Astronomy 1021 Chapter Notes - Chapter 1: Ecliptic, Big Bang, Office Of Gas And Electricity Markets
Document Summary
Astronomy 1021: chapter 1 a modern view of the universe. 1. 1 the scale of the universe geocentric: a belief in an earth-centered universe, usually held in ancient times. Galaxy cluster: groups of galaxies with more than a few dozen members. Superclusters: the area in which galaxies are most tightly packed. Our local group is located on the outskirts of a supercluster. Astronomical distance measurements: one astronomical unit (au) is the earth"s average distance from the sun, which is about 150 million kilometers. We use au to describe distances within our solar system. One light year (ly) is the distance that light can travel in one year, which is about 10 trillion kilometers. We use ly to describe the distances of stars and galaxies. Light travels at the speed of 300,000 kilometers per second, so one light second is 300,000 km. The farther away we look in distance, the further back we look in time.