Children ice skating in Khakassia, Russia react to the fall of a bright fireball two nights ago on Dec.6 In 1908 it was Tunguska event, a meteorite exploded in mid-air, flattening 770 square miles of forest. 39 years later in 1947, 70 tons of iron meteorites pummeled the Sikhote-Alin Mountains, leaving more than 30 craters. […]
A new study reveals that Rosetta’s Comet likely spent billions of years chilling in the Kuiper Belt before chance interactions with Neptune and Jupiter wrangled it into the inner Solar System.
The post Astronomers Think They Know Where Rosetta’s Comet Came From appeared first on Universe Today.
Host: Fraser Cain (@fcain) Guests: Kimberly Cartier (@AstroKimCartier ) Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg ) Dave Dickinson (www.astroguyz.com / @astroguyz) Their stories this week: Blue Origin, take three! (And a SpaceX launch today) Japanese X-ray satellite NASA Announces new planet hunting instrument Weekend Occultations US Navy Resumes Celestial Navigation Training What Hit Jupiter? We’ve had […]
The post Weekly Space Hangout – Apr. 8, 2016: Space News Roundup appeared first on Universe Today.
All right, maybe not blinking like a flashlight (or a beacon on the tippity-top of a communication tower—don’t even start that speculation up) but the now-famous “bright spots” on the dwarf planet Ceres have been observed to detectably increase and decrease in brightness, if ever-so-slightly.
And what’s particularly interesting is that these observations were made not by NASA’s Dawn spacecraft, currently in orbit around Ceres, but from a telescope right here on Earth.
Researchers using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument on ESO’s 3.6-meter telescope at La Silla detected “unexpected” changes in the brightness of Ceres during observations in July and August of 2015. Variations in line with Ceres’ 9-hour rotational period—specifically a Doppler effect in spectral wavelength created by the motion of the bright spots toward or away from Earth—were expected, but other fluctuations in brightness were also detected.
“The result was a surprise,”said Antonino Lanza from the INAF–Catania Astrophysical Observatory, co-author of the study. “We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night.”
Watch a video below illustrating the rotation of Ceres and how reflected light from the bright spots within Occator crater are alternately blue- and red-shifted according to the motion relative to Earth.
First observed with Hubble in December 2003, Ceres’ curious bright spots were resolved by Dawn’s cameras to be a cluster of separate regions clustered inside the 60-mile (90-km) -wide Occator crater. Based on Dawn data they are composed of some type of highly-reflective materials like salt and ice, although the exact composition or method of formation isn’t yet known.
Since they are made of such volatile materials though, interaction with solar radiation is likely the cause of the observed daily brightening. As the deposits heat up during the course of the 4.5-hour Ceres daytime they may create hazes and plumes of reflective particles.
“It has been noted that the spots appear bright at dawn on Ceres while they seem to fade by dusk,” noted study lead author Paolo Molaro in the team’s paper. “That could mean that sunlight plays an important role, for instance by heating up ice just beneath the surface and causing it to blast off some kind of plume or other feature.”
Once day turns to night these hazes will re-freeze, depositing the particles back down to the surface—although never in exactly the same way. These slight differences in evaporation and condensation could explain the random variation in daily brightening observed with HARPS.
These findings have been published the journal Monthly Notices of the Royal Astronomical Society (full text on arXiv here.)
With NASA’s Dawn spacecraft set to enter its final and lowest orbit around the dwarf planet Ceres, spectral measurements are enabling researchers to gradually unravel the nature of the numerous mysterious and intriguing bright spots recently discovered and now conclude that briny mixtures of ice and salts apparently reside just beneath certain patches of the pockmarked surface and that “water is sublimating” from the surface of an “active crater”.
Indeed, excited scientists report that high resolution images and spectra from Dawn indicate that Ceres is an active world even today, according to a pair of newly published scientific papers in the journal Nature.
Ceres occupies a very ”unique niche” unlike any other world in our Solar System with “occasional water leakage on to the surface,” Dawn Principal Investigator Chris Russell told Universe Today.
Orbital measurements from the probes Framing camera reveal that the bright areas likely contain hydrated magnesium sulphates, a class of mineral salts found inside the brightest spot on Ceres, namely Occator crater – which are the salt-rich leftover residues from water evaporation.
The newly released results also show evidence of a diffuse haze of water vapor above Occator crater, which appears to be among the youngest features on Ceres, as well as at a second region at Oxo crater.
The Cerean haze is formed by the warming effects of sunlight shining on the hydrated salts inside the crater. The salts were exposed by past impacts of asteroids all across Ceres. The haze could be comprised of “condensed-ice or dust particles.”
“The Occator crater on the surface of dwarf planet Ceres is active: data from NASA’s Dawn mission indicate water sublimating from its center,” say Dawn researchers in a statement.
Video caption: Ceres Rotation and Occator Crater. Dwarf planet Ceres is shown in these false-color renderings, which highlight differences in surface materials. Images from NASA’s Dawn spacecraft were used to create a movie of Ceres rotating, followed by a flyover view of Occator Crater, home of Ceres’ brightest area. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
“Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles9, 10 may explain this haze,” write the authors in the Nature paper.
Occator is the brightest of more than 130 strikingly bright patches spread across the Texas-sized world, which ranks as the largest object in the main asteroid belt between Mars and Jupiter. It has an average diameter is 584 miles (940 kilometers).
NASA says Occator is a rather new impact crater, formed by an asteroid impact as recently as only 70 million years.
“The most plausible interpretation of our results is that there is a mixture of ice and salts under at least some parts of Ceres’ surface,” says lead study author Andreas Nathues of the Max Planck Institute for Solar System Research, Göttingen, Germany, in a statement.
“This material could be exposed by the impacts of medium-sized asteroids. The ice gradually evaporates until only salts and phyllosilicates are left.”
The mysterious bright spots inside Occator crater – looking somewhat like a pair of alien eyes – were only discovered earlier this year as NASA’s Dawn orbiter was on its final approach to Ceres.
Occator measures about 60 miles (90 kilometers) across and 2 miles (4 kilometers) deep. It also features a central pit “covered by this bright material, that measures about 6 miles (10 kilometers) wide and 0.3 miles (0.5 kilometers) deep. Dark streaks, possibly fractures, traverse the pit. Remnants of a central peak, which was up to 0.3 miles (0.5 kilometers) high, can also be seen,” say officials.
Prior to entering orbit on March 6, 2015, scientists speculated that Ceres might harbor a subsurface ocean of liquid water that could be hospitable to life.
Now with new data in hand, the presence of a large subsurface ocean of liquid water or water ice appears ever more likely.
“The global nature of Ceres’ bright spots suggests that this world has a subsurface layer that contains briny water-ice,” noted Nathues, who is also lead investigator of the Framing camera team.
The bright spots of Occator have captivated popular imaginations worldwide even as scientists struggled mightily, until recently, to explain what they really are.
Possible explanations ranging from frozen ices, salts and cryovolcanoes have been proposed for the past year as researchers sought to gather measurements explaining their elusive cause.
“We are currently probably seeing remnants of an evaporation process exhibiting different stages in different locations. Perhaps we are witnessing the last phase of a formerly more active period”, says Nathues.
To date, there has been no unambiguous detection of water ice on the surface of Ceres.
“Occasional water leakage on to the surface could leave salt there as the water would sublime,” Prof. Chris Russell, Dawn principal investigator told Universe Today recently in an exclusive.
“The big picture that is emerging is that Ceres fills a unique niche.”
“Ceres fills a unique niche between the cold icy bodies of the outer solar system, with their rock hard icy surfaces, and the water planets Mars and Earth that can support ice and water on their surfaces,” Russell, of the University of California, Los Angeles, told me.
On Oct. 23, Dawn began a seven-week-long dive that uses ion thruster #2 to reduce the spacecrafts vantage point from 915 miles (1,470 kilometers) at the High Altitude Mapping Orbit (HAMO) down to less than 235 miles (380 kilometers) above Ceres at the Low Altitude Mapping Orbit (LAMO).
Dawn is slated to arrive at LAMO by mid-December, just in time to begin delivering long awaited Christmas treats.
Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.
The asteroid Vesta was Dawn’s first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012.
The mission is expected to last until at least March 2016, and possibly longer, depending upon fuel reserves.
“It will end some time between March and December,” Dr. Marc Rayman, Dawn’s chief engineer and mission director based at NASA’s Jet Propulsion Laboratory, Pasadena, California, told Universe Today.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
No one’s 100% certain what WT1190F is — asteroid or rocket stage — but we are certain it will light up like a Roman candle when it re-enters Earth’s atmosphere around 6:20 Universal Time (12:20 a.m. CST) tomorrow morning Nov. 13. (…)Read the rest of Asteroid? Rocket Stage? Whatever it is, WT1190F Plunges to Earth Tonight (396 words) […]
Get ready for a man-made fireball. A object discovered by the Catalina Sky Survey on Oct 3rd temporarily designated WT1190F is predicted to impact the Earth about 60 miles (100 km) of the southern coast of Sri Lanka around 6:20 Universal Time (12:20 a.m CST) on November 13. The objects orbits Earth with a period of […]
Halloween fireballs, a Supermoon and now a near-Earth asteroid flyby. What a week! While 2015 TB145 won’t be visible in binoculars because of its relative faintness and glare from a nearby waning gibbous Moon, you should be able to see it in an 8-inch telescope or larger telescope without too much difficulty. Determined amateurs might even […]
Trick or treat! I think we’re definitely in for a treat. 2015 TB145 will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 12:05 p.m. CDT (17:05 UT). Estimated at 1,300 feet (400-meters) across, this Great Pumpkin of an asteroid will be big enough and close enough to […]