That’s no moon…

While my equipment is thermally equillibriating, I actually have time for a bite sized blog entry.* And appropriately, I’ve been meaning to write a little about a bite sized “planet”…

Well… I say planet. This is Ceres, the empress of the Asteroids. Discovered in 1801 by an italian catholic priest named Giuseppe Piazzi, it was considered the 8th planet for around half a century. At least Pluto went straight to being a “dwarf planet”. Poor Ceres was demoted to being simply an asteroid for a long time. Any school kid with an interest in space will know about Pluto. But, at least in my school, none of the books even bothered to mention tiny Ceres. The whole debacle surrounding Pluto actually caused the IAU to briefly consider promoting Ceres back to the status of planet, before the dwarf planet classification was devised.

Ceres is certainly diminutive. Substantially smaller than Earth’s moon, it could easily be captured by an Earth-sized world as a moon. While Ceres may be the smallest of the dwarf planets, it still dominates the asteroid belt, making up around one third of the belt’s total mass. It’s massive enough to be roughly spherical, and is thought to be made up of a mixture of rock and water ice, not too dissimilar to some of Jupiter’s moons. The trouble is that Ceres escaped the attention of so many people for so long, that we’ve never once been there. Its surface shows unusual features, dark spots and bright spots. There’s clear detail. Perhaps most interestingly, there’s a good chance that Ceres is actually a relic of a bygone age. Many suspect that Ceres is actually a surviving protoplanet. Never merging with other objects to form a full sized planet, escaping the cataclysms that created the worlds we know so well. In a sense, Ceres could be a planetary fossil…

*My ethic at the moment is to try and write more 10 minute bite sized blog entries. If I don’t push myself to write full sized entries every time, maybe I’ll write more often…

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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6 Responses to That’s no moon…

  1. Pingback: Asteroid spotting | Supernova Condensate

  2. 6_bleen_7 says:

    Interesting—thanks for the info!

  3. invaderxan says:

    Aww, why thank you! :)

  4. invaderxan says:

    Oh, I don’t know. I’ve always considered dwarf planets to still be planets, in the same way dwarf stars are still stars…
    (I direct you towards a whimsical blog entry I wrote some years ago, now!)

  5. Even your bite sized entries are worth reading :)

  6. 6_bleen_7 says:

    According to Wikipedia, Juno has been ruled out as a dwarf planet, and Pallas and Vesta are under consideration. Is there an upper limit to out-of-roundness beyond which a body can’t be a dwarf planet?

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