Astronomy 1021 Lecture Notes - Lecture 2: Small Solar System Body, Milky Way, Dwarf Planet

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Sarah Gallagher

Document Summary

Astronomy- chapter one summary: a modern view of the universe. Earth (104km) solar system (1010km=60au) milky way galaxy (1018km=100,000ly) local group (3x1019km=3 million ly) local supercluster (1021km=100 million ly) Our solar system belongs to the milky way galaxy. The universe is the sum of all matter and energy, encompassing the superclusters and voids and everything within them. The farther away we look in distance, the further back we look in time. Any snapshot of a distant galaxy is a picture of both space and time. Star- a large, glowing ball of gas that generates heat and light through nuclear fusion in its core. Planet- a moderately large object that orbits a star and shines primarily by reflecting the light from its star. Dwarf planet- is an object that meets the first two of the above criteria but has not yet cleared its orbital path. Asteroid- a relatively small and rocky object that orbits a star.