NASA’s Dawn spacecraft has just returned its first photo of the dwarf planet Ceres, taken from 1.2 million kilometers away.
Dawn spacecraft captured this image as part of a calibration of its science camera: the dwarf planet Ceres is the bright spot in the center of the image; a cropped, magnified view of Ceres appears in the inset image at lower left. Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA.
Discovered on January 1, 1801 by the Italian astronomer Giuseppe Piazzi, Ceres is the largest body in the main asteroid belt.
It is about 950 kilometers in diameter and has an apparent magnitude that can range from 6.7 to 9.3.
Ceres was the largest known asteroid in the asteroid belt until 2006. But in 2006, the International Astronomical Union formed a new class of objects known as dwarf planets. By definition a dwarf planet is spherical and travels in an orbit around the Sun, and Ceres fits this definition perfectly.
Planetary scientists believe that water ice may be buried under Ceres’ crust because its density is less than that of the Earth’s crust, and because the dust-covered surface bears spectral evidence of water-bearing minerals. Ceres could even boast frost-covered polar caps.
Scientists estimate that if the dwarf planet were composed of 25 percent water, it may have more water than all the fresh water on our planet.
Ceres is one of the targets of NASA’s Dawn space probe. Since launching in 2007, the spacecraft has already visited Vesta, a giant protoplanet currently located 168 million kilometers away from Ceres. During its 14 months in orbit around Vesta, it delivered unprecedented scientific insights, including images of its cratered surface and important clues about its geological history.
This is an artist’s impression of the dwarf planet Ceres. Image credit: NASA / JPL-Caltech.
The new image of Ceres was captured as part of a final calibration of the science camera before Dawn’s arrival at the dwarf planet.
To accomplish this, the camera needed to take pictures of a target that appears just a few pixels across. On December 1, 2014, Ceres was about nine pixels in diameter, nearly perfect for this calibration.
Dawn will be captured into Ceres’ orbit in March, marking the first visit to a dwarf planet by a spacecraft.
“Now, finally, we have a spacecraft on the verge of unveiling this mysterious, alien world. Soon it will reveal myriad secrets Ceres has held since the dawn of the Solar System,” said Dr Marc Rayman from NASA’s Jet Propulsion Laboratory in Pasadena, director of the Dawn mission.
To date, the best images of Ceres scientists have so far were made by NASA’s Hubble Space Telescope.
