Drew Rae answered on 17 Jun 2011:
Hi Dylan. Good question! The biggest asteroid is Ceres – so big that in fact it is now classed as a Dwarf planet. When it was discovered they thought it was a planet, because their current understanding said there should be a planet between Mars and Jupiter. Ceres has a rocky core and an icy surface – just like a small planet.
They found another three big asteroids soon after Ceres – they all have names (Pallas, Juno and Vesta) – and it was years before they found another one. It wasn’t until they started taking very long exposure pictures of the sky that they realised that there was a whole asteroid belt.
Julia Griffen answered on 19 Jun 2011:
Fraid I cant… I dont know alot about space 🙁 Sara’s prob your girl for this one!
Amy MacQueen answered on 19 Jun 2011:
Hi Dylan – I have a similar answer to Julia…I don’t know much about them so I would have to do a google search to find you reliable information. But you can probably do that quicker than I can! I would be interested to see what Sara knows though!! 🙂
Sara Imari Walker answered on 20 Jun 2011:
Hey dylanho!! Drew’s provided some pretty cool facts here! Asteroids are pretty neat, and Drew’s named some of the coolest. Ceres, Pallas, Juno and Vesta are all part of the asteroid belt – a ring of several million such rocket objects that orbits between Mars and Jupiter. Drew’s named some of the biggest. In fact, they are so big that when these objects were first discovered in the 1800s people thought they were planets! They started naming them as such, but it quickly became overwhelming and asteroids were demoted from planetary status when it was realized they were a new class of object. Although some are so large as to be nearly circular due to their own gravity and have been recently reclassified as dwarf planets along with Pluto (Ceres falls in this category).
It might be pretty unique that our solar system has an asteroid belt. Most believe it is because of the huge mass of Jupiter that an asteroid belt formed rather than a planet. Because of the pull of Jupiter against that of the Sun, it is believed that a planet located at the orbit of the asteroid belt would be unstable, so instead we see a bunch of smaller objects. Asteroids, like comets, are pretty interesting because they may have a lot of water and organics in them (both important for life!). The primary compositions of asteroids can very significantly from being mostly composed of carbon, to being pretty stony or metallic. Some have even proposed mining certain asteroids for precious metals!
Something else cool is the recent Hayabusa spacecraft sent by Japan to travel to an asteroid, collect samples, and return them to Earth for studies. The spacecraft returned after a successful mission in 2010.
Also, the too moon of Mars Phobos and Deimos are both believed to be captured asteroids.
Basically, asteroids are pretty neat!