We STILL Don't Know What Those Bright Blobs on Ceres Are
Although NASA's Dawn mission is now carrying out its second mapping orbit of dwarf planet Ceres we're still none the wiser as to what those weird bright patches are.
Although NASA's Dawn mission is now carrying out its second mapping orbit of dwarf planet Ceres, beaming back the highest resolution images of the small world's surface to date, we're still none the wiser as to what those weird bright patches are.
"The bright spots in this configuration make Ceres unique from anything we've seen before in the solar system," said Chris Russell, principal investigator for the mission at the University of California, Los Angeles. "The science team is working to understand their source."
The blobs, which quickly shot to the headlines shortly before Dawn arrived in Ceres orbit in March, have kept their true nature secret. Although planetary physicists have some ideas as to what they may be, these white patches are becoming quite a mystery.
"Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt," added Russell in Wednesday's NASA news release. "With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon."
Although their nature is not currently known, these newest observations - from 2,700 miles (4,400 kilometers) above Ceres - are among the first from the second mapping orbit. The mission will remain at this altitude until June 28, when it will drop even closer to the dwarf planet. By early August, Dawn will be taking observations only 900 miles (1,450 kilometers) from the surface.
From this high-resolution look into the 55-mile (90-kilometer)-wide crater containing the bright patches, it is becoming clear that rather than being two amorphous blobs, there is some fine-scale structure - many individual white patches around a central cluster in two locations. And so far, without knowledge as to what they are, explanations for this fine-scale structure will not be forthcoming for some time.
But help is at hand; Dawn's visible and infrared mapping spectrometer (VIR) will be used to gauge the bright patches' temperature, which may prove critical to unraveling this enduring Cererian conundrum.
The brightest spots on dwarf planet Ceres are seen in this image taken by NASA's Dawn spacecraft on June 6, 2015.
The term "dwarf planet" wasn't defined until the infamous International Astronomical Union (IAU) vote in 2006, but this year, 9 years later, we are beginning to get our first ever close-up views of two of our solar system's most famous dwarf planets: Pluto and Ceres.
Currently spiraling in on Ceres, the innermost dwarf planet inhabiting the asteroid belt between the orbits of Mars and Jupiter, NASA's Dawn spacecraft is slowly revealing a cratered and complex world, details of which that have so far eluded even Hubble's powerful vision. Dawn is scheduled to make final orbital insertion around Ceres in March 2015 where it is destined to remain after its fuel runs out as a permanent human-made satellite of Ceres. A comparison image of the Hubble and Dawn views of Ceres is shown above.
But Dawn is just the first dwarf planet encounter of 2015. In July, NASA's New Horizons mission will flyby Pluto and its system of moons, exploring the mysterious Kuiper Belt. Between Hubble's blurry observations of Ceres and Pluto and this year's NASA encounters, many artists' impressions of these enigmatic worlds have guessed at what lies in store for our robotic explorers. But how do they measure up now we are beginning to see Ceres' and Pluto's surfaces?
This artist's impression of Ceres shows NASA's Dawn spacecraft in orbit around the dwarf planet. As opposed to an ice encrusted world, this visualization shows a cratered, moon-like surface.
Again with Dawn in view, this artist's impression shows an active Ceres complete with water vapor escaping from a possible sub-surface ocean. Water vapor was detected in the vicinity of Ceres by Hubble, so Dawn will be on the look-out for any trace of geysers venting water.
As seen by Hubble from afar, curious white patches and possible variations in Ceres' surface composition can be seen. However, any detail in these images have so far prevented planetary scientists from fully understanding the dwarf planet's true nature.
But now, as Dawn fast approaches orbital insertion, we're being treated to a bounty of data that shows a possibly ancient, rocky surface. Those curious white patches originally spied by Hubble are also snapping into view -- but what are they? Theories abound, but they may be tentative signs of subsurface water escaping to space and freezing on the surface. These are all signs of cryovolcanism, a dynamic that may dominate dwarf planet surface morphology.
From afar, NASA's Dawn mission is able to watch Ceres rotate, as this series of observations on Feb. 4 shows.
As Dawn gets up-close and personal with Ceres, the drama in the outer solar system is only just beginning to unfold. After 9 years of flying toward Pluto, NASA's New Horizons mission has begun approach preparations for its flyby in July.
From ground-based and Hubble observations, there at tantalizing clues that this frozen world has a surprisingly dynamic surface with a thin atmosphere that changes during Pluto's 248 year orbit around the sun. In this artist's impression of New Horizons flying over Pluto, an atmosphere has been included with cryovolcanos -- the latter of which planetary scientists hope to confirm in July.
Pluto has a system of known moons, the largest of which, Charon, may be considered to be Pluto's binary partner. As Charon orbits Pluto, its powerful gravitational field tugs the dwarf planet off center, a dynamic that New Horizons has observed as it approaches.
This artist's conception shows Pluto's moon Charon eclipsing the dwarf planet. Twice every orbit around the sun, each world eclipses the other.
When Hubble spies on Pluto, it can see the different shades of the dwarf planet's surface rotate. As shown here in these blotchy images, little detail is obvious, but large regions with differing albedo (reflectiveness) may reveal huge craters, vast plains or mountains. But until New Horizons gets close, these regions will remain a mystery.
In this digital illustration rendered from 3-D NASA data of Pluto, an attempt has been made at matching observations with possible surface features.
In July 2014, NASA's New Horizons looked ahead and spied its ultimate goal: Pluto and Charon. Although tiny pinpricks of light, the pair can be seen orbiting one another in a binary dance that shifts Pluto off center. Both masses actually orbit an invisible point in space, above Pluto's surface, known as the Pluto-Charon barycenter. These observations have increased calls for Pluto to be redefined (yet again) as a 'binary planet.'
Having spotted Charon months ago, New Horizons is now beginning to see Pluto's wider family of moons pop into view. Shown here are moons Nix (yellow diamond) and Hydra (orange diamond).
Once NASA's New Horizons mission careens through the Pluto-Charon system, assuming it doesn't hit any debris on its way through, its mission in the Kuiper Belt has only just begun. Hubble is currently being used to identify possible icy targets
the spacecraft's Pluto encounter. Shown here is an artist's impression of another dwarf planet, Eris, that was discovered in 2005. Originally thought to be the
planet of the solar system, its discovery led to the IAU's decision to reclassify these small worlds as dwarf planets, demoting Pluto in the process, leaving us with 8 planets. But as we approach Pluto and begin to understand Ceres, just because they are dwarf planets doesn't mean they're not rich and dynamic places to explore. Our voyage of dwarf planet discovery has only just begun and regardless of our need to classify celestial objects, Pluto and Ceres hold some fascinating clues to planetary formation and solar system evolution.
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