Stars & Galaxies
Stars & Galaxies AST-A 105
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This 3 page Class Notes was uploaded by Lauren Walther on Saturday August 29, 2015. The Class Notes belongs to AST-A 105 at Indiana University taught by Lugger P in Summer 2015. Since its upload, it has received 15 views. For similar materials see STARS AND GALAXIES in Astronomy at Indiana University.
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Date Created: 08/29/15
Stars and Galaxies 82515 Overview of class 82715 Lecture Astronomical Distances 1 meter m 394 in 11 yard 1 kilometer km 1000 m 06 mile 1 astronomical unit AU 150000000 km average distance between Earth amp Sun 1 light year ly 9500000000000 km distance light travels in a year Our Place in Space Earth rocky planet with iron core Sun typical star ball of hot gas mostly hydrogen amp helium Sun is 100x larger in diameter than Earth Volume of Sun is 1000000 times volume of Earth EarthSun distance 1 AU 100 X Sun s diameter 10000 X Earth s diameter Beyond the Solar System Milky Way Galaxy About 10000 ly across Contains about 100 billion stars Also contains gas and dust clouds from new stars form Cluster of galaxies Up to 10 million ly across Contain up to several thousand galaxies The Scientific Method Scientific Theory an idea that proposes to explain observations Scientific theories make testable predictions If theory is not consistent with new observations it is modified or discarded Observe theorize predict test modify Constellations Apparent groupings of bright stars on sky Stars in constellations are usually at large range of distances Stars in constellations are usually not physically associated Astronomical definition constellation sky region Sky is divided into 88 constellations Daily Motion of Sky Sky appears to rotate counterclockwise daily about Polaris the North Star Due to Earth s daily rotation from W to E Causes most celestial objects to rise in E and set in W For the picture the camera shutter was kept open for 4 hours Using your Sky Chart Relation to Sky Charts shows visible sky at one time Outer circle is horizon Dot sizes are proportional to apparent stellar brightness Constellations are shown as dotted lines Orientation Always turn the chart so that direction on the bottom is same as the direction you are facing Polaris amp the Dippers Face north Turn chart so north is at bottom The Little Dipper is now above Polaris in the evening Follow pointer stars to Polaris the North Star Big dipper is part of Ursa Major big bear Polaris is at end of handle of little dipper Ursa Minor little bear Rotated counterclockwise about Polaris The Summer Triangle High overhead in late summer early fall Formed by 3 bright stars Annual Constellation Cycle 0 Cannot see stars on side of sky containing sun 0 Only see stars located on side of sky opposite from Sun ie on the night side of Earth 0 As Earth orbits Sun different constellations become Visible Astronomy vs Astrology 0 Astrology is an ancient superstition not based on the scientific method Is not tested by observation or experiment
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