PHYS-UA 11 Study Guide - Midterm Guide: Local Group, Edwin Hubble, Ures
5 Nov 2016
School
Department
Course
Professor
Document Summary
Our solar system belongs in a giant disk-shaped collection of stars called the milky way: galaxies usually are in groups. Our milky way is one of two large galaxies in the local group; a collection of about 70 galaxies, many of which are smaller than ours. Clusters of galaxies with many more large members are called galaxy clusters: on a huge scale, galaxies and galaxy clusters seem to be arranged in giant chains and sheets, with huge voids between them. About 150 million km, or 93 million miles: light year (ly): the distance light can travel in one year, which is about 10 trillion kilometers. Used to de ne distances between stars and galaxies: the farther away we look in the distance, the farther back into time we see. Andromeda galaxy is 2. 5 million light-years away, meaning that the light we see from it took 2. 5 million years to reach us.
