Ceres

Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/Justin Cowart

The Astriods Belts Only Dwarf Planet

By Beryl Keaughran

As most people know the largest Asteroid Belt in our solar system orbits the sun between Mars and Jupiter, it is sometimes called the Main Belt. Most think it’s just full of odd-shaped rocks swirling around that were created in the forming of our solar system. And they are right. But there are some interesting rocks inside the Belt.

Namely one asteroid called Ceres, the largest Asteroid in the Belt making up a total of 1/3 the mass of the belt. It is classed as a dwarf planet, the only one in the Main belt and the only dwarf planet continuously inside of Neptune’s orbit.

Ceres was discovered in 1801 at the Palermo Astronomical Observatory in Sicily by Giuseppe Piazzi but the existence of a planet between Mars and Jupiter was hypothesized as far back as 1506 by Johannes Kepler. It was only classed as an asteroid when first discovered but there has always been some discussion around the classification of small planets or large asteroids.

When Pluto was demoted in 2005 the debate over Ceres started again and in 2006 it was brought into the category of Dwarf Planet. Cere’s radius of 296 miles and the diameter of 588 miles were not the dimensions that were recognized as a planet, so it stuck in the category of Dwarf Planet. Ceres is something we call a protoplanet, the only one remaining in the inner solar system. It wanted to become a planet but Jupiter’s very strong influence, which sometimes causes meteors from the Belt to leave and hurtle out into space, stopped this from happening. It likely started its formation between Jupiter and Saturn and was then flung into the Main Belt where it now stays.

Until 2018 Ceres had a secret. Astronomers had seen bright white spots on the floor of the largest crater called Occator which they thought was ice. NASA sent an unmanned spacecraft, called Dawn, to orbit the Asteroid travelling just 130 kms above the surface to collect and send back data. What they discovered was amazing. The white spots were not ice but salt crystals.

Whatever impacted Ceres some 20 million years ago had hit so hard that it cracked the surface floor of the crater. Through these cracks, bubbling to the surface was brine coming from a huge intensive reservoir of saltwater from inside the asteroid, when the water evaporates it leaves the salt crystals.

The reservoir is thought to be 100 kms long and wide. Ceres is now called an Ocean World. Although it is unlikely that life has ever or would ever be possible on Ceres it is always nice to know that our closest Dwarf Planet is not just an odd-shaped rock but has a bit more of an interesting story.