From UPSC perspective, the following things are important :
Prelims level : Ceres and other dwarf planets
Mains level : Not Much
The dwarf planet Ceres, which lies in the asteroid belt between Mars and Jupiter now, has the status of an “ocean world”.
Note various dwarf planets and the criteria making a planet dwarf, as mentioned in the B2b section.
- The dwarf planet was first spotted by Giuseppe Piazzi in 1801, who assumed that Ceres was the missing planet between Mars and Jupiter.
- It was classified as a dwarf planet in 2006 and is the first dwarf planet to be orbited by a spacecraft.
- In 2015, NASA’s Dawn reached it to study its surface, composition and history.
What does it mean to be an “ocean world”?
- With a crust that mixes ice, salts, rock-forming minerals and other materials, Ceres looks to be a remnant “ocean world,” wearing the chemistry of its Old Ocean and records of the interaction on its surface.
- The observations from Dawn suggest the presence of briny liquid (saltwater) water under Ceres’s surface.
- Scientists have determined that Ceres has a brine reservoir located about 40 km deep and which is hundreds of miles wide, making the dwarf planet, “water-rich”.
Why do researchers study Ceres?
- Scientists are interested in this dwarf planet because it hosts the possibility of having water, something that many other planets do not have.
- Therefore, scientists look for signs of life on Ceres, a possibility that has also maintained scientists’ interest in the planet Mars, whose atmosphere was once warm enough to allow water to flow through it.
- Another reason why scientists are interested in that studying it can give insights about the formation of the Solar System since it is considered to be a fossil from that time.
Back2Basics: Dwarf Planets
- As of today, there are officially five dwarf planets in our Solar System.
- The most famous is Pluto, downgraded from the status of a planet in 2006.
- The other four, in order of size, are Eris, Makemake, Haumea and Ceres. The sixth claimant for a dwarf planet is Hygiea, which so far has been taken to be an asteroid.
- These four criteria are – that the body orbits around the Sun, it is not a moon, has not cleared the neighbourhood around its orbit and has enough mass for its gravity to pull it into a roughly spherical shape.