A dwarf planet is an object in orbit around the Sun which is large enough to be spherical but not large enough to have cleared its orbit of debris. Pluto is the most famous example of a dwarf planet, it had its designation changed in 2006 after astronomers began to find other objects of a comparable size in the Kuiper Belt region of the outer Solar System.
Ceres is the closest dwarf planet to the Sun, located in the asteroid belt between Mars and Jupiter. It was discovered by Giuseppe Piazzi in 1801 but we haven't been able to study it in detail until now.
Dawn has already found that Ceres has two small bright patches on its surface that are currently unexplained. Astronomers working on the mission hope to learn more about the origin of the bright spots and about the structure of Ceres over the coming months.
|An image of Ceres taken by Dawn on its approach to the dwarf planet. |
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA