The dwarf planet Ceres, at 587 miles wide the largest object in the main asteroid belt between Mars and Jupiter, has a different surface composition than previously thought—and it took NASA and DLR’s Boeing 747-based SOFIA observatory to make the distinction. By observing Ceres in mid-infrared, only possible from high altitudes above infrared-absorbing water vapor, SOFIA found that Ceres is covered in silicates—pyroxenes—that likely came from impacts, the result of infalling material from elsewhere in the asteroid belt…the “dust” of asteroid collisions.
These findings show that Ceres is fundamentally different from the other carbonaceous C-type asteroids, among which it is grouped.
By observing Ceres in mid-infrared, we now know that its C-type appearance is really just a “camouflage,” a thin veneer formed from its local surroundings. It’s possible that Ceres really formed elsewhere in the Solar System and migrated to its current position billions of years ago.
These findings could not have been possible from ground-based observatories, and even NASA’s Dawn spacecraft currently in orbit around Ceres doesn’t have the mid-infrared capabilities of SOFIA.
“SOFIA, with its airborne location and sensitive FORCAST instrument, is the only observatory, currently operating or planned, that can make these kind of observations,” said Franck Marchis, planetary astronomer at the SETI Institute and co-author of the study. “These and future mid-infrared observations are key to understanding the true nature and history of the asteroids.
“The bottom line is that seeing is not believing when it comes to asteroids,” Marchis said. “We shouldn’t judge these objects by their covers, as it were.”