ESC 1000 Lecture Notes - Lecture 37: Blueshift, Edwin Hubble, Redshift
Document Summary
The study of the structure and evaluation of the universe. "before the common era" aka bc time period. The earth is the center of the universe, theory proposed by ptolemy 100-170 ce (egypt) The sun is the center of the universe, theory proposed by copernicus 1473-1543 (renaissance) Eratosthenes calculated the earth"s circumference to be 39,300km twenty two centuries ago. (actually. 200 bce mathematicians calculated the distance to the moon to be 382,260km (actually 381,555km), Closest star to earth, lies 40. 85 trillion km away. The distance that light travels in one earth year, 9. 5million km or 6 trillion miles. Lies over 13 billion light years away, which means light traveling to earth from this location began it"s journey about 9 million years before the earth existed. Stars aren"t randomly located in the universe, gravity pulls them into systems known as galaxies. the sun is one of over 300 billion stars in our galaxy, the milky way.
