AS101 Study Guide - Right Ascension, Celestial Pole, Celestial Equator
Document Summary
Two ways to write numbers: scientific notation (powers of 10( )) Place the decimal after the first nonzero digit. Count the number of places that the decimal point moved. If the decimal moves to the left, the power of 10 is positive, right negative. 1 au(astronomical unit)= average distance between earth and sun= 150 million km(1. 5*10 8 ) 1 ly (light-year)= the distance light travels in one year= 9. 46* 10 12 . 1 pc(parsec) = 3. 26ly= 3. 09* 10 13 . 1 mpc (megaparsec) = 1 million parsecs. Ex : avg. distance between the sun and jupiter =5. 2au. Distance to the nearest star other than the sun: 4. 37ly or 1. 34 pc. Distance to andromeda galaxy (one of the our galaxy"s near neighbours): 2. 6 million ly or. How far away is the nearest star alpha centauri = 4. 4 trillion km. So 4. 4 trillion km = 4400 scale km. Earth turning from west to east but sphere turning from east to west.
