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Old 5th August 2009, 11:42 PM   #213
Reality Check
Penultimate Amazing
Join Date: Mar 2008
Location: New Zealand
Posts: 26,873
Exclamation Comets may not have the composition of asteriods

Hi Sol88, I noticed that in the last post I assumed that the electric comet idea has comets with the same composition as asteriods. You have not disagreed with this so far. So here is the science (not as clear cut as the different densities of comets and asteroids).

Physical composition of asteroids
The physical composition of asteroids is varied and in most cases poorly understood. Ceres appears to be composed of a rocky core covered by an icy mantle, whereas Vesta is thought to have a nickel-iron core, olivine mantle, and basaltic crust,[15] and 10 Hygiea appears to have a primitive composition of undifferentiated carbonaceous chondrite. Many, perhaps most, of the smaller asteroids are piles of rubble held together loosely by gravity.
Meteorites also suggest that "Asteroids are believed to contain traces of amino-acids and other organic compounds".

Physical composition of comet nuclei
They are composed of rock, dust, water ice, and frozen gases such as carbon monoxide, carbon dioxide, methane and ammonia.[9]
They are often popularly described as "dirty snowballs", though recent observations have revealed dry dusty or rocky surfaces, suggesting that the ices are hidden beneath the crust (see Debate over comet composition). Comets also contain a variety of organic compounds; in addition to the gases already mentioned, these may include methanol, hydrogen cyanide, formaldehyde, ethanol and ethane, and perhaps more complex molecules such as long-chain hydrocarbons and amino acids.[10][11][12]
This suggests that the composition of comets and asteroids differ in that comets have the addition of frozen gases while asteroids generally do not have frozen gases (but may have icy crusts).
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