Earth 120: Week 2 Note - The Universe
Earth 120: Week 2 Note - The Universe ERTH 120
Santa Ana College
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Popular in Earth Science
This 2 page Class Notes was uploaded by alicekhanh on Saturday April 2, 2016. The Class Notes belongs to ERTH 120 at Santa Ana College taught by Joanna Fantozzi in Spring 2016. Since its upload, it has received 27 views. For similar materials see Phys Earth/Space Systems in Earth Science at Santa Ana College.
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Date Created: 04/02/16
Chapter 23 + 24: The Universe 1. The Universe Ancients thought the Universe was geocentric (Earth at center) In the Renaissance, they thought it was heliocentric (sun at center) Everything that is known about the universe beyond our solar system has come from the analysis of the radiation emitted or reflected by the distant objects The Doppler Effect is the apparent change in wavelength of radiation caused by the relative motions of the source and observer Most galaxies exhibit a red Doppler shift, which means they are all moving away from us and the Universe is expanding! Formation of the Universe is now explained by the Big Bang theory All mass and energy started in a single point Exploded ~13.7 Ga and has been expanding ever since Current estimates predict an everexpanding, or open, universe 2. Galaxies Galaxies are collections of interstellar matter, stars, and stellar remnants that are gravitationally bound Spiral galaxy Barred spiral galaxy Elliptical galaxy Irregular galaxy 3. Star Every star moves through the stages of stellar evolution Birth o Start with a region of space filled with dust and gas o Attractive forces pull in more dust and gas and the vast cloud transformed to a disk shape Protostar o Fusion of hydrogen begins to form helium star “ignites” Mainsequence stage o Stars experience minimal changes in size and energy o Stars age at different rates large stars use fuel faster Red giant stage o Star’s surface cools and becomes red o Eventually all fuel is used Burnout and death final stage depends on mass o Lowmass star (<0.5 solar mass) Red giant collapses into a white dwarf o Highmass star (>8 solar masses) Supernova explosion Becomes a neutron star or black hole Star brightness is controlled by size, temperature, and distance The HertzsprungRussell diagram shows the relationship between brightness and temperature 4. Our Sun Our Sun is just one of 200 billion stars that make up the Milky Way