Source: http://www.bbc.com/earth/story/20150831-...

When it comes to underdog planets, Ceres might be at the top of the list. Sure, you've probably heard about Pluto's demotion to dwarf planet. But before Pluto, there was Ceres. 

Ceres also once enjoyed full membership in the solar system's planetary fraternity. When astronomers discovered it in 1801, it was the only object known between Mars and Jupiter. Its story echoes Pluto's. After astronomers found more bodies in similar orbits - objects that became part of what's now known as the asteroid belt - they reclassified Ceres as an asteroid.

For instance, Ceres is one of the most watery worlds in the solar system, with water comprising about 15 percent of its mass and a third of its volume, according to the latest estimates. Most of the water is locked up in ice, but scientists think that deep in its interior, some of it may be liquid. As water is necessary for life, this has implications for habitability. It's not just any asteroid, though. It's still the biggest one there is, accounting for about a third of all the mass in the asteroid belt. Ceres is big enough for gravity to have made it round, which qualifies it as a dwarf planet as well. Despite this humble status, Ceres is proving to be way more interesting than just another space rock.

That's not to say Ceres is home to aliens but such a world contains vital clues about the origins of life - on Earth and beyond.