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ASTR 100 Midterm 1 Notes

ASTR 100 Midterm 1 Notes - ASTR 100 Midterm#1 Notes 1 Class...

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Unformatted text preview: ASTR 100 Midterm #1 Notes 1 May 21, 2008 Class covers entire scale range from atomic nucleus to galaxy. Ephemerides - clay tablets of planetary positions, kept records of astronomic positions and changed it from a oral tradition to a written tradition JPL - emphemorious calulations current termonology used today Sidereal - star-based calander using the annual rising of Sirius in August of each year in order to predict the annual flooding of the Nile river each summer - important to cultivation (Egytian time) Chinese got correct length of the year, they also recorded naked-eye sunspots Mayan - complicated numbering system based off of 20(fingers and toes) and 13 (lunar cycles?). American Indian Astronomy - knowledge of phases of moon "many moons ago". Medicine Wheels - similar to Stonehenge in purpose Petroglyphs & Pictograms Calendar sticks - to mark time passage Polynesian Astronomy - used for navigation Celestial Sphere - huge imaginary sphere which holds all the celestial objects. Stars at different distances, telescope only tool to determine distance. 2 Poles - extension to infinity to earths spin axis - there is no place where the north celestial pole exists Right hand rule - thumb in air, fingers curled in - fingers provide direction of earth's motion through diurnal motion. -------------------------------------------------------------------------------------------------------------------Monday - June 16th inverse square law of light - star looks fainter the farther you get Apparent Magnitude System - was back wards, bigger numbers means extremely faint object that only biggest telescopes can detect, negative numbers equals brighter objects., magnitude system is logrithmic - REMEMBER: logrithmic, backwards & that one magnitude difference is equal to a ratio of 2.512 Photometer - measuring device to determine magnitude of stars ASTR 100 Midterm #1 Notes 2 Hipparchus wrong on Sirius's magnitude, it's brighter & has negative magnitude, not positive To know how far away stars are, we must find stellar parallax ` 19 trillion miles = one parsec Absolute Magnitude (STUDY) Be able to calculate parsecs into light years for stars. ...
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