AST201H1 Midterm: Midterm Study Notes

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Michael Reid

Document Summary

The universe is the totality of all space, time, energy, and matter. * the age and size of the universe. The univserse is about 13. 7 billion years old. The size of the universe is a tough question to answer. So, a better question to ask is how much of the universe can we see. But, if the universe is 13. 7 billion years old, the light from the galaxy would not have reached you yet. It will take 86. 3 billion years before the light reaches us. Therefore, there is limit imposed by nature to how far we can see: observable universe vs. unobservable universe. So, whenever we mention/refer to the term universe we will usually mean the observable universe. * light travel time and the light year. Speed of light = c = 300 million m/s. A light year is the distance light travels in one year: 1 ly = 9. 46 x 1015 m or 9. 46 trillion km.