Meteorites

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• Meteor: what you see in the sky
• Meteorite: what hits the ground
• Meteoroid: what's up in space
• Fall: a meteor(ite) seen hitting the Earth
• Find: a meteorite found on the ground, but no fall seen.

• Stones (95%): made of rocky material
• Ordinary Chondrites (81%): chondrules made up of small spherical inclusions, molten-then-cooled material -- probably from impacts.
• Carbonaceous Chondrites (5%): low temperature carbon-rich condensates, probably from outer solar system.
• Achondtrites (9%): no chondrules.
• Irons (4%): made of nickle/iron
• Stony-Irons (1%): mix of stone and nickle/iron

Radioactive dating puts ages of most meteorites at around 4.5-4.6 billion years -- the beginning of the solar system. Meteorites are unprocessed samples of the conditions in the forming solar system.

Widmanstatten Patterns: crystalline structures in iron meteorities. Patterns indicate cooling times - big crystals mean longer cooling times. They tell us something about the sizes of parent bodies for meteorites.

Some meteorites show isotopic anomalies: ratios of atomic isotopes unlike that of the Earth. The isotopic ratios are more like what is expected from nuclear reactions inside a supernova -- an exploding star. Did a nearby supernova occur when the solar system was forming -- or even trigger the formation?

Carbonaceous Chondrites contain organic material, including amino acids. Amino acids can bond to form proteins -- the beginnings of life. Could CC's have brought the beginning ingredients of life to the planets?

Are we all extraterrestrials, Mulder?