Astronomy 2021A/B Study Guide - Midterm Guide: Cosmic Microwave Background, Igneous Rock, Orion Nebula

• School: Western University
• Department: Astronomy
• Course: Astronomy 2021A/B
• Professor: Martin Zinke- Allmang

Document Summary

Milky way, is one of the two largest among more than 70 galaxies in local group. 1 light year is about 10 trillion kms. Nearest star system, alpha centauri, is about 4. 4 light years away. Orion nebula lies about 1350 light years away. The more massive the galaxy, the stronger its gravity and the faster stars should be orbiting. Dark energy is pushing galaxies apart even while gravity tries to draw them togethers. The radiation called cosmic microwave background, is prove that the universe expanded and cooled with time (proof for bigbang) If the bigbang occured, then the composition of universe should be hydrogens and helium. 4 hydrogen nuclei=1 helium nucleus, helium<4 hydrogen, so small amount become energy, e=mc2. When the fuel has been exhausted, star blows much of the content back to space, massive stars die in titanic explosion called supernovae. Stars like our sun can fuse helium into carbon, 3 heliums = 1 carbon.