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A Ceres of Planets

A giant asteroid named Ceres is being considered for initiation in the most exclusive club in the Solar System: the Planets.

If your astronomy’s a little rusty, here’s a refresher: there’s an asteroid belt in between Mars and Jupiter – in essence, a bunch of rocks. The predominant theory for the asteroid belt is when the inner planets were forming, there were some pieces of matter on the outskirts that didn’t have enough gravity to pull them into a larger planet – thus the asteroid belt.

Composition-wise, Ceres has been called an “embryonic planet” meaning it’s still in a form similar to where Earth was 4 billion years ago. What’s cool about Ceres is its mantle (the part surrounding the core) may hold more fresh water-made ice than we have on Earth. I can just picture Evian and Crystal Geyser harvesting the water from Ceres in the next milennium.

Why a planet? Because it’s big enough to hold its own in relation to the Sun’s gravitational pull. Anything with a mass greater than 500,000,000,000,000,000,000 kilograms and a diameter over 800 kilometers (497 miles) will now be a member of the club. Ceres is the biggest of over 10,000 rocks and it holds about 25 percent of the mass of all of the asteroids comprising the belt (which in total is less than the Moon’s mass).

Ceres is roughly 1/14th the size of Pluto, but by the new planetary definitions, it would make the cut. Ceres has a diameter roughly the equivalent of Texas. As if Texans needed this to boost their egos – now they can claim not only to be big enough to be their own country, but they can claim to be big enough to be their own planet.

2500 astronomers who comprise the International Astronomical Union will vote on August 24th as to whether Ceres gets admitted into the club. If so, it will be one of twelve members.


  1. >Think of all the marketing opportunities for selling naming rights to the new planets and “plutons”: planet Coke, PacBell (er, AT&T) pluton… Perhaps we could use the funds to build a real space station.

  2. >Ugh, don’t even go there…They’re prepping the Atlantis crew for another space station completion mission, according to the NASA site. There’s a mission blog too starting once the countdown begins.