Astronomy 2232F/G Lecture Notes - Lecture 7: Silicate Minerals, Pyroxene, Enstatite
12 Feb 2017
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Document Summary
Meteorites: meteoroid survives atmospheric entry and lands on the surface. Move at high velocities ~11-72 km/s: quickly heated to ~2000 k. Outer layers are heated to sufficiently: melt and vaporize, creates fusion crust. Atmospheric friction during descent removes some of this material (ablation: commonly lose ~50% of their mass. Atmospheric gases surrounding body became ionized and form a plasma. Atoms emit light after capturing an electron or returning to their ground-state. Streak of light: falling or shooting star (meteor) Appear at an altitude of 90-120 km above earth"s surface: disappear at 10-30km. ~20,000 meteorites found on earth each year: masses > 100 grams, majority are never found. ~70-100 tons of extraterrestrial material accumulate on earth each day majority is dust sized particles. Meteorite find: collected meteorite without it being seen to fall. Meteorites are general given the name of their collection site. Fragments of projectile found iron, nickel, meteorite.
