Chuck Bednar for redOrbit.com – @BednarChuck
A bright spot previously detected on the dwarf planet Ceres appears to have a somewhat dimmer companion, and NASA remain unable to explain exactly what these unusual lights are.
According to Mashable, the two spots were detected by the US space agency’s Dawn spacecraft as it approaches Ceres en route to a March 6 rendezvous with the dwarf planet. Images captured by the vehicle from further away showed a single light, but now a second has appeared.
An image taken by Dawn from a distance of less than 29,000 miles on February 19 clearly shows that there are two bright areas located in the same basin on the dwarf planet’s surface. The two lights are reflecting approximately 40 percent of the light that is hitting them, the website added.
[STORY: Dawn spacecraft captures sharper image of Ceres]
“Ceres’ bright spot can now be seen to have a companion of lesser brightness, but apparently in the same basin,” Chris Russell, principal investigator for the Dawn mission, said in a statement. “This may be pointing to a volcano-like origin of the spots, but we will have to wait for better resolution before we can make such geologic interpretations.”
“The brightest spot continues to be too small to resolve with our camera, but despite its size it is brighter than anything else on Ceres,” added Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research, Gottingen, Germany. “This is truly unexpected and still a mystery to us.”
Ice, ice, baby
One possible explanation is that the bright spots are ice, since scientists had previously detected water vapor coming from the surface of Ceres. While ice would most likely reflect more than 40 percent of the light that hit it, the resolution limits of Dawn’s imaging equipment at its current distance may make it appear otherwise.
If it’s not ice or volcanic activity, the bright areas could be patches of salt, Mashable noted. The Dawn researchers will have to wait until the spacecraft approaches Ceres next week, and collects more photographs of the dwarf planet over the next 16 months, the website added.
[STORY: Mysterious white spot seen on Ceres]
In an email sent to NBC News, Russell said that icy surfaces “would not last on Ceres… but if there were ice below the surface it might be occasionally exposed a little bit.” Salt, on the other hand, “would be more reflective than the general claylike material we think covers much of the surface. So there is a range of possibilities.”
Galactic hot spot
While volcanic activity is possible in some form, he and his colleagues have eliminated the possibility that the lights are spots that are made up of lava like those found on Jupiter’s moon Io. “That would make a hot spot,” Russell said. “We would have noticed a hot spot by now.”
Ceres, which is the largest object in the asteroid belt between Mars and Jupiter, is the second destination for Dawn, which had previously visited the giant asteroid Vesta in 2011 and 2012. During its stay there, the spacecraft collected over 30,000 images and several measurements of the object, revealing new information about its composition and geology.
[STORY: Could NASA’s Europa mission search for alien life?]
With an average diameter of 590 miles (950 kilometers), Ceres is far larger than Vesta, which has an average diameter of just 326 miles (525 kilometers). Ceres contains roughly one-third the mass of the entire asteroid belt and is the only dwarf planet in the inner Solar System. It was also the first asteroid ever discovered (in January 1801 by Italian astronomer Giuseppe Piazzi).
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