ASTR 3 Lecture Notes - Lecture 1: Celestial Equator, Northern Hemisphere, Top

• School: UCSC
• Department: Astronomy and Astrophysics
• Course: ASTR 3
• Professor: Fortney

Document Summary

All atoms heavier than hydrogen and helium on earth were made in the deep interiors of stars over 4. 5 billion years ago. Sitting atop the surface of the earth, we are moving extremely fast. Our standard units of length are the light-year (how far light travels in one year) and the astronomical unit average distance between the earth and the sun (au) Planet --> solar system --> galaxy --> galaxy clusters --> universe. 2. 1: galileo was the rst to discover the milky way, 88 constellations ll the entire sky, and some can only be seen from a particular hemisphere. Earth"s equator: earth"s north celestial pole points at polaris, the north star. The main reason for seasons involves earth"s axis tilt (distance from the sun has nothing to do with it) The seasons depends on how earth"s axis affects the directness of sunlight. Every 6 months the tilt shifts, causing northern hemisphere summer then southern.