EF5C. Stay Current—What Is Light?

2023-05-09. Eavesdropping on the Vibrations of Earth’s Magnetic Bubble. [https://eos.org/articles/eavesdropping-on-the-vibrations-of-earths-magnetic-bubble] By Erin Martin-Jones, Eos/AGU. Excerpt: A NASA-funded crowdsourced science project has converted the unheard sounds resonating inside Earth’s magnetic shield into audible tracks, revealing an orchestra of whistles, wooshes, and chirps. …charged particles expelled from the Sun and lofted along by solar winds…can send ultralow-frequency waves quivering along the magnetic field lines that surround our planet—just like a harp string when plucked. This haunting melody is too low in pitch for us to hear, but researchers have turned these sounds into something audible and are now asking the public to help listen to the din of space….

2023-02-16. New Auroras Found Glowing in the Skies of Jupiter’s Moons. [https://www.nytimes.com/2023/02/16/science/auroras-jupiter-moons.html] By Robin George Andrews, The New York Times. Excerpt: New research shows auroras can also be seen on the Galilean moons of Jupiter: hypervolcanic Io, icy Europa, quirky Callisto and gigantic Ganymede. …other than Ganymede, the big moons of Jupiter lack magnetic bubbles. Instead, their auroras owe their existence to Io. Its noxious atmosphere — partly supplied by the moon’s epic volcanic eruptions — regularly sheds into space. The castoffs mingle with sunlight and become electrically excited. Plenty gets captured by Jupiter’s colossal magnetic bubble, but some of it slams back into Io’s atmosphere, or into the other three moons’ gassy sheaths. Those impacts are what ignite the moons’ auroral lights….

2021-02-09. Ham Radio Forms a Planet-Sized Space Weather Sensor Network. By Kristina Collins, David Kazdan, and Nathaniel A. Frissell, Eos/AGU. Excerpt: For researchers who monitor the effects of solar activity on Earth’s atmosphere, telecommunications, and electrical utilities, amateur radio signals a golden age of crowdsourced science. Space weather events, triggered by solar emissions and their interactions with Earth’s atmosphere, can have significant effects on communications and navigation technology and on electric power systems. As with terrestrial weather events, the economic impacts of space weather–related disruptions can be substantial, affecting satellite systems as well as systems on the ground. A severe geomagnetic storm (on the order of the Carrington Event of 1859) could have a catastrophic effect on modern infrastructure. …The Ham Radio Science Citizen Investigation (HamSCI) is a collective that unites amateur radio operators with the research community in the space and atmospheric sciences. This confederation of scientists, engineers, and hobbyists holds annual workshops during which ham radio operators and space scientists share findings. A new HamSCI effort, the Personal Space Weather Station project, aims to develop a robust and scalable network of amateur stations that will allow amateurs to collect useful data for space science researchers. The next HamSCI workshop will be held virtually 19–21 March 2021, and it will focus on midlatitude ionospheric measurements…. [https://eos.org/features/ham-radio-forms-a-planet-sized-space-weather-sensor-network]

2020-12-21.  Habitability and the Evolution of Life Under Our Magnetic Shield. By Manasvi Lingam, Eos/AGU. Excerpt: …The existence of a global magnetic field raises questions about how it affects habitability and life. This is a question wide in scope, and the discussion here is limited to only a couple of salient effects. It is commonly thought that magnetic fields are necessary to protect planetary atmospheres from erosion by the solar wind, which hastens the acceleration and escape of atmospheric particles through electromagnetic interactions. But how valid is this premise? …There is promising evidence that Earth’s geodynamo initiated as early as 4.2 billion years ago and that the crystallization of Earth’s inner core, which paved the way for the geodynamo of today, occurred more than half a billion years ago. Although the changes in Earth’s magnetic field wrought by these transitions were likely profound, the concomitant effects on our planet’s biosphere are much less clear. Earth’s organisms must have been affected to some degree, but fathoming the magnitude and nature of these repercussions necessitates further research synthesizing knowledge from geology, astronomy, plasma physics, microbiology, evolutionary biology, and other disciplines. By resolving the riddle of whether Earth’s magnetic field played a significant role in modulating the evolution of life, we will be better positioned to consider the related question of whether a magnetic field is necessary for a planet to be habitable in the first place…. [https://eos.org/science-updates/habitability-and-the-evolution-of-life-under-our-magnetic-shield]  See also The Herky-Jerky Weirdness of Earth’s Magnetic Field  and A Field Guide to the Magnetic Solar System

2019-12-27. Ancient Assyrian Aurorae Help Astronomers Understand Solar Activity. By Mara Johnson-Groh, Eos/AGU. Excerpt: Records of aurorae in Mesopotamia from 2,600 years ago are helping astronomers understand and predict solar activity today. …The Assyrian record is thought to be one of the earliest known observations of aurorae, dating to around 660 BCE. Aurorae are created by high-energy particles launched from the Sun, and historical records offer a way to study conditions on the Sun long before the invention of telescopes. …Documenting aurorae helps astronomers understand patterns of solar activity. …A major signature of pyroCbs is their impact on the stratosphere. But until recently, scientists didn’t think wildfires could inject soot, aerosols, and organic compounds high into the atmosphere.

2019-03-04. How Did We Miss This? An Upper Atmospheric Discovery Named STEVE. By Bea Gallardo-Lacourt, Gareth W. Perry, William E. Archer, and Eric Donovan, Eos/AGU. Excerpt: On 15 January 2016, highly skilled auroral photographers and citizen scientists of the Facebook group Alberta Aurora Chasers shared photographs of a unique optical form with Elizabeth MacDonald, a NASA space weather scientist and the creator of the aurora reporting website Aurorasaurus, and Eric Donovan, an expert in auroral physics at the University of Calgary. The pictures featured ribbons of white and mauve hues in the sky. Seen with the naked eye or through true-color imaging, the feature’s emissions and morphology are striking in how they stand apart from any other optical phenomena in the region. The strange sight had been documented for decades by amateur auroral photographers but had not yet been noticed by the scientific community….

2018-04-04. An Aurora of a Different Color. By Kimberly M. S. Cartier, AGU-Eos. Excerpt: Strong Thermal Emission Velocity Enhancement (STEVE) paints a green and purple streak across the sky from the bottom left to top right in the image above. In this image, this rare aurora-like event is crisscrossed by the dusty band of the Milky Way, which curves from the top left to bottom right. STEVE, captured, in this instance, last year at Childs Lake in Manitoba, Canada, is not an aurora in the traditional sense: Instead of the oval-shaped, blue/green glow of more common types of auroras, STEVE appears as a thin, purple streak dangling a wavy, green picket fence structure. STEVEs always appear at the same time as normal auroras, but they occur at lower latitudes, in an area of the atmosphere called the subauroral zone. …New insight into the origin and behavior of this rare atmospheric event became possible when, in 2016, a team of amateur and professional scientists used ground- and space-based cameras to image STEVE and a simultaneous normal aurora. By combining all of the available images, the team discovered that STEVEs and auroras form from a similar process—charged particles interacting with Earth’s magnetic field—but the particles that create STEVEs travel along magnetic field lines much closer to Earth than those that make ordinary auroras. That’s why STEVEs occur at lower latitudes than auroras….  https://eos.org/articles/an-aurora-of-a-different-color

2008 Jul 24. NASA Satellites Discover What Powers Northern Lights. NASA RELEASE: 08-185. Excerpt: GREENBELT, Md. — Researchers using a fleet of five NASA satellites have discovered that explosions of magnetic energy a third of the way to the moon power substorms that cause sudden brightenings and rapid movements of the aurora borealis, called the Northern Lights. The culprit turns out to be magnetic reconnection, a common process that occurs throughout the universe when stressed magnetic field lines suddenly snap to a new shape, like a rubber band that’s been stretched too far. “We discovered what makes the Northern Lights dance,” said Dr. Vassilis Angelopoulos of the University of California, Los Angeles. Angelopoulos is the principal investigator for the Time History of Events and Macroscale Interactions during Substorms mission, or THEMIS….

2008 Mar 20. SPRING IS AURORA SEASON. NASA Earth Observatory News. For reasons not fully understood by scientists, the weeks around the vernal equinox are prone to Northern Lights. In other words, spring is aurora season. Observations from NASA spacecraft are shedding new light on this old mystery.

2007 December 11. THEMIS Discoveries. A fleet of NASA spacecraft, launched less than eight months ago, has made three important discoveries about spectacular eruptions of Northern Lights called “substorms” and the source of their power. NASA’s Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission observed the dynamics of a rapidly developing substorm, confirmed the existence of giant magnetic ropes and witnessed small explosions in the outskirts of Earth’s magnetic field. The discoveries began on March 23, when a substorm erupted over Alaska and Canada, producing vivid auroras for more than two hours. A network of ground cameras organized to support THEMIS photographed the display from below while the satellites measured particles and fields from above. “The substorm behaved quite unexpectedly,” says Vassilis Angelopoulos, the mission’s principal investigator at the University of California, Los Angeles. “The auroras surged westward twice as fast as anyone thought possible, crossing 15 degrees of longitude in less than one minute. The storm traversed an entire polar time zone, or 400 miles, in 60 seconds flat.” …Angelopoulos was quite impressed with the substorm’s power and he estimated the total energy of the two-hour event at five hundred thousand billion Joules. That’s equivalent to the energy of one magnitude 5.5 earthquake . Where does all that energy come from? 
THEMIS may have found the answer. “The satellites have found evidence of magnetic ropes connecting Earth’s upper atmosphere directly to the sun,” said David Sibeck, 
project scientist for the mission at NASA’s Goddard Space Flight Center, Greenbelt, Md. “We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras.”
A magnetic rope is a twisted bundle of magnetic fields organized much like the twisted hemp of a mariner’s rope. Spacecraft have detected hints of these ropes before, but a single spacecraft was insufficient to map their 3D structure. THEMIS’ five identical micro-satellites 
were able to perform the feat. “THEMIS encountered its first magnetic rope on May 20,” said Sibeck.”It was very large, about as wide as Earth, and located approximately 
40,000 miles (70,000 km) above Earth’s surface in a region called the magnetopause.” The magnetopause is where the solar wind and Earth’s magnetic field meet and push against one another like sumo wrestlers locked in combat. There, the rope formed and unraveled in just a few minutes, providing a brief but significant conduit for solar wind energy…

2004 July 13. Will Compasses Point South?. By WILLIAM J. BROAD — The Earth’s magnetic field is collapsing and may eventually reappear with opposite polarity. But what effect will that have on us?

2003 December 3. Cracks in the Earth’s Magnetic Sheild – California-sized cracks in our planet’s magnetic field can remain open for hours, allowing the solar wind to gush through and power stormy space weather–this according to new observations from Earth-orbiting satellites.