"The surface of the Earth is the shore of the cosmic ocean... Recently, we've managed to wade a little way out, and the water seems inviting." - Carl Sagan
Fresh crater exposing buried ice on Mars
A meteorite impact that excavated this crater on Mars exposed bright ice that had been hidden just beneath the surface at this location: latitude 43.9 degrees north, longitude 204.3 degrees east. The 100-meter scale bar at lower right is 109 yards.
Image credit: NASA/JPL-Caltech/Univ. of Arizona
Icy material thrown from cratering impact on Mars
This image taken on May 19, 2010, shows an impact crater that had not existed when the same location on Mars was previously observed in March 2008. The new impact excavated and scattered water ice that had been hidden beneath the surface.
Image credit: NASA/JPL-Caltech/Univ. of Arizona
NASA’s Juno gives starship-like view of Earth flyby
When NASA’s Juno spacecraft flew past Earth on Oct. 9, 2013, it received a boost in speed of more than 8,800 mph (about 3.9 kilometers per second), which set it on course for a July 4, 2016, rendezvous with Jupiter, the largest planet in our solar system. One of Juno’s sensors, a special kind of camera optimized to track faint stars, also had a unique view of the Earth-moon system. The result was an intriguing, low-resolution glimpse of what our world would look like to a visitor from afar.
"If Captain Kirk of the USS Enterprise said, ‘Take us home, Scotty,’ this is what the crew would see," said Scott Bolton, Juno principal investigator at the Southwest Research Institute, San Antonio. "In the movie, you ride aboard Juno as it approaches Earth and then soars off into the blackness of space. No previous view of our world has ever captured the heavenly waltz of Earth and moon."
The Juno Earth flyby movie is available at: http://www.youtube.com/watch?v=_CzBlSXgzqI&feature=youtu.be . The music accompaniment is an original score by Vangelis.
"With the Earth flyby completed, Juno is now on course for arrival at Jupiter on July 4, 2016," said Rick Nybakken, Juno project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
Image credit: NASA/JPL-Caltech
RIP Comet ISON: scientists declare famous ‘sungrazer’ dead after Sun encounter
It’s time to accept reality: Comet ISON is dead.
Comet ISON broke apart during its highly anticipated solar flyby on Nov. 28, emerging from behind the sun as a diffuse cloud of dust that has since all but dissipated in the darkness of deep space, scientists say.
"At this point, it seems like there’s nothing left," comet expert Karl Battams, of the U.S. Naval Research Laboratory in Washington, D.C., said here today at the annual meeting of the American Geophysical Union. "Comet ISON is dead; its memory will live on."
Comet ISON, which was discovered by two Russian amateur astronomers in September 2012, was making its first trip to the inner solar system from the distant and frigid Oort Cloud. The comet skimmed just 684,000 miles (1.1 million kilometers) above the surface of the sun on Nov. 28.
Comet ISON’s perilous journey was tracked closely by skywatchers, who hoped the icy wanderer would put on a great celestial show, and scientists, who watched the gases boiling off ISON to learn more about comet composition and structure.
Both groups had hoped the viewing campaign would last beyond perihelion, or closest approach, but Comet ISON couldn’t survive the sun’s intense heat and powerful gravitational pull.
"It looks like dust production more or less stopped when the comet reached perihelion," said Geraint Jones of University College London. "The comet continued to fade after perihelion, as it moved away from the sun."
ISON gave one tantalizing hint that it may still be intact, brightening considerably a few hours after the perihelion passage. But that may simply have been a consequence of orbital dynamics and nothing more, Jones said.
Comet ISON’s fragment cloud likely stretched out as the icy object reached perihelion, with the more anterior pieces speeding up relative to the ones farther behind, Jones explained. This would have caused ISON to dim, and then re-brighten briefly as the fragments clumped up again on the other side of the sun.
Comet behavior is incredibly difficult to predict, so it’s tough to know exactly why ISON didn’t make it. But its disintegration may have something to do with the comet’s relatively small size. Recent observations by NASA’s Mars Reconnaissance Orbiter (MRO) suggest that ISON’s nucleus was between 330 feet and 3,300 feet (100 to 1,000 meters) wide, scientists said today.
"It was probably smaller than maybe 600 meters [in] diameter," said Alfred McEwen of the University of Arizona, principal investigator of MRO’s powerful HiRISE camera. "And from past sungrazing comets, those smaller than about half a kilometer, they don’t survive."
While Battams and other experts have said their farewells to ISON, several NASA space telescopes will continue scanning the heavens just in case the comet makes a miraculous reappearance.
"NASA is going to try to look for it with Hubble, and I’ve heard that Spitzer and Chandra may be attempting observations as well," Battams said. "That really is sort of a recovery mission, but I don’t know if we’re going to get any success with those."
Image credit: Waldemar Skorupa
Unprecedented images of the Sun
The region located between the surface of the sun and its atmosphere has been revealed as a more violent place than previously understood, according to images and data from NASA’s newest solar observatory, the Interface Region Imaging Spectrograph, or IRIS.
Solar observatories look at the sun in layers. By capturing light emitted by atoms of different temperatures, they can focus in on different heights above the sun’s surface extending well out into the solar atmosphere, the corona. On June 27, 2013, IRIS, was launched, to study what’s known as the interface region - a layer between the sun’s surface and corona that previously was not well observed.
Over its first six months, IRIS has thrilled scientists with detailed images of the interface region, finding even more turbulence and complexity than expected. IRIS scientists presented the mission’s early observations at a press conference at the Fall American Geophysical Union meeting on Dec. 9, 2013.
"The quality of images and spectra we are receiving from IRIS is amazing," said Alan Title, IRIS principal investigator at Lockheed Martin in Palo Alto, Calif. "And we’re getting this kind of quality from a smaller, less expensive mission, which took only 44 months to build."
For the first time, IRIS is making it possible to study the explosive phenomena in the interface region in sufficient detail to determine their role in heating the outer solar atmosphere. The mission’s observations also open a new window into the dynamics of the low solar atmosphere that play a pivotal role in accelerating the solar wind and driving solar eruptive events.
Image source: NASA
Clay-like minerals found on icy crust of Europa
A new analysis of data from NASA’s Galileo mission has revealed clay-type minerals at the surface of Jupiter’s icy moon Europa that appear to have been delivered by a spectacular collision with an asteroid or comet. This is the first time such minerals have been detected on Europa’s surface. The types of space rocks that deliver such minerals typically also often carry organic materials.
"Organic materials, which are important building blocks for life, are often found in comets and primitive asteroids," said Jim Shirley, a research scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. "Finding the rocky residues of this comet crash on Europa’s surface may open up a new chapter in the story of the search for life on Europa," he said.
Many scientists believe Europa is the best location in our solar system to find existing life. It has a subsurface ocean in contact with rock, an icy surface that mixes with the ocean below, salts on the surface that create an energy gradient, and a source of heat (the flexing that occurs as it gets stretched and squeezed by Jupiter’s gravity). Those conditions were likely in place shortly after Europa first coalesced in our solar system.
Shirley and colleagues, funded by a NASA Outer Planets Research grant, were able to see the clay-type minerals called phyllosilicates in near-infrared images from Galileo taken in 1998. Those images are low resolution by today’s standards, and Shirley’s group is applying a new technique for pulling a stronger signal for these materials out of the noisy picture. The phyllosilicates appear in a broken ring about 25 miles (40 kilometers) wide, which is about 75 miles (120 kilometers) away from the center of a 20-mile-diameter (30 kilometers) central crater site.
The leading explanation for this pattern is the splash back of material ejected when a comet or asteroid hits the surface at an angle of 45 degrees or more from the vertical direction. A shallow angle would allow some of the space rock’s original material to fall back to the surface. A more head-on collision would likely have vaporized it or driven that space rock’s materials below the surface. It is hard to see how phyllosilicates from Europa’s interior could make it to the surface, due to Europa’s icy crust, which scientists think may be up to 60 miles (100 kilometers) thick in some areas.
Therefore, the best explanation is that the materials came from an asteroid or comet. If the body was an asteroid, it was likely about 3,600 feet (1,100 meters) in diameter. If the body was a comet, it was likely about 5,600 feet (1,700 meters) in diameter. It would have been nearly the same size as the comet ISON before it passed around the sun a few weeks ago.
"Understanding Europa’s composition is key to deciphering its history and its potential habitability," said Bob Pappalardo of JPL, the pre-project scientist for a proposed mission to Europa. "It will take a future spacecraft mission to Europa to pin down the specifics of its chemistry and the implications for this moon hosting life."
Image credit: NASA/JPL-Caltech/SETI
Milky Way and Bifrost Observatory
Image credit & copyright: Fred Espenak
Big Dipper and MAGIC Telescope
Stars of the constellation Ursa Major (the Big bear) form the familiar dipper-like asterism in the northern sky as photographed from the Roque de los Muchachos Observatory on the Canary island of La Palma. The starry night sky is reflected from one of a pair of 17 meter diameter, multi-mirrored MAGIC telescopes. The MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescope is intended to observe gamma rays indirectly by detecting brief flashes of optical light, called Cherenkov light.
Image credit & copyright: Babak Tafreshi
At the beginning of dawn the southern Milky Way is photographed over the Cerro Paranal Observatory in the barren Atacama Desert. Bright stars Alpha and Beta Centauri are near the horizon and the Southern Cross (Crux) appear above them. Higher in the sky is the large red emission Carina Nebula. The Large Magellanic Clouds is on the right. With its dark, steady, and transparent sky, Paranal is home to some of the world’s leading telescopes. Operated by the European Southern Observatory (ESO) the Very Large Telescope (VLT) is located on Paranal, composed of four 8-meter telescopes and smaller auxiliary telescopes, each 1.8 m in aperture (appear in this image), which are important elements of the VLT interferometer.
Image credit & copyright: Babak Tafreshi
Comet ISON as seen from the ISS
This image reveals a pin-head sized view of an object which is actually the comet ISON. Hardware components of the orbital outpost and Earth’s atmosphere above the horizon take up most of the image. Most of the other bright dots in the sky are heavenly bodies. The comet is distinguishable by its tail.
Image credit: ISS038-E-007980 (23 Nov. 2013)
Milky Way over the Dolomites photo by Max Rive
The fading beauty
At coast of the Mediterranean Sea in southeast Spain, the Milky Way fades in to light of nearby city of Mazarron, Murcia.
Image credit & copyright: Gernot Meiser
Sky of a lonely tree
The Milky Way appears over a hill-top lonely tree at the Atlantic coastline in Brittany, France. Light dome of a nearby town vanishes the night sky near the horizon. From the photographer: “It took me quite some time to find a suitable lonely tree in this country. I was there the day after the Autumn equinox. The rising Moon is illuminating the sky and the Earth.”
Image credit & copyright: Laurent Laveder
Towards the ocean
The Milky Way in the evening twilight appears over the Atlantic Ocean from the Pointe de Pen-Hir in the Brittany, France. A nearby town brightens the sky from behind the left side cliffs but the night sky towards the ocean is unspoiled of light pollution.
Image credit & copyright: Laurent Laveder