AST101H1 Lecture Notes - Iceberg, Ecliptic, Observable Universe

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

Document Summary

We live in an earth-centered (geocentric) universe. Different theories explaining space/earth but slowly evolved to what we know today (earth is flat, sun-centered, etc) Planet in the solar system (consists of sun and all objects that orbit it like planets, stars, moons, asteroids and comets) Sun = just 1 star in huge collection of stars called the milky way. Galaxy = great island of stars in space (trillion stars) Galaxy clusters = group of galaxies w/more than a few dozen members. Superclusters = galaxies/group of galaxy clusters tightly packed. Universe = the sum total of all matter and energy, encompassing the superclusters and voids and everything within. Humans are newcomers in an old universe. The big bang and the expanding universe: entire universe is expanding = average distances b/w galaxies are increasing with time. Galaxies must have been closer in the past: the beginning = big bang (14 billion years ago, while universe expands, ind. galaxies/galaxy clusters don t.