ASTRON 1101 Lecture Notes - Lecture 28: Milky Way, Spiral Galaxy, Parsec
5 Nov 2016
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Document Summary
Look up at night from a dark location; you will see a band of light called the milky way. Early explanations for the milky way were mythological. However, aristotle thought it was a fiery cloud in the earth"s upper atmosphere. When galileo looked at the milky way with his telescope, he found it was made of an immense number of stars. 1750: the english astronomer thomas wright explained the appearance of the milky. Way as due to our immersion in a flat layer of stars . 1785: william herschel (discoverer of uranus) and his sister caroline measured the shape of the milky way galaxy by counting stars in different directions. There was long debate whether the milky way galaxy is the only galaxy in the universe. 1845: the earl of rosse discovered spiral nebulae with his large telescope. First hypothesis: spiral nebulae are flattened disks of stars ( galaxies ) similar to the milky way.
