Home > astronomy > I'm embarrassed I've never heard of this before

I'm embarrassed I've never heard of this before

Along with the nine (sorry, eight) planets in the solar system, there are these things called dwarf planets. They’re like normal planets, but smaller, and everything they do is funnier because they’re dwarfs. Also, they orbit the sun, but aren’t able to clear the neighborhood of its orbit, meaning that are no other bodies in its orbital path.

My favorite of these dwarf planets (that is, favorite for now, because it’s the first one I’ve heard about) is called Ceres. It’s actually the smallest of the dwarf planets and exists within the asteroid belt between Mars and Jupiter. Despite being the smallest of the dwarf planets, it has 1/3 of the mass of all the asteroids in the solar system, which is pretty amazing when you think about it, and even with all that mass it’s still only 4% the mass of the moon.

Here’s the really cool part. It’s theorized that underneath the crust of Ceres, there’s an icy mantle 100 km thick. This mantle would contain 200 million cubic kilometers of water. This is more than all the fresh water on Earth. In between the crust and this ice mantle, there might also be layer of liquid  water. If there were actually a layer of liquid water it would be highly volatile and saturated with salts, ammonia and other chemicals that would act as antifreeze.

When the definition of planet was reclassified in aught six, there was a debate on whether Ceres and a number of other dwarf planets would become full fledged planets. One of the possible classifications would be if the object had enough mass and gravity to take on a spherical shape and orbited the sun instead of another planet or object it would be a planet. However, it was decided that a third stipulation be added, which was that the object’s orbital be cleared of any other objects. This is the rule that caused Pluto to be declassified as a planet and kept Ceres from becoming one.

I’m wondering if Ceres won’t eventually clear her orbit. It must be slamming into asteroids all the time. Each impact changing adding to its mass (or maybe subtracting) and ever so slightly changing the velocity and orbit. You’d think that on a long enough timeline it would eventually gobble up all the asteroids, or at least gobble them up until it runs into something too big for its britches and it becomes a dwarf of a dwarf planet.

Now, if you’ll excuse me, I’m going to unload a huge wad of history on y’all.

Ceres was discovered in 1801 by some crusty old game named Giuseppe Piazzi. That’s pretty impressive when you think about it. This is an object that’s only about 1,000 km in diameter and it’s twice as far away from us as we are from the sun. Nobody but a crusty old guy would have the tenacity to discover something like that. It’s like finding a needle in a haystack, when you’re not even looking for the needle, and it was done over 200 years ago. Before reporting his findings Giuseppe watched Ceres’s movement for about a month to try and determine what it was, then illness took him away from his work. However, by the time other astronomers could take a look for Ceres on their own, it had changed position and was being hidden by the Sun’s glare. The astronomers of the time had to discover it all over again. However, a crusty young guy, Carl Friedrich Gauss who was only 24 at the time, figured out an equation to find it’s approximate location. Since so little was known about Ceres at the time, the equation had a number of unknown quantities and only one known quantitiy, the orbit of the Earth. Through much trial and error and plugging and chugging, and a maddening amount of variable paperwork, they got a rough estimate of where Ceres should be. After that, it didn’t take much searching to find it.

Coincidentally enough, the first observation of Ceres happened on January 1st 1801, and the first time it was rediscovered was Dec 31st 1801. The first day of the year and the last day of the year.

As a complete aside, I just want to plug something cool I found while looking stuff up on ceres. Wikipedia is apparently in the book business now.


They’ve started compiling similar articles together and making them into reference books. You can download them for free, or you can have wikipedia print you a copy for a nominal fee. I just downloaded one on the solar system and it’s pretty impressive. It’s got a table of contents, index, graphs, charts, pretty pictures, and, that bane of all research students, numerous bibliographies. There’s nearly 600 pages and 60 MB of stuff on the solar system in this “book” which is all searchable since it’s in PDF format. I’ll probably never read a lick of it, but I still find it very impressive and a neat thing to download for free. Plus they’ve got a buttload of other subjects to peruse through. Give ’em a look-see.

Categories: astronomy Tags: , ,
  1. fleabaggz
    July 17, 2010 at 1:53 pm

    I wonder if mining for fresh water on other planets would be something that could happen in the future. Well, antifreeze.
    Having a cold inner layer of planet completely throws whatever kiddie encyclopedia knowledge of planets that I have.

    • DJ
      July 17, 2010 at 3:44 pm

      Given a long enough timeline anything’s possible. We could start on the Moon, they apparently have a ton of it there.


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