AS101 Lecture Notes - Lecture 2: Cosmic Calendar, Milky Way, Astronomical Unit
Document Summary
1 au (astronomical unit)= average distance between the sun and earth= 150 million km. 1 minute light travels 300,000km x 60= 18 million km. 1 hour light travels 18 million km x 60= 1. 08 billion km. 1 day light travels 1. 08 billion km x 24= 25. 92 billion km. 1 year light travels 25. 92 billion km x 365= 9. 46 trillion km and sun varies at different points in its orbit. The earth"s orbit around the sun is elliptical. Therefore . universe size od 130,000,000,000,000,000,000,000km is 8. 67 tirllion au: minimum distance between earth and sun- perihelion= 148,000,000km, maximum distance between earth and sun- aphelion= 152,000,000km, 1 au= max distance + min distance /2= 150, 000,000 km. The earth is about 4 billion years old. On a cosmic calendar that compresses the history of the universe into one year, human civilization is just a few seconds old.
