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Chapter 29-30 The Universe Section 1 The Sun 1.) Sun’s gravity holds planets in orbit. 2.) Planet’s orbits and make up is related to distance from sun. 3.) Sun’s energy life Sun’s Body -average star -109 x larger than Earth’s diameter -333000 x mass of Earth - 99.85% of all mass in solar system. 1. Core - H and He - 15 million degrees C -plasma 2. Radiation Layer -heated by core through radiation - 3 million degrees C 3. Convective Layer -energy transformed by convection currents - 1.1 million degrees C 4. Photosphere “sphere of light” - visible surface (like bubbling pots surface) 5500 degrees C -Granules =small bright area =tops of rising columns of gas =darks areas are sinking areas Sun’s Atmosphere 1. Chromosphere- above photosphere - “sphere of color” bright red - 2500 km thick - 100,000 degrees C (hotter!) -only seen during solar eclipse photosphere is blocked -Solar prominences- erupting clouds of gas that fall back to sun Motions & Activities of Sun -energy at Earth now was created at sun’s core about 3000 yrs ago H+HHe+ energy (FUSION) -moves slowly to surface and become light -8 minutes (light earth) -rotates on its axis (counterclockwise) but not all areas rotate at same speed Slower at poles At equator, 1 sun day= 25 earth days -sunspots- dark areas of intense magnetic activity -cooler (dark) - 11 yr cycle (quiet now) - t;-; ions speed up and escape surface -causes increased solar wind -solar flares-eruptions near sun spots. Solar wind reaching earth disturbs magnetic field and communications causes Auroras. Section 2 Other Stars Star= mass of H & He Universe= all the matter and energy that exists Clump of dust bigger hotter 1 million degrees C STAR (fusion) New stars are still forming! (orion) H & H He Glows Group of stars= constellation Ancient Greeks (44) Today (88) Star in a constellation aren’t really related. North Star (POLARIS) doesn’t move! TRUE NORTH Others move around it depending on time of day and year. Brightness Apparent magnitude- brightness as it appears from Earth. Depends on 1. how much light is emitted. 2. Distance from Earth Absolute magnitude= luminosity How much light is really emitted. Ancient Greeks- 6 magnitudes 1st magnitude- brightest 2nd 3rd 4th 5th 6th barely visible with unaided eye -telescope- 25th magnitude is visible - negative magnitude are very bright Sun(-27) Orion’s rt shoulder= Betelgeuse Lt leg= Rigel Sirius- follow orion’s belt to lt. “dog star” brightest star in sky -1.45 -Supernovas - brightest of all stars (once thought to be a new star) “new” - end of life; exploded blowing matter intospace - brightest 100s of billions x brighter for days or years - Star’s color and temp. are related Blue---------- Reddish Hottest Color Hertzsprung Russell Diagram p. 605 Super giants- largest brightest Dwarfs- smallest ; densest; dimmest Discover by Dong p 604 -sun is middle aged -all H will be suded up in another 4.6 billion yrs -core will contract/ temp ^/ surface expands -will become a red giant = old star, expanded with low surface temp. (Mercury and Venus will burn up) -core gets hotter/ surface blows off= white dwarf (fusion stops) - (small but dense!) cools for billions of years black dwarf(cold cinder) Neutron Stars and Black Holes Large star development H in core is depleted; Core can’t support weight; Shrinks violently and may explode= SUPERNOVA -90% of mass is scattered and collects in a dust cloud= NEBULA - 10% (core) falls inward NEUTRON STAR (very small) Very dense -may rotate and have magnetic field -may give off radio waves (look like blinking light) PULSAR -if core of supernova is 3x mass of sun collapse Greats a black hole (gravity won’t allow energy to escape). Section 3 Galaxies Distance in space is measured on LIGHTYEARS- Distance that light travels in 1 yr. ~10 billion km Sirius (Dog star) only 9 light years away Proxima Centauri (closest) 4.25 light yrs Other than sun Galaxy- large grouping of stars -our solar system is part of Milky Way Galaxy - what we see as the Milky Way is only the edge (spiral galaxy) Andromeda Galaxy 2.3 m.l.y. Seen in Andromeda (spiral) Large & small Magellanic Clouds- seen from s. hemisphere 27 others seen through telescopes Billions of Galaxies Great Wall- huge group of galaxies -not held together by gravitation Quasars- (quasi-stellar radio source) -don’t show up as visible light - small, fast-moving star-like objects - may be oldest objects in universe - emit lots of energy - may be near black holes Big Bang Theory 15 billion yrs ago – explosion - eventually cooled and clumped together * universe is still expanding Light changes color as source moves toward or away form viewer Light moving away Red Light moving toward us Blue * all far away galaxies are moving away ( red shift)