ASTR 100 Lecture Notes - Ammonia
3 Apr 2014
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Document Summary
Comets & cosmic catastrophes: collision by yucatan peninsula, found because there is iridium surrounding the impact site, k t boundary event, cretaceous tertiary, comets, tycho brahe (1577) no parallax, saw no parallax and proved it was not an atmospheric event, sir william huggins (1888) identified carbon lines in their spectra, first to make sense of the lines, newton, first to calculate orbits of halley"s comet, structure: nucleus, coma, and two tails, nucleus, called a dirty snowball a. Icy component and particles of dirt/rock in it: diameter 15 km 20 km prolate spheroid, mean density 100 kg/m^3, albedo 4, coma: a cloud of gas with jupiter"s diameter, occurs as the comet gets inside mar"s orbit, water starts to vaporize into gas, tails: up to 1 au in length, don"t form until the coma forms and the win from the sun starts to blow the particles out, usually has two tails.
