Zoom Astronomy Meteoroids, Meteors, and Meteorites

METEORITES

METEORITES FROM MARS Many meteorites from Mars have landed on Earth, one with a suspected microbial fossil.

CHONDRITIC METEOR Chondritic meteors are stony meteors with chondrules, tiny glass spheres. These meteors are unchanged since their formation, shortly after the formation of the sun. These meteors consist of elements also common in the Earth's core.

A meteorite is a meteor that has fallen to Earth. At least 100 meteorites hit the Earth every year. Meteorites have survived a fiery fall through the Earth's atmosphere and have lost a lot of mass in that process. Most meteorites burn up in the Earth's atmosphere; all that is left is a bit of dust. Every day, about 3000 tons of meteoroid dust falls to Earth.

There are different types of meteorites:

• Stony (92.8%):
  • Chondrites stony meteorites - 4.55 billion years old (from the formation of the solar system)
  • Carbonaceous Chondrites
  • Achondrites (7.1%): stony meteorites with chunks of differentiated matter that has melted and recrystallized
• Iron (5.7%) : crystalline iron-nickel alloy
  • Pallasites: the mineral olivine enclosed in metal
  • Mesosiderites
• Stony-iron: (1.5%) iron-nickel alloy and non-metallic mineral matter.

When meteorites hit the Earth they cause a crater to form. The bigger the meteorite, the bigger the crater.



The Biggest Meteorites

Barringer Crater in Arizona. This impact crater formed roughly 49,000 years when a 300,000 ton meteorite hit the Earth and disintegrated.

The biggest meteorite ever found on Earth is the Hoba meteorite. It weighed over 100 tons. This iron meteorite was found in Namibia, Africa. A lot of it has rusted away since it landed on Earth; it is still in its impact crater in Namibia

The largest meteorite ever found in the United States is Willamette meteorite (named for the city in Oregon where it landed). This iron meteorite weighed fifteen tons and was found in 1902.

Meteorite Web Links
Meteorites from NASA
Meteors from New England Meteoritical Services.
Meteorites from Mars - from NASA
Meteor crater activity from NASA

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