AST101H1 Lecture : establsihing our palce in the universe

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Michael Reid

Document Summary

4. 6 billion years ago, our universe was made of gas and dust. Shortly after, earth began to progressively form over time but it was not formed to the way it is today until 3 billion years ago. 70 million years ago, earth became a vibrant living place until 5 million years later a rock smashed into earth making the planet non-living. Different perspective: earth is small compare to the other planets as seen in pictures taken from further distances. Threats to earth from earth: climate crisis. Galaxy: several hundred billion or even trillion star collection. 1 light year is about 10(13) km (=10 trillion=10,000,000,000,000) Similarly for a light second, light hour )