The legend of the white spots on Ceres continues to grow as the mystery of what they are intensifies.
New images of Ceres, taken by NASA’s Dawn spacecraft, offer a closer view of the spots, but still no answer to the mystery.
The spots are not the only features in the Ceres system that is intriguing scientists. For example, the sphere also includes central pits in large craters that are much more common on its surface than on icy moons in the outer solar system.
Dawn has been studying Ceres in detail from its second mapping orbit, which is 2,700 miles (4,400 kilometers) above the body. A new view of the spots, located in a crater about 55 miles (90 kilometers) wide, shows more small spots in the crater than were previously visible.
From its vantage point now Dawn has snapped pictures of at least eight spots next to the largest bright areas. Scientists believe that the area is about 6 miles (9 kilometers) wide. It is apparent that a highly reflective material is responsible for the spots, which could be ice and salt or other substances.
Dawn is carrying a visible and infrared mapping spectrometer that is designed to identify specific minerals present on Ceres by observing how light is reflected. Each mineral reflects the range of visible and infrared-light wavelengths in a unique way. This signature helps scientists determine the components on Ceres. So, as the spacecraft gets close it is expected to send back more images and data that should solve the mystery of the bright spots.
The latest images also show a mountain with steep slopes protruding about 3 miles (5 kilometers) from a relatively smooth area of the sphere’s surface. There are also numerous craters with central peaks and there is evidence of past activity on the surface including flows, landslides, and collapsed geographic structures. It appears that Ceres shows more remnants of activity than Vesta, which Dawn studied intensely for 14 months in 2011 and 2012 on its way to Ceres.
Dawn is the first spacecraft to flyby a dwarf planet, and the first to orbit two distinct targets in our solar system. It arrived at Ceres, the largest object in the main asteroid belt between Mars and Jupiter, on March 6, 2015.
The craft will remain in its current altitude above the planet until June 30 and will continue to snap images and perform spectra readings as it orbits Ceres. It will then move into a new orbit about 900 miles (1,450 kilometers) above the surface starting in early August.
The Jet Propulsion Laboratory is managing the project for NASA. UCLA is responsible for overall Dawn mission science. Orbital ATK, Dulles, Virginia, designed and built the craft. The German Aerospace Center, Max Planck Institute for Solar System Research, the Italian Space Agency, and the Italian National Astrophysical Institute are international partners.
Do you have an idea of what those bright spots are on Ceres? You can vote at the JPL/NASA/Dawn website.