NATS 1880 Lecture Notes - Lecture 3: Milky Way, Mass Number, Chemical Energy
8 Jan 2017
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Document Summary
Greeks attempt to explain how cosmos moved. Newton"s universal gravity laws on why moved & made earth + heavens one. Universe is vast & old: lots of time & space for lbe to arise. Universal elements of life: chemical elements that made earth are in space too. Universal physical laws: laws of nature are the same everywhere. Solar system (sun, planets, moon, smaller objects) Milky way galaxy: collection of stars (>200 billion stars) & 100,000 ly diameter. Local group: our galaxy cluster (few dozen + large galaxies) Laniakea: local supercluster (clusters of galaxy clusters) Space: 300+ football elds in a grid to scale real life orbits with above objects. Palm size: can cover entire region in which humans have travelled (incl. moon) Light years: 1 light year = distance that light can travel in 1 year. (10 trillion km) ^ note: light year is a unit of distance, not time.
