virgo, about 2,000 times as far as Sgr A*. But it’s also about 1,000 times as massive as the Milky Way’s giant, which weighs the equivalent of roughly 4 million suns…. See also Size Comparison: The M87 Black Hole and our Solar System [https://xkcd.com/2135/] and Science Magazine article [https://www.sciencemag.org/news/2019/04/black-hole]
2018-10-31. This ball of gas is racing around the black hole at our galaxy’s heart. By Daniel Clery, Science Magazine. [https://www.sciencemag.org/news/2018/10/ball-gas-racing-around-black-hole-our-galaxy-s-heart] Excerpt: Earlier this year, astronomers were looking for signs that S2, the star with the closest known orbit to the supermassive black hole thought to be at the center of the Milky Way, might—as predicted by Albert Einstein—deviate from the orbital path proscribed by Newtonian gravity. But while they were watching, they spied something else: three bright infrared flares unrelated to the star …the signs of superheated gas racing almost as close to the black hole as possible without getting sucked in—at 30% the speed of light. Observing the action so close to the galactic center, known as Sagittarius A*, is extremely challenging because it is distant, small, and shrouded in gas and dust. The team used the world’s largest optical instrument, the European Southern Observatory’s Very Large Telescope in Chile, and combined the light of its four 8.2-meter mirrors to get the resolution of a 130-meter virtual telescope using a new instrument called GRAVITY. …the three flares move in small 45-minute orbits, and …scientists calculated that this must be material circulating around the black hole, just outside the closest orbit in which objects can move without being sucked in….
2018-10-29. Move over, Hubble: Discovery of expanding cosmos assigned to little-known Belgian astronomer-priest. By Daniel Clery, Science Magazine. [https://www.sciencemag.org/news/2018/10/move-over-hubble-discovery-expanding-cosmos-assigned-little-known-belgian-astronomer] Excerpt: Hubble’s Law, a cornerstone of cosmology that describes the expanding universe, should now be called the Hubble-Lemaître Law, following a vote by the members of the International Astronomical Union (IAU), the same organization that revoked Pluto’s status as a planet. The change is designed to redress the historical neglect of Georges Lemaître, a Belgian astronomer and priest who in 1927 discovered the expanding universe—which also suggests a big bang. Lemaître published his ideas 2 years before U.S. astronomer Edwin Hubble described his observations that galaxies farther from the Milky Way recede faster. …In 1927 Lemaître calculated a solution to Albert Einstein’s general relativity equations that indicated the universe could not be static but was instead expanding. He backed up that claim with a limited set of previously published measurements of the distances of galaxies and their velocities, calculated from their Doppler shifts. …In 1929, Hubble published his own observations showing a linear relationship between velocity and distance for receding galaxies. …The text of the IAU resolution, circulated to members ahead of the vote, asserts that Hubble and Lemaître met in 1928, at an IAU general assembly in Leiden, the Netherlands…and “exchanged views” about the blockbuster theory. …Hubble never claimed to have discovered cosmic expansion, but did do much of observing work to nail down how fast the universe was expanding. “If the law is about the empirical relationship, it should be Hubble’s Law,” Kragh says. “If it is about cosmic expansion, it should be Lemaître’s Law.”…
2018-05-01. Gaia’s Map of 1.3 Billion Stars Makes for a Milky Way in a Bottle. By Dennis Overbye, The New York Times. Excerpt: …astronomers in Europe released a three-dimensional map of the Milky Way. It is the most detailed survey ever produced of our home galaxy. It contains the vital statistics of some 1.3 billion stars — about one percent of the entire cosmic panoply of which Earth and the sun are part. Not to mention measurements of almost half a million quasars, asteroids and other flecks in the night. Analyzing all these motions and distances, astronomers say, could provide clues to the nature of dark matter. The gravity of that mysterious substance is said to pervade space and sculpt the arrangements of visible matter. Gaia’s data could also reveal information about the history of other forces and influences on our neighborhood in the void. And it could lead to a more precise measurement of a historically troublesome parameter called the Hubble constant, which describes how fast the universe is expanding. The map is the latest result from the European Space Agency’s Gaia mission, which was launched into an orbit around the sun in December 2013. …Gaia’s cameras find the distances to stars by triangulation, measuring how their images shift against background stars and quasars as the spacecraft swings from one side of its orbit to the other — a baseline of about 186 million miles. A preliminary data release, containing information on 2 million stars, was published in 2016….https://www.nytimes.com/2018/05/01/science/gaia-map-milky-way.html
2017-10-16. LIGO Detects Fierce Collision of Neutron Stars for the First Time. By Dennis Overbye, The New York Times. Excerpt: Astronomers announced on Monday that they had seen and heard a pair of dead stars collide, giving them their first glimpse of the violent process by which most of the gold and silver in the universe was created. The collision, known as a kilonova, rattled the galaxy in which it happened 130 million light-years from here in the southern constellation of Hydra, and sent fireworks across the universe. On Aug. 17, the event set off sensors in space and on Earth, …. Such explosions, astronomers have long suspected, produced many of the heavier elements in the universe, including precious metals like gold, silver and uranium. …a pair of neutron stars, the shrunken dense cores of stars that have exploded and died, collided at nearly the speed of light. These stars are masses as great as the sun packed into a region the size of Manhattan brimming with magnetic and gravitational fields. …“It’s the greatest fireworks show in the universe,” said David Reitze of the California Institute of Technology and the executive director of the Laser Interferometer Gravitational-Wave Observatory, or LIGO. Daniel Holz, an astrophysicist at the University of Chicago and a member of the LIGO Scientific Collaboration, a larger group that studies gravitational waves, said, “I can’t think of a similar situation in the field of science in my lifetime, where a single event provides so many staggering insights about our universe.” The key to the discovery was the detection of gravitational waves, emanating like ripples in a pond vibrating the cosmic fabric, from the distant galaxy. It was a century ago that Albert Einstein predicted that space and time could shake like a bowl of jelly when massive things like black holes moved around. But such waves were finally confirmed only in 2016, when LIGO recorded the sound of two giant black holes colliding, causing a sensation that eventually led this month to a Nobel Prize https://www.nytimes.com/2017/10/03/science/nobel-prize-physics.html. …For the researchers, this is in some ways an even bigger bonanza than the original discovery. This is the first time they have discovered anything that regular astronomers could see and study…. https://www.nytimes.com/2017/10/16/science/ligo-neutron-stars-collision.html See also Quanta Magazine: Neutron-Star Collision Shakes Space-Time and Lights Up the Sky by Ana Kova.
2017-06-28. Greetings, E.T. (Please Don’t Murder Us). By Steven Johnson, The New York Times. Excerpt: On Nov. 16, 1974, a few hundred astronomers, government officials and other dignitaries gathered in the tropical forests of Puerto Rico’s northwest interior, a four-hour drive from San Juan. The occasion was a rechristening of the Arecibo Observatory, at the time the largest radio telescope in the world. The mammoth structure — an immense concrete-and-aluminum saucer as wide as the Eiffel Tower is tall, planted implausibly inside a limestone sinkhole in the middle of a mountainous jungle — had been upgraded to ensure its ability to survive the volatile hurricane season and to increase its precision tenfold. To celebrate the reopening, the astronomers who maintained the observatory decided to take the most sensitive device yet constructed for listening to the cosmos and transform it, briefly, into a machine for talking back. …the public-address system blasted nearly three minutes of two-tone noise through the muggy afternoon heat. To the listeners, the pattern was indecipherable, but somehow the experience of hearing those two notes oscillating in the air moved many in the crowd to tears. That 168 seconds of noise, now known as the Arecibo message, was the brainchild of the astronomer Frank Drake, then the director of the organization that oversaw the Arecibo facility. The broadcast marked the first time a human being had intentionally transmitted a message targeting another solar system. The engineers had translated the missive into sound, so that the assembled group would have something to experience during the transmission. But its true medium was the silent, invisible pulse of radio waves, traveling at the speed of light…. https://www.nytimes.com/2017/06/28/magazine/greetings-et-please-dont-murder-us.html
2016-06-02. Universe expanding faster than expected. By Robert Sanders, UC Berkeley News. Excerpt: Astronomers have obtained the most precise measurement yet of how fast the universe is expanding, and it doesn’t agree with predictions based on other data and our current understanding of the physics of the cosmos. The discrepancy — the universe is now expanding 9 percent faster than expected — means either that measurements of the cosmic microwave background radiation are wrong, or that some unknown physical phenomenon is speeding up the expansion of space, the astronomers say. …By measuring about 2,400 Cepheid stars in 19 nearby galaxies and comparing the apparent brightness of both types of stars, the researchers accurately determined the true brightness of the Type Ia supernovae. They then used this calibration to calculate distances to roughly 300 Type Ia supernovae in far-flung galaxies. “We needed both the nearby Cepheid distances for galaxies hosting Type Ia supernovae and the distances to the 300 more-distant Type Ia supernovae to determine the Hubble constant,” Filippenko said. “The paper focuses on the 19 galaxies and getting their distances really, really well, with small uncertainties, and thoroughly understanding those uncertainties.”… http://news.berkeley.edu/2016/06/02/universe-expanding-faster-than-expected/ 0
2015-10-22. Hubble spies Big Bang frontiers. NASA heic1523 — Science Release. Excerpt: Observations by the NASA/ESA Hubble Space Telescope have taken advantage of gravitational lensing to reveal the largest sample of the faintest and earliest known galaxies in the Universe. Some of these galaxies formed just 600 million years after the Big Bang and are fainter than any other galaxy yet uncovered by Hubble. …light from these galaxies took over 12 billion years to reach the telescope, allowing the astronomers to look back in time when the universe was still very young. …Johan Richard from the Observatoire de Lyon, France, points out, “The faintest galaxies detected in these Hubble observations are fainter than any other yet uncovered in the deepest Hubble observations.” …the team discovered that the accumulated light emitted by these galaxies could have played a major role in one of the most mysterious periods of the Universe’s early history — the epoch of reionisation. Reionisation started when the thick fog of hydrogen gas that cloaked the early Universe began to clear. Ultraviolet light was now able to travel over larger distances without being blocked and the Universe became transparent to ultraviolet light…. http://www.spacetelescope.org/news/heic1523/ See also: Hubble Uncovers Fading Cinders of Some of Our Galaxy’s Earliest Homesteaders (2015 Nov 5; HubbleSite News Release Number: STScI-2015-38)
2015-06-17. Traces of Earliest Stars That Enriched Cosmos Are Spied. By Dennis Overbye, New York Times. Excerpt: Astronomers said Wednesday that they had discovered a lost generation of monster stars that ushered light into the universe after the Big Bang and jump-started the creation of the elements needed for planets and life before disappearing forever. …in the aftermath of the Big Bang only hydrogen, helium and small traces of lithium were available to make the first stars. Such stars could have been hundreds or thousands of times as massive as the sun, according to calculations, burning brightly and dying quickly, only 200 million years after the universe began. Their explosions would have spewed into space the elements that started the chain of thermonuclear reactions by which subsequent generations of stars have gradually enriched the cosmos with elements like oxygen, carbon and iron. …in a paper to be published in The Astrophysical Journal, an international crew of astronomers led by David Sobral of the University of Lisbon, in Portugal, and the Leiden Observatory, in the Netherlands, said they had spotted the signature of these first-generation stars in a recently discovered galaxy that existed when the universe was only about 800 million years old. …The galaxy, known as CR7, is three times as luminous as any previously found from that time, the authors said. Within it is a bright blue cloud that seems to contain only hydrogen and helium…. http://www.nytimes.com/2015/06/18/science/space/astronomers-report-finding-earliest-stars-that-enriched-cosmos.html
2014-09-03. The Laniakea supercluster of galaxies. For GSS A Changing Cosmos chapter 9. Abstract excerpt: Galaxies congregate in clusters and along filaments, and are missing from large regions referred to as voids. These structures are seen in maps derived from spectroscopic surveys that reveal networks of structure that are interconnected with no clear boundaries. Extended regions with a high concentration of galaxies are called ‘superclusters’, although this term is not precise. …We define a supercluster to be the volume within such a surface, and so we are defining the extent of our home supercluster, which we call Laniakea…. http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. By R. Brent Tully et al, Nature 513. See also article in Huffington Post – http://www.huffingtonpost.com/2014/09/05/laniakea-supercluster-galaxy-tully_n_5763274.html
2014-03-17. Gravitational Waves from Big Bang Detected. Excerpt: Physicists have found a long-predicted twist in light from the big bang that represents the first image of ripples in the universe called gravitational waves, researchers announced today. The finding is direct proof of the theory of inflation, the idea that the universe expanded extremely quickly in the first fraction of a nanosecond after it was born. What’s more, the signal is coming through much more strongly than expected, ruling out a large class of inflation models and potentially pointing the way toward new theories of physics, experts say. “This is huge,” says Marc Kamionkowski…“It’s not every day that you wake up and find out something completely new about the early universe. To me this is as Nobel Prize–worthy as it gets.” …researchers have reported a surprisingly large number for r, the ratio of the gravitational wave fluctuations in the CMB to the fluctuations caused by perturbations in the density of matter. …Such a high value of r, for instance, indicates that inflation began even earlier than some models predicted, at one trillionth of a trillionth of a trillionth of a second after the big bang. The timing of inflation, in turn, tells physicists about the energy scale of the universe when inflation was going on. BICEP2’s value of r suggests that this was the same energy scale at which all the forces of nature except gravity (the electromagnetic, strong and weak forces) might have been unified into a single force—an idea called grand unified theory. The finding bolsters the idea of grand unification and rules out a number of inflation models that do not feature such an energy scale. …“This measurement is allowing us to use the early universe as a lab for new physics in energy ranges that are otherwise inaccessible to us,” Kamionkowski says. http://www.scientificamerican.com/article/gravity-waves-cmb-b-mode-polarization/. Clara Moskowitz, Scientific American. See also: http://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html and http://www.nytimes.com/2014/03/25/science/space/ripples-from-the-big-bang.html
2013-10-25. Earliest Known Galaxy Formed Stars at a Breakneck Pace. Excerpt: In the beginning was the big bang; then, hundreds of millions of years later, the universe was full of galaxies. This week, astronomers report taking another step into the unexplored time in between: They have imaged the earliest galaxy yet, dating from just 700 million years after the big bang. The galaxy—one of dozens imaged in a Hubble Space Telescope survey designed to pick up faint, distant galaxies—is aglow with hot, newborn stars, the researchers say, pointing to a rate of star formation that they estimate to be a hundred times that of the modern Milky Way. The find may offer a glimpse of an unexpected period of frenetic star birth in the early universe…. http://www.sciencemag.org/content/342/6157/411.short. Yudhijit Bhattacharjee, Science.
2013-03-20. Planck Mission Brings Universe into Sharp Focus | NASA RELEASE: 13-079. Excerpt: …The Planck space mission has released the most accurate and detailed map ever made of the oldest light in the universe, …. The map results suggest the universe is expanding more slowly than scientists thought, and is 13.8 billion years old, 100 million years older than previous estimates. The data also show there is less dark energy and more matter, both normal and dark matter, in the universe than previously known. …Planck launched in 2009 and has been scanning the skies ever since, mapping the cosmic microwave background, the afterglow of the theorized big bang that created our universe. This relic radiation provides scientists with a snapshot of the universe 370,000 years after the big bang. Light existed before this time, but it was locked in a hot plasma similar to a candle flame, which later cooled and set the light free. …The newly estimated expansion rate of the universe, known as Hubble’s constant, is 67.15 plus or minus 1.2 kilometers/second/megaparsec. …The new estimate of dark matter content in the universe is 26.8 percent, up from 24 percent, while dark energy falls to 68.3 percent, down from 71.4 percent. Normal matter now is 4.9 percent, up from 4.6 percent. …For more information about Planck, visit: http://www.nasa.gov/planck and http://www.esa.int/Our_Activities/Space_Science/Planck …. See full article at http://www.nasa.gov/home/hqnews/2013/mar/HQ_13-079_Planck_Mission.html.
2008 Aug 18. The Struggle to Measure Cosmic Expansion. By DENNIS OVERBYE, NY Times. Excerpt: Hoping to understand why the universe seems to be coming apart at its seams, a young astronomer and his colleagues have embarked on one of the oldest quests in cosmology, to measure how fast the universe is growing, how big it is and how old it is. That information is encoded in the value of an elusive number known as the Hubble constant that has led astronomers on a merry chase for three-quarters of a century. “It is the most fundamental number in cosmology,” said Adam Riess, 38, an astronomer at the Space Telescope Science Institute and Johns Hopkins University, and one of the discoverers 10 years ago that some kind of “dark energy” is speeding up the expansion of the universe.
This spring, in what he called “a triumph of metrology,” Dr. Riess announced that he and his comrade, Lucas Macri of Texas A&M University, had used the Hubble Space Telescope to make the newest and most precise measurement yet of this parameter.
Expressed in the quaint terms astronomers favor, the Hubble constant, Dr. Riess reported, is 74 kilometers per second per megaparsec. It means that for every additional million parsecs (about 3.26 million light-years) a galaxy is from us, it is going 74 kilometers per second faster. … with…an uncertainty of only 4.3 percent.
Only 30 years ago, distinguished astronomers could not agree within a factor of two on the value of Hubble’s constant, leaving every other parameter in cosmology uncertain by at least the same factor and provoking snickers from other fields of science.
…Dr. Riess’s distance ladder has only three rungs and one telescope, leaping from the Milky Way’s neighborhood to supernova explosions as distant as a billion light-years.
It starts with a galaxy known as NGC 4258 (a k a Messier 106 in Ursa Major), where astronomers have found clouds emitting radio waves at a frequency characteristic of water vapor circling the center of the galaxy, as well as the all-important Cepheid stars. By tracking the speeds and motion across the sky of these clouds with high resolution radio observations, a team led by James Herrnstein of the National Radio Astronomy Observatory in Socorro, N.M., in 1999 determined its distance as 23.5 million light-years.
Knowing the distance to that galaxy allowed Dr. Riess and his team to calibrate the Cepheids, which they then used to calibrate supernovas….
2008 May. Underground Astronomy. By Kathleen M. Wong, ScienceMatters@Berkeley. Excerpt: Most scientists who study the cosmos keep their eyes fastened firmly on the sky. Not so Bernard Sadoulet. A Berkeley professor of physics, Sadoulet is stalking dark matter, the elusive material that forms the scaffolding of the universe. And the place he’s laid his traps is just as shadowy-a former iron mine more than 2,300 feet underground.
Speculations about dark matter’s identity range from the side effects of additional dimensions to ultralight particles known as neutrinos. But several lines of thinking have converged on heavy particles known as WIMPs (weakly interacting massive particles).
“If these particles are the dark matter, they form a dark halo around the galaxy. We are in this halo, and there are billions of these particles going through us all the time,” Sadoulet says.
Sadoulet leads an experiment to find these particles within Minnesota’s Soudan Mine. His Cryogenic Dark Matter Search employs detectors made of silicon or germanium crystals cooled to nearly absolute zero.
“Within five years, three totally different approaches to catching WIMPS should be in operation, and we may be at the brink of a discovery” says Sadoulet. “It’s an interesting time to be searching for dark matter.”
2008 Jan 4. NASA Scientists Identify Smallest Known Black Hole. NASA Release No. 08-28. Excerpt: GREENBELT, Md. – Using a new technique, two NASA scientists have identified the lightest known black hole. With a mass only about 3.8 times greater than our Sun and a diameter of only 15 miles, the black hole lies very close to the minimum size predicted for black holes that originate from dying stars.
“This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question,” says lead author Nikolai Shaposhnikov of NASA’s Goddard Space Flight Center in Greenbelt, Md.
…lowest-mass known black hole belongs to a binary system named XTE J1650-500…