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December 31, 2014April 26, 2016 by Bob King

Moonlight Is a Many-Splendored Thing

We see the Moon differently depending upon the wavelength in which we view it. Top row from left:

“By the Light of the Silvery Moon” goes the song. But the color and appearance of the Moon depends upon the particular set of eyes we use to see it. Human vision is restricted to a narrow slice of the electromagnetic spectrum called visible light.

With colors ranging from sumptuous violet to blazing red and everything in between, the diversity of the visible spectrum provides enough hues for any crayon color a child might imagine. But as expansive as the visual world’s palette is, it’s not nearly enough to please astronomers’ retinal appetites.

Visible light is a sliver of light's full range of "colors" which span from kilometers-long, low-energy radio waves (left) to short wavelength, energetic gamma rays. It's all light, with each color determined by wavelength. Familiar objects along the bottom reference light wave sizes. Visible light waves are about one-millionth of a meter wide. Credit: NASA — Visible light is a sliver of light’s full range of “colors” which span from kilometers-long, low-energy radio waves (left) to short wavelength, energetic gamma rays. It’s all light, with each color determined by wavelength. Familiar objects along the bottom reference light wave sizes. Visible light waves are about one-millionth of a meter wide. Credit: NASA

Since the discovery of infrared light by William Herschel in 1800 we’ve been unshuttering one electromagnetic window after another. We build telescopes, great parabolic dishes and other specialized instruments to extend the range of human sight. Not even the atmosphere gets in our way. It allows only visible light, a small amount of infrared and ultraviolet and selective slices of the radio spectrum to pass through to the ground. X-rays, gamma rays and much else is absorbed and completely invisible.

Earth's atmosphere blocks a good portion of light's diversity from reaching the ground, the reason we launch rockets and orbiting telescopes into space. Large professional telescopes are often built on mountain tops above much of the atmosphere allowing astronomers to see at least some infrared light that is otherwise absorbed by air at lower elevations. Credit: NASA — Earth’s atmosphere blocks a good portion of light’s diversity from reaching the ground, the reason we launch rockets and orbiting telescopes into space. Large professional telescopes are often built on mountain tops above much of the denser, lower atmosphere. This expands the viewing “window” into the infrared. Credit: NASA

To peer into these rarified realms, we’ve lofting air balloons and then rockets and telescopes into orbit or simply dreamed up the appropriate instrument to detect them. Karl Jansky’s homebuilt radio telescope cupped the first radio waves from the Milky Way in the early 1930s; by the 1940s sounding rockets shot to the edge of space detected the high-frequency sizzle of X-rays. Each color of light, even the invisible “colors”, show us a new face on a familiar astronomical object or reveal things otherwise invisible to our eyes.

So what new things can we learn about the Moon with our contemporary color vision?

Radio: Made using NRAO’s 140-ft telescope in Green Bank, West Virginia. Blues and greens represent colder areas of the moon and reds are warmer regions. The left half of Moon was facing the Sun at the time of the observation. The sunlit Moon appear brighter than the shadowed portion because it radiates more heat (infrared light) and radio waves.

Submillimeter: Taken using the SCUBA camera on the James Clerk Maxwell Telescope in Hawaii. Submillimeter radiation lies between far infrared and microwaves. The Moon appears brighter on one side because it’s being heated by Sun in that direction. The glow comes from submillimeter light radiated by the Moon itself. No matter the phase in visual light, both the submillimeter and radio images always appear full because the Moon radiates at least some light at these wavelengths whether the Sun strikes it or not.

Mid-infrared: This image of the Full Moon was taken by the Spirit-III instrument on the Midcourse Space Experiment (MSX) at totality during a 1996 lunar eclipse. Once again, we see the Moon emitting light with the brightest areas the warmest and coolest regions darkest. Many craters look like bright dots speckling the lunar disk, but the most prominent is brilliant Tycho near the bottom. Research shows that young, rock-rich surfaces, such as recent impact craters, should heat up and glow more brightly in infrared than older, dust-covered regions and craters. Tycho is one of the Moon’s youngest craters with an age of just 109 million years.

Near-infrared: This color-coded picture was snapped just beyond the visible deep red by NASA’s Galileo spacecraft during its 1992 Earth-Moon flyby en route to Jupiter. It shows absorptions due to different minerals in the Moon’s crust. Blue areas indicate areas richer in iron-bearing silicate materials that contain the minerals pyroxene and olivine. Yellow indicates less absorption due to different mineral mixes.

Visible light: Unlike the other wavelengths we’ve explored so far, we see the Moon not by the light it radiates but by the light it reflects from the Sun.

The iron-rich composition of the lavas that formed the lunar “seas” give them a darker color compared to the ancient lunar highlands, which are composed mostly of a lighter volcanic rock called anorthosite.

Ultraviolet: Similar to the view in visible light but with a lower resolution. The brightest areas probably correspond to regions where the most recent resurfacing due to impacts has occurred. Once again, the bright rayed crater Tycho stands out in this regard. The photo was made with the Ultraviolet Imaging Telescope flown aboard the Space Shuttle Endeavour in March 1995.

X-ray: The Moon, being a relatively peaceful and inactive celestial body, emits very little x-ray light, a form of radiation normally associated with highly energetic and explosive phenomena like black holes. This image was made by the orbiting ROSAT Observatory on June 29, 1990 and shows a bright hemisphere lit by oxygen, magnesium, aluminum and silicon atoms fluorescing in x-rays emitted by the Sun. The speckled sky records the “noise” of distant background X-ray sources, while the dark half of the Moon has a hint of illumination from Earth’s outermost atmosphere or geocorona that envelops the ROSAT observatory.

Gamma rays: Perhaps the most amazing image of all. If you could see the sky in gamma rays the Moon would be far brighter than the Sun as this dazzling image attempts to show. It was taken by the Energetic Gamma Ray Experiment Telescope (EGRET). High-energy particles (mostly protons) from deep space called cosmic rays constantly bombard the Moon’s surface, stimulating the atoms in its crust to emit gamma rays. These create a unique high-energy form of “moonglow”.

Astronomy in the 21st century is like having a complete piano keyboard on which to play compared to barely an octave a century ago. The Moon is more fascinating than ever for it.

December 22, 2014December 23, 2015 by Jason Major

NASA’s NuSTAR Scans the Sun with X-ray Vision

The west limb of the Sun imaged by NuSTAR and SDO shows areas of high-energy x-rays above particularly active regions (NASA/JPL-Caltech/GSFC)

What if you had x-ray vision like Superman? Or if those funny-looking glasses they advertised in comic books in the 60s actually worked?* Then with those our Sun might look something like this, lighting up with brilliant flares of high-energy x-rays as seen by NASA’s super-sensitive NuSTAR Space Telescope (with a little help from SDO.)

The NuStar Space Telescope launched into Earth orbit by a Orbital Science Corp. Pegasus rocket, 2012. The Wolter telescope design images throughout a spectral range from 5 to 80 KeV. (Credit: NASA/Caltech-JPL) — The NuStar Space Telescope launched aboard a Orbital Sciences Pegasus rocket, on June 13, 2012. (Credit: NASA/Caltech-JPL)

Of course NASA’s orbiting NuSTAR x-ray telescope is not like a typical medical imaging system. Instead of looking for broken bones, NuSTAR (short for Nuclear Spectroscopic Telescope Array) is made to detect high-energy particles blasting across the Universe from exotic objects like supermassive black holes, pulsars, and supernovae.

But astronomers suggested turning NuSTAR’s gaze upon our own Sun to see what sorts of x-ray activity may be going on there.

“At first I thought the whole idea was crazy,” said Fiona Harrison, a Professor of Physics and Astronomy at Caltech and PI for the NuSTAR mission. “Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?”

As it turns out NuSTAR was able to reveal some very interesting features on the Sun, showing where the corona is being heated to very high temperatures. The image above shows NuSTAR’s first observations, overlaid onto data acquired by NASA’s Solar Dynamics Observatory.

NuSTAR data is shown in green and blue, revealing high-energy emission around – but not exactly aligned with – active regions on the Sun where solar plasma is being heated to more than 3 million degrees. The red represents ultraviolet light captured by SDO and shows material in the solar atmosphere at a slightly cooler 1 million degrees.

The west limb of the Sun imaged by NuSTAR and SDO shows areas of high-energy x-rays near active regions and coronal loops (NASA/JPL-Caltech/GSFC) — The NuSTAR data overlaid on the full disk SDO image, rotated so north on the Sun is up. (NASA/JPL-Caltech/GSFC)

Because the Sun isn’t terribly intense in high energy x-ray output it’s safe to observe it with NuSTAR — it’s not likely to burn out the telescope’s sensors. But what NuSTAR can detect may help astronomers determine the exact mechanisms behind the intense coronal heating that occurs in and above the Sun’s chromosphere. If so-called “nanoflares” — miniature and as-yet-invisible versions of solar flares — are responsible, for instance, NuSTAR might be able to catch them in action for the first time.

“NuSTAR will be exquisitely sensitive to the faintest X-ray activity happening in the solar atmosphere, and that includes possible nanoflares,” said David Smith, solar physicist and member of the NuSTAR team at the University of California, Santa Cruz.

In addition NuSTAR could potentially detect the presence of axions in the Sun’s core — hypothesized particles that may make up dark matter in the Universe.

NuSTAR may not be a “solar telescope” per se, but that won’t stop astronomers from using its unique abilities to learn more about the star we intimately share space with.

“NuSTAR will give us a unique look at the Sun, from the deepest to the highest parts of its atmosphere.”

– David Smith, solar physicist, University of California Santa Cruz

Probing Pluto’s Paltry Atmosphere Using A Solar Eclipse And Spacecraft

Artist's conception of the Pluto system from the surface of one of its moons. Credit: NASA, ESA and G. Bacon (STScI)

Pluto is so far away from us and so tiny that it’s hard to glean even basic facts about it. What is its tenuous atmosphere made of? And how to observe it during NASA’s New Horizons very brief flyby next July? A recent Johns Hopkins blog post explains how a careful maneuver post-Pluto will let investigators use the Sun to examine the dwarf planet’s true nature.

Investigators will use an instrument called Alice, an ultraviolet spectrometer, to look at the atmosphere around Pluto and its largest moon, Charon. Alice is capable of examining the gases in the atmosphere using a large “airglow” aperture (4 by 4 centimeters) and also using the Sun for observation with a smaller, 1-mm solar occultation channel.

“Once New Horizons flies past Pluto, the trajectory will conveniently (meaning, carefully planned for many years) fly the spacecraft through Pluto’s shadow, creating an effect just like a solar eclipse here on Earth,” wrote Joel Parker, New Horizons co-investigator, in a blog post.

“So we can (and will) just turn the spacecraft around and stare at the Sun, using Alice as it goes behind Pluto to measure how the Sun’s ultraviolet light changes as that light passes through deeper and deeper parts of Pluto’s atmosphere. This technique lets us measure the composition of Pluto’s atmosphere as a function of altitude.”

And guess where the technique was used not too long ago? Titan! That’s a moon of Saturn full of hydrocarbons and what could be a precursor chemistry to life. The moon is completely socked in with this orange haze that is intriguing. Scientists are still trying to figure out what it is made of — and also, to use our understanding of it to apply to planets outside our solar system.

When a huge exoplanet passes in front of its star, and it’s close enough to Earth, scientists are starting to learn how to ferret out information about its chemistry. This shows them what temperature the atmosphere is like and what it is made of, although it should be emphasized scientists are only starting on this work.

A composite image of Titan's atmosphere, created using blue, green and red spectral filters to create an enhanced-color view. Image Credit: NASA/JPL/Space Science Institute — A composite image of Titan’s atmosphere, created using blue, green and red spectral filters to create an enhanced-color view. Image Credit: NASA/JPL/Space Science Institute

The goal of performing these transit observations of Titan was to understand how haze on an exoplanet might blur the observations. From four passes with the Cassini spacecraft, the team (led by Tyler Robinson at NASA’s Ames Research Center) found that haze would make it difficult to get information from all but the upper atmosphere.

“An additional finding from the study is that Titan’s hazes more strongly affect shorter wavelengths, or bluer, colors of light,” NASA stated at the time. “Studies of exoplanet spectra have commonly assumed that hazes would affect all colors of light in similar ways. Studying sunsets through Titan’s hazes has revealed that this is not the case.”

The nature of Pluto will better come to light when New Horizons makes its pass by the planet in July 2015. Meanwhile, controllers are counting down the days until the spacecraft emerges from its last hibernation on Saturday (Dec. 6).

Source: Johns Hopkins Applied Physics Laboratory

November 25, 2014December 23, 2015 by Bob King

Astronomers Discover First Mulitiple-image Gravitationally-lensed Supernova

The four dots around the bright source, an elliptical galaxy, are multiple images of the new supernova taken with the Hubble Space Telescope between November 10-20, 2014. In the bottom image, the galaxy has been digitally removed to show only the supernova. The line segments are diffraction spikes from a nearby star. Credit: P.L. Kelly et. all

How about four supernovae for the price of one? Using the Hubble Space Telescope, Dr. Patrick Kelly of the University of California-Berkeley along with the GLASS (Grism Lens Amplified Survey from Space) and Hubble Frontier Fields teams, discovered a remote supernova lensed into four copies of itself by the powerful gravity of a foreground galaxy cluster. Dubbed SN Refsdal, the object was discovered in the rich galaxy cluster MACS J1149.6+2223 five billion light years from Earth in the constellation Leo. It’s the first multiply-lensed supernova every discovered and one of nature’s most exotic mirages.

The rich galaxy cluster MACS J1149+2223 gained notoriety in 2012 when the most distant galaxy when the most distant galaxy found to date was discovered there through gravitational lensing. — The lensed supernova was discovered far behind the rich galaxy cluster MACS J1149.6+2223. The cluster is one of the most massive known and gained notoriety in 2012 when astronomers harnessed its powerful lensing ability to uncover the most distant galaxy known at the time. Credit: NASA/ESA/M. Postman STScI/CLASH team

Gravitational lensing grew out of Einstein’s Theory of Relativity wherein he predicted massive objects would bend and warp the fabric of spacetime. The more massive the object, the more severe the bending. We can picture this by imagining a child standing on a trampoline, her weight pressing a dimple into the fabric. Replace the child with a 200-pound adult and the surface of the trampoline sags even more.

Massive objects like the sun and even the planets warp the fabric of space. Here a planet orbits the sun but does not fall in because of its sideways orbital motion. — Massive objects like the Sun and even the planets warp the fabric of space. Here a planet orbits the Sun but doesn’t fall in because of its sideways orbital motion.

Similarly, the massive Sun creates a deep, but invisible dimple in the fabric of spacetime. The planets feel this ‘curvature of space’ and literally roll toward the Sun. Only their sideways motion or angular momentum keeps them from falling straight into the solar inferno.

Curved space created by massive objects also bends light rays. Einstein predicted that light from a star passing near the Sun or other massive object would follow this invisible curved spacescape and be deflected from an otherwise straight path. In effect, the object acts as a lens, bending and refocusing the light from the distant source into either a brighter image or multiple and distorted images. Also known as the deflection of starlight, nowadays we call it gravitational lensing.

This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada

Simulation of distorted spacetime around a massive galaxy cluster over time

Turns out there are lots of these gravitational lenses out there in the form of massive clusters of galaxies. They contain regular matter as well as vast quantities of the still-mysterious dark matter that makes up 96% of the material stuff in the universe. Rich galaxy clusters act like telescopes – their enormous mass and powerful gravity magnify and intensify the light of galaxies billions of light years beyond, making visible what would otherwise never be seen.

Here we see a central slice of the MACS cluster. A massive elliptical galaxy is responsible for splitting SN Refsdal into four images. It also distorts and lenses the purple-toned spiral galaxy that's host to the supernova. Credit: — This cropped image shows the central slice of the MACS J1149 galaxy cluster. A massive elliptical galaxy lenses the light of SN Refsdal into four separate images. It also distorts the purplish spiral galaxy that’s host to the supernova. Credit: NASA/ESA/M. Postman STScI/CLASH team

Let’s return to SN Refsdal, named for Sjur Refsdal, a Norwegian astrophysicist who did early work in the field of gravitational lensing. A massive elliptical galaxy in the MACS J1149 cluster “lenses” the 9.4 billion light year distant supernova and its host spiral galaxy from background obscurity into the limelight. The elliptical’s powerful gravity’s having done a fine job of distorting spacetime to bring the supernova into view also distorts the shape of the host galaxy and splits the supernova into four separate, similarly bright images. To create such neat symmetry, SN Refsdal must be precisely aligned behind the galaxy’s center.

What looks like a galaxy with five nuclei really has just one (at center) surrounded by a mirage of four images of a distant quasar. The galaxy lies 400 million light years away; the quasar about 8 billion. Credit: NASA/ESA/Hubble

The scenario here bears a striking resemblance to Einstein’s Cross, a gravitationally lensed quasar, where the light of a remote quasar has been broken into four images arranged about the foreground lensing galaxy. The quasar images flicker or change in brightness over time as they’re microlensed by the passage of individual stars within the galaxy. Each star acts as a smaller lens within the main lens.

Color-composite image of lensing elliptical galaxy and distorted background host spiral (top).The green circles show the locations of images S1–S4, while another quadruply imaged segment of the spiral arm is marked in red. The bottom panels show two additional lensed images of the spiral host galaxy visible in the galaxy cluster field. Credit: S.L. Kelly et. all — Color-composite image of the lensing elliptical galaxy and distorted background host spiral (top). The green circles, S1-4, show the locations of the supernova images, while another quadruply imaged segment of the spiral arm is marked in red. The bottom panels show two additional lensed images of the spiral host galaxy visible in the galaxy cluster field. Talk about a funhouse mirror! Credit: P.L. Kelly/GLASS/Hubble Frontier Fields

Detailed color images taken by the GLASS and Hubble Frontier Fields groups show the supernova’s host galaxy is also multiply-imaged by the galaxy cluster’s gravity. According to their recent paper, Kelly and team are still working to obtain spectra of the supernova to determine if it resulted from the uncontrolled burning and explosion of a white dwarf star (Type Ia) or the cataclysmic collapse and rebound of a supergiant star that ran out of fuel (Type II).

The time light takes to travel to the Earth from each of the lensed images is different because each follows a slightly different path around the center of the lensing galaxy. Some paths are shorter, some longer. By timing the brightness variations between the individual images the team hopes to provide constraints not only on the distribution of bright matter vs. dark matter in the lensing galaxy and in the cluster but use that information to determine the expansion rate of the universe.

You can squeeze a lot from a cosmic mirage!

November 20, 2014December 23, 2015 by David Dickinson

A Thousand Days ‘Til Totality: Anticipating the 2017 Solar Eclipse

The total solar eclipse of November 2012 as seen from

Where will YOU be on August 21^st, 2017?

Astronomy is all about humility and thinking big in terms of space and time. It’s routine for astronomers to talk of comets on thousand year orbits, or stars with life spans measured in billions of years…

Yup, the lifespan of your average humanoid is indeed fleeting, and pales in comparison to the universe, that’s for sure. But one astronomical series that you can hope to live through is the cycle of eclipses.

I remember reading about the total solar eclipse of February 26^th, 1979 as a kid. Carter was in the White House, KISS was mounting yet another comeback, and Voyager 1 was wowing us with images of Jupiter. That was also the last total solar eclipse to grace mainland United States in the 20^th century.

But the ongoing “eclipse-drought” is about to be broken.

The path of totality across the United States on August 21st, 2017. Credit: Great American Eclipse.com.

One thousand days from this coming Monday, November 24^th on August 21^st 2017, the shadow of the Moon will touch down off of the Oregon coast and sweep eastward across the U.S. heartland before heading out to the Atlantic off of the coast of South Carolina. Millions live within a days’ drive of the 115 kilometre wide path, and the eclipse has the added plus of occurring at the tail end of summer vacation season. This also means that lots of folks will be camping and otherwise mobile with their RVs and able to journey to the event.

The Great American Eclipse of 2017 from Michael Zeiler on Vimeo.

This is also the last total solar eclipse to pass over any of the 50 United States since July 11^th, 1991, and the first eclipse to cross the contiguous United States from “sea to shining sea” since way back on June 8^th, 1918.

Think it’s too early to prepare? Towns across the path, including Hopkinsville, Kentucky and towns in Kansas and Nebraska are already laying plans for eclipse day. Other major U.S. cities, such as Nashville, Idaho Falls, and Columbia, South Carolina also lie along the path of totality, and the spectacle promises to spawn a whole new generation of “umbraphiles” or eclipse chasers.

A total solar eclipse is an unforgettable sight. But unlike a total lunar eclipse, which can be viewed from the moonward-facing hemisphere of the Earth, one generally has to journey to the narrow path of totality to see a total solar eclipse. Totality rarely comes to you.

Viewing — The Zeilers view the November 2013 eclipse from Africa. Credit: Michael Zeiler.

And don’t settle for a 99% partial eclipse just outside the path. “There’s no comparison between partial and total solar eclipses when it comes to sheer grandeur and beauty,” Michael Zeiler, longtime eclipse chaser and creator of the Great American Eclipse website told Universe Today. We witnessed the 1994 annular solar eclipse of the Sun from the shores of Lake Erie, and can attest that a 99% partial eclipse is still pretty darned bright!

There are two total solar eclipses remaining worldwide up until 2017: One on March 20^th, 2015 crossing the high Arctic, and another on March 9th 2016 over Southeast Asia. The 2017 eclipse offers a maximum of 2 minutes and 41 seconds of totality, and weather prospects for the eclipse in late August favors viewers along the northwestern portion of the track.

And though an armada of cameras will be prepared to capture the eclipse along its trek across the U.S., many veteran eclipse chasers suggest that first time viewers merely sit back and take in the moment. The onset of totality sees a bizarre sort of twilight fall across the landscape, as shadow bands skip across the countryside, temperatures drop, and wildlife is fooled into thinking that nightfall has come early.

And then, all too soon, the second set of blinding diamond rings burst through the lunar valleys, the eclipse glasses go back on, and totality is over. Which always raises the question heard throughout the crowd post-eclipse:

When’s the next one?

Well, the good news is, the United States will host a second total solar eclipse on April 8^th, 2024, just seven years later! This path will run from the U.S. Southwest to New England, and crisscross the 2017 path right around Carbondale, Illinois.

Will the woo that surfaced around the approach of Comet ISON and the lunar tetrad of “blood Moon eclipses” rear its head in 2017? Ah, eclipses and comets seem to bring ‘em out of the woodwork, and 2017 will likely see a spike in the talking-head gloom and doom videos ala YouTube. Some will no doubt cite the “perfection” seen during total solar eclipses as proof of divine inspiration, though this is actually just a product of our vantage point in time and space. In fact, annular eclipses are slightly more common than total solars in our current epoch, and will become more so as the Moon slowly recedes from the Earth. And we recently noted in our post on the mutual phenomena of Jupiter’s moons that solar eclipses very similar to those seen from the Earth can also be spied from Callisto.

Heads up to any future interplanetary eclipse resort developer: Callisto is prime real estate.

Forget Mars... "Get your ass to totality!" — Forget Mars… “Get your ass to totality!” Credit: Great American Eclipse.

The 2017 total solar eclipse across America will be one for the history books, that’s for sure.

So get those eclipse safety glasses now, and be sure to keep ‘em handy through 2017 and onward to 2024!

-Read Dave Dickinson’s eclipse-fueled science fiction tales Shadowfall and Exeligmos.

November 12, 2014December 23, 2015 by Elizabeth Howell

Jupiter’s Great Red Spot Gets Its Color From Sunlight, Study Suggests

Reprocessed view by Bjorn Jonsson of the Great Red Spot taken by Voyager 1 in 1979 reveals an incredible wealth of detail.

If it weren’t for the Sun, Jupiter’s Great Red Spot would be a much blander feature on the gas giant, a new study reveals. This stands apart from what most scientists think about why for why the spot looks so colorful: that there are features in the clouds that give it its distinctive shade.

The new data comes from observations with the Cassini spacecraft, combined with experiments in the lab. They conclude that the Red Spot’s immense height, combined with sunlight breaking apart the atmosphere there into certain chemicals, make the feature that red that is visible even in small telescopes.

“Our models suggest most of the Great Red Spot is actually pretty bland in color, beneath the upper cloud layer of reddish material,” said Kevin Baines, a Cassini team scientist based at NASA’s Jet Propulsion Laboratory in California, in a statement. “Under the reddish ‘sunburn’ the clouds are probably whitish or grayish.”

Jupiter’s Great Red Spot is a cyclone larger than two Earths. (photomontage ©Michael Carroll)

The lab experiments combined ammonia and acetylene gases (atmospheric components from Jupiter) with ultraviolet light (simulating what the Sun produces), which created a ruddy substance that matched observations made with the Cassini spacecraft back in 2000. They also tried breaking apart ammonium hydrosulfide, a common element in Jupiter’s high clouds, but the color produced was actually a bright green.

The Great Red Spot is a storm that has been raging on Jupiter since at least when telescopes were first used in the 1600s. Over the past few decades, its size has shrunk considerably –it’s now half of what historical measurements showed — but it is still much larger than Earth. Scientists are hoping the forthcoming Juno mission, which will arrive at Jupiter at 2016, will help learn more about what is going on.

Results were presented at the Division for Planetary Science of the American Astronomical Society’s annual meeting this week in Tucson, Arizona. A press release did not disclose publication plans or if the research is peer-reviewed.

Source: NASA

November 12, 2014December 23, 2015 by Bob King

Better than Bieber, Rosetta’s Comet Sings Strange, Seductive Song

Magnetic field lines bound up in the sun’s wind pile up and drape around a comet’s nucleus to shape the blue ion tail. Notice the oppositely-directed fields on the comet’s backside. The top set points away from the comet; the bottom set toward. In strong wind gusts, the two can be squeezed together and reconnect, releasing energy that snaps off a comet’s tail. Credit: Tufts University

Tune in to the song of Comet Churyumov-Gerasimenko

Scientists can’t figure exactly why yet, but Comet 67P/Churyumov-Gerasimenko has been singing since at least August. Listen to the video – what do you think? I hear a patter that sounds like frogs, purring and ping-pong balls. The song is being sung at a frequency of 40-50 millihertz, much lower than the 20 hertz – 20 kilohertz range of human hearing. Rosetta’s magnetometer experiment first clearly picked up the sounds in August, when the spacecraft drew to within 62 miles (100 km) of the comet. To make them audible Rosetta scientists increased their pitch 10,000 times.

The sounds are thought to be oscillations in the magnetic field around the comet. They were picked up by the Rosetta Plasma Consortium, a suite of five instruments on the spacecraft devoted to observing interactions between the solar plasma and the comet’s tenuous coma as well as the physical properties of the nucleus. A far cry from the stuff you donate at the local plasma center, plasma in physics is an ionized gas. Ionized means the atoms in the gas have lost or gained an electron through heating or collisions to become positively or negatively charged ions. Common forms of plasma include the electric glow of neon signs, lightning and of course the Sun itself.

Having lost their neutrality, electric and magnetic fields can now affect the motion of particles in the plasma. Likewise, moving electrified particles affect the very magnetic field controlling them.

Scientists think that neutral gas particles from vaporizing ice shot into the coma become ionized under the action of ultraviolet light from the Sun. While the exact mechanism that creates the curious oscillations is still unknown, it might have something to do with the electrified atoms or ions interacting with the magnetic fields bundled with the Sun’s everyday outpouring of plasma called the solar wind. It’s long been known that a comet’s electrified or ionized gases present an obstacle to the solar wind, causing it to drape around the nucleus and shape the streamlined blue-tinted ion or gas tail.

“This is exciting because it is completely new to us. We did not expect this, and we are still working to understand the physics of what is happening,” said Karl-Heinz Glassmeier, head of Space Physics and Space Sensorics at the Technical University of Braunschweig, Germany.

While 67P C-G’s song probably won’t make the Top 40, we might listen to it just as we would any other piece of music to learn what message is being communicated.

November 11, 2014December 23, 2015 by Elizabeth Howell

‘Not All Hope Is Lost’: NASA Sun Probe Silent Now For Six Weeks

Artist's conception of one of the Solar TErrestrial RElations Observatory (STEREO) spacecraft. Credit: NASA

No one knows exactly why a NASA solar probe stopped talking to Earth six weeks ago, but it’s possible the spacecraft is out of power and is drifting without a way of calling for help, the agency said in an update.

On Oct. 1, NASA suddenly lost contact with one of the two Solar TErrestrial RElations Observatory (STEREO) spacecraft, which are currently examining the far side of the Sun. The probes are considered crucial for solar forecasting, so the loss is a blow. While the STEREO-Behind probe has been mute since then, the agency says “not all hope is lost” for a recovery.

STEREO-Behind went silent after NASA deliberately reset the spacecraft. Along with its twin, STEREO-Ahead, in the coming years the spacecraft will need to reposition its antenna to avoid getting fried by the Sun. Also, there is a period where each spacecraft will need to work autonomously, because the Sun’s radio interference will make it difficult or impossible for communications to get through.

First complete image of the far side of the sun taken on June 1, 2011. Click image for larger version. Credit: NASA/STEREO.

To prepare the spacecraft, NASA has been testing them out ahead of these events, which are called “solar conjunction operations.” STEREO-Ahead passed the tests and entered these operations in August, where it will remain until 2016. STEREO-Behind was supposed to go into this phase on Dec. 1. Preparations started Sept. 27, when STEREO-Behind was put into the same safe mode test that was used on STEREO-Ahead.

“One part of this test was to observe the firing of the spacecraft hard command loss timer, which resets the spacecraft if no commands are received after three days,” NASA wrote in an update. “The purpose of this is to correct any problems that might be preventing the spacecraft from receiving commands from the ground. While the spacecraft is out of contact on the far side of the Sun, this reset will occur every three days.”

The timer did fire as planned on Oct. 1, and the spacecraft reset as expected. However, the radio signal coming from STEREO-Behind wasn’t as strong as expected. Then, it disappeared altogether.

An artist's concept shows both STEREO surrounding the sun on opposite sides. Credit: NASA — An artist’s concept shows both STEREO surrounding the sun on opposite sides. Credit: NASA

While there’s not much information to work with, NASA says it does know a few things. Before the reset, information or telemetry from the spacecraft showed it was working fine. After the reset, though, they could tell the inertial measurement unit (IMU) was turned on. This is unusual, and shows that the guidance system’s star tracker hadn’t picked up its guide stars as expected.

“This is not unexpected—there have been other occasions when it took the star tracker several minutes, or even a few days, to start determining the spacecraft orientation based on star images,” NASA said.

“In fact, on Sept. 28, as part of the same test sequence, the spacecraft was reset, and it took 12 minutes for the star tracker to start providing an attitude solution. When the star tracker is ofline, the spacecraft will automatically turn on the IMU to provide rotational rate information.”

Deployment of STEREO Spacecraft Panels. Credit: 2002-Johns Hopkins University Applied Physics Laboratory. Credit: Dr C.J.Eyles, University of Birmingham

NASA thinks the star tracker’s struggles would explain why the radio signal wasn’t as strong as expected, because the spacecraft’s high-gain antenna wasn’t aimed at Earth properly. But there’s more — it appears one of the IMU’s laser gyroscopes isn’t working and is giving “bad data to the attitude control system”, NASA said. So now the spacecraft was facing two failures, which is tough for it to deal with, the agency added.

Did the spacecraft recognize the problem? If it did, it would have used the last backup system — five solar aspect sensors — which should have made sure the solar panels were pointed in the right direction to provide power. If not, the spacecraft might have thought it was in a roll, turned on its thrusters, and then spun itself in such a way that it could have lost sunlight power.

NASA is trying to send out commands to address all of these failure possibilities, and it emphasizes that a recovery is still possible. The Solar and Heliospheric Observatory (SOHO), for example, also lost power in 1998 when a spin put its solar panels out of reach of the Sun. However, as its orbit changed, the Sun’s light eventually fell across the panels and power was restored. The spacecraft was recovered and still works today.

Source: NASA

November 6, 2014December 23, 2015 by David Dickinson

RAISE: How to Capture 1,500 Solar Images in a Five Minute Flight

RAISE in the cleanroom prior to launch. Credit: NASA/RAISE.

Quick: how do you aim an instrument at the Sun from a moving rocket on a fifteen minute suborbital flight?

The answer is very carefully, and NASA plans to do just that today, Thursday, November 6^th as the Rapid Acquisition Imaging Spectrograph Experiment, also known as RAISE, takes to the skies over White Sands, New Mexico, to briefly study the Sun.

Capturing five images per second, RAISE is expected to gather over 1,500 images during five minutes of data collection near apogee.

Why use sub-orbital sounding rockets to do observations of the Sun? Don’t we already have an armada of space and ground-based instruments to accomplish this that stare at our nearest star around the clock? Well, it turns out that sounding rockets are still cost-effective means of testing and demonstrating new technologies.

“Even on a five-minute flight, there are niche areas of science we can focus on well,” said solar scientist Don Hassler of the Southwest Research Institute in Boulder, Colorado in a recent press release. “There are areas of the Sun that need to be examined with the high-cadence observations that we can provide.”

Indeed, there’s a long history of studying the Sun by use of high-altitude sounding rockets, starting with the detection of solar X-rays by a detector placed in a captured V-2 rocket launched from White Sands in 1949.

Sub-orbital astronomy in 5 minutes: the flight of a sounding rocket. Credit: NASA.

RAISE will actually scrutinize an active region of the Sun turned Earthward during its brief flight to create what’s known as a spectrogram, or an analysis of solar activity at differing wavelengths. This gives scientists a three dimensional layered snapshot of solar activity, as different wavelengths correspond to varying velocities of solar material and wavelengths. Think of looking at layers of cake. This, in turn, paints a picture of how material is circulated and moved around the surface of the Sun.

This will be RAISE’s second flight, and this week’s launch will sport a brand new diffraction grating coated with boron carbide to enhance wavelength analysis. RAISE will also look at the Sun in the extreme ultraviolet which cannot penetrate the Earth’s lower atmosphere. Technology pioneered by missions such as RAISE may also make its way into space permanently on future missions, such as the planned European Space Agency and NASA joint Solar Orbiter Mission, set for launch in 2017. The Solar Orbit Mission will study the Sun close up and personal, journeying only 26 million miles or 43 million kilometres from its surface, well inside the perihelion of the planet Mercury.

“This is the second time we have flown a RAISE payload, and we keep improving it along the way,” Hassler continued. “This is a technology that is maturing relatively quickly.”

As you can imagine, RAISE relies on clear weather for a window to launch. RAISE was scrubbed for launch on November 3^rd, and the current window for launch is set for 2:07 PM EST/19:07 Universal Time, which is 12:07 PM MST local time at White Sands. Unlike the suborbital launches from Wallops Island, the White Sands launches aren’t generally carried live, though they tend to shut down US highway 70 between Las Cruces and Alamogordo that bisects White Sands just prior to launch.

Currently, the largest sunspot turned forward towards the Earth is active region 2205.

Another recent mission lofted by a sounding rocket to observe the Sun dubbed Hi-C was highly successful during its short flight in 2013.

RAISE will fly on a Black Brant sounding rocket, which typically reaches an apogee of 180 miles or 300 kilometres.

A look at recent solar activity coming around the solar limb to be targeted by RAISE. Credit: NASA/SDO

Unfortunately, the massive sunspot region AR2192 is currently turned away from the Earth and will effectively be out of RAISE’s view. The largest in over a decade, the Jupiter sized sunspot wowed viewers of the final solar eclipse of 2014 just last month. This large sunspot group will most likely survive its solar farside journey and reappear around the limb of the Sun sometime after November 9^th, good news if RAISE is indeed scrubbed today due to weather.

And our current solar cycle has been a very schizophrenic one indeed. After a sputtering start, solar cycle #24 has been anemic at best, with the Sun struggling to come out of a profound minimum, the likes of which hasn’t been seen in over a century. And although October 2014 produced a Jupiter-sized sunspot that was easily seen with eclipse glasses, you wouldn’t know that we’ve passed a solar maximum from looking at the Sun now. In fact, there’s been talk among solar astronomers that solar cycle #25 may be even weaker, or absent all together.

All this makes for fascinating times to study our sometimes strange star. RAISE observations will also be coordinated with views from the Solar Dynamics Observatory and the joint NASA-JAXA Hinode satellites in Earth orbit. We’ll also be at White Sands National Park today, hoping the get a brief view of RAISE as it briefly touches space.

It’s a great time for solar astronomy!

October 23, 2014December 23, 2015 by Nancy Atkinson

Beautiful Images of the October 23, 2014, Partial Solar Eclipse

The partial solar eclipse of October 23, 2014. Credit and copyright: Derek Mellott.

“The Sun looks like it has a bite taken out of it!” said one enthusiastic viewer of the partial solar eclipse on October 23. Although I only had my paper plate pinhole projector that I shared with a crowd of folks (you can see an image of it near the bottom of the images here), the funny-looking Sun projected onto the plate definitely looked like a cookie with bite out of it or a clipped fingernail. But thankfully, as the Moon moved in front of the Sun today, legions of astrophotographers were out to take fantastic images of the eclipse. And the gigantic sunspot named AR 2192 made a cameo appearance as well. Enjoy the gallery below!

Thanks to everyone who uploaded images to our Flickr page or shared their images on Twitter.

An artistic view of the Partial Solar Eclipse, October 23, 2014. Credit and copyright: A Nartist.

The setting Sun, shadowed by the Moon and spotted with intense magnetic activity on October 23, 2014. Credit and copyright: Tavi Greiner.

Solar eclipse over the Flatirons near Boulder, Colorado. A syzygy, with the Earth and Moon simultaneously transiting the Sun. Credit and copyright: Alex Parker.

Partial Solar Eclipse of October 23, 2014 at 280mm. Credit and copyright: Forrest Tanaka. — Partial Solar Eclipse of October 23, 2014, at 280mm. Credit and copyright: Forrest Tanaka.

The sun sets while still in eclipse as seen from Duluth, Minn. Thursday evening October 23. Credit and copyright: Bob King. — The sun sets while still in eclipse as seen from Duluth, Minn., Thursday evening October 23. Credit and copyright: Bob King.

The solar eclipse on October 23, 2014, showing the Sun dotted by sunspots and airplane contrails. Credit and copyright: Greg Hogan.

A cloudy closeup of the partial solar eclipse on October 23, 2014. Credit and copyright: JCC_Starguy on Flickr.

The cusps of the Sun's disk are just visible above the horizon as the solar eclipse of October 23, 2014 fades out over Iowa. Credit and copyright: Alan Boyle/NBC News. — The cusps of the Sun’s disk are just visible above the horizon as the solar eclipse of October 23, 2014, fades out over Iowa. Credit and copyright: Alan Boyle/NBC News.

A partial solar eclipse is visable just before sunset Thursday, Oct. 23, 2014, in Arlington, VA. Photo Credit: (NASA/Bill Ingalls)

The partial solar eclipse as viewed through a paper plate pinhole projector. Credit, copyright and pinhole: Nancy Atkinson.

OK, here’s what it looked like outside the SETI Institute. pic.twitter.com/ucqWzJeB4c

— SethShostak (@SethShostak) October 24, 2014

The Moon is beginning to eclipse an enormous filament on the Sun http://t.co/oFH0aPfEay via @Slooh pic.twitter.com/JbM3OHI4wQ

— Alan Duffy (@astroduff) October 23, 2014

What we did for fun… hundreds of crescent suns from a collapsible “spaghetti strainer” #eclipse: pic.twitter.com/ih9vvHUwMI

— David Dickinson (@Astroguyz) October 23, 2014

PHOTOS: Partial Solar Eclipse: https://t.co/nZowDIognC #SanJose #BayArea #SolarEclipse pic.twitter.com/Kdu4XIMoa0

— Chris Calubaquib (@ChrisAstro) October 24, 2014

See more great images on Universe Today’s Flickr pool page.