ERSC 1F01 Lecture 1: Astro Lecture 1
19 Oct 2017
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The direction of the spin is counter clockwise (prograde) as one would observe frim above the north. An observer on earth who is approaching the sunset line would see: The sun is rising in the east and setting in the west because. The earth is rotating/spinning from west to east. The earth spins once in about 24 hours. How long does it take light reflected off the moon and traveling at a speed of 300,000 km/s to reach. Note: the greater the distance, the longer is the lookback time. The average earth-sun distance is 150 million (1. 5x10^8) km. It is more natural to express the distances in terms of the earth-sun distance. Astronomical unit (au) = the average earth-sun distance= 150,000,000km. 150,000,000km/300,000 km/s = 500s = 8min 20s = 8. 3 min. One light minute is the distance light travels in one minute.
