Free Form: Dwarf Planets and Ceres

A dwarf planet is an object that is neither a planet nor a satellite, meaning that it is in orbit around the Sun, is massive enough to be in Hydrostatic equilibrium under its own gravity, but has not "cleared the neighborhood" around its orbit. A cleared neighborhood simply means that the object is the gravitationally dominant object in its orbit zone, other than its own satellites. So a dwarf planet is just like a planet except that there is at least another body of comparable mass occupying the same orbit zone.

Image of Ceres taken from Dawn
Image Credit:
http://upload.wikimedia.org/wikipedia/commons/b/be/PIA18920-Ceres-DwarfPlanet-20150219.jpg

The dwarf planet, Ceres, is the largest object in the asteroid belt between Mars and Jupiter. It has a diameter of 950 km and a mass of about \(9.43\times 10^{20}\) kg. As a size comparison, you can see how small Ceres is compared to the Earth.

Size comparison of Ceres to Earth
Image Credit: http://space-facts.com/ceres/

Interestingly, Ceres has plumes of water vapor shooting from its surface, causing the dwarf planet to lose 6 kg of its mass per second. About 25% of its mass is ice water. Ceres is one of the most observed dwarf planets in addition to Pluto. Only a month ago, the spacecraft, Dawn, entered orbit around Ceres. The Dawn is the first spacecraft to land on a dwarf planet and the first to orbit two extraterrestrial objects. The purpose of the mission is to gather data on asteroids and their dimensions, mass, structure, compositions, etc. This information would help astronomers understand more about water on asteroids and the thermal history on asteroids.

The spacecraft, Dawn
Image Credit: http://space-facts.com/dawn-spacecraft/

Recent pictures from Dawn revealed a color map of the surface of Ceres, indicating diversity on the surface of the dwarf planet, which could be evidence that Ceres had been more active in the past. The difference in colors means that different parts of the surface resulted in different materials from the various processes. Furthermore, there are two bright spots on the surface of the dwarf planet. What exactly these spots are is unknown since they occur in areas of hot temperature as well as cooler temperature. As the spacecraft nears Ceres, we will be able to get a closer look at these spots.

Bright spot on the surface of Ceres
Image Credit: http://space-facts.com/ceres-pictures/

Citations:
http://en.wikipedia.org/wiki/Dwarf_planet
http://en.wikipedia.org/wiki/Clearing_the_neighbourhood
http://space-facts.com/ceres/
http://space-facts.com/ceres-pictures/
http://space-facts.com/dawn-spacecraft/
http://www.nasa.gov/jpl/dawns-ceres-color-map-reveals-surface-diversity/