AST101H1 Lecture Notes - Lecture 1: Milky Way, Virgo Supercluster, Nuclear Fusion

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Ian Shelton

Document Summary

Our cosmic address: earth > solar system > milky way galaxy > local group > local. The farther away we look in distance, the further back we look in time. Astronomical unit (au): earth"s average distance from the sun, about 150 million km. Light-year (ly): the distance light can travel in one year, about 10 trillion km, unit of distance. Star: large, glowing ball of gas that generates heat & light because of nuclear fusion at its core. Planet: moderately large object that orbits a star, shines by reflecting the light of that star. Is large enough for its own gravity to make it round, has cleared most other objects from its orbital path. Asteroid: relatively small & rocky object orbiting a star. Comet: relatively small & icy object orbiting a star. Star system: a star(s) that is orbited by materials/planets. Galaxy: a great island/cluster of stars, all held together by gravity & orbiting a common center.