ASTR 1000 Lecture Notes - Lecture 2: Scottish Reformation, Cambrian Explosion
6 Sep 2016
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Jan. 1st the big bang: plasma at extreme temperatures cooled down and collapsed to form stars and galaxies, atmosphere = 90% hydrogen & 10% helium. Dec. 17th cambrian explosion (14 billion years ago) (4. 54 billion years ago) (3. 5 billion years ago) (210 million years ago: explosion of multi-celled and larger animals. Dec. 31st today: 9pm: early hominids, 11:58pm: modern humans, 25 secs ago: agriculture, 11 secs ago: pyramids built, 1 sec. ago: earth orbits the sun (50-210,000 years ago) Dating rock layers: discovered in 1700s-1800s (scottish reformation) 88 constellations: constellations each constellation represents a different region, n. hemisphere = named after greek legends, s. hemisphere = named after white european explorers. Horizon where the sky meets the ground. Altitude angular height above the horizon, in degrees. Fist at arms" length = about 10 degrees. Finger at arms" length = about 0. 5 degrees.
