AST201H1 Study Guide - Midterm Guide: Milky Way, Local Group, Falsifiability

Which of the following correctly lists our "cosmic address" fromsmall to large?

a.) Earth, solar system, Milky Way Galaxy, Local Group, LocalSupercluster, universe

b.) Earth, solar system, Local Group, Local Supercluster, Milky WayGalaxy, universe

c.) Earth, Milky Way Galaxy, solar system, Local Group, LocalSupercluster, universe

An astronomiclal unit (AU) is equal to the average distance fromthe Earth to the Sun, about 92.9 x 10^6 mi. A parsec (pc) is thedistance at which 1 AU would subtend an angle of exactly 1 secondof arc. A light-year (ly) is the distance that light, travelingthrough a vacuum with a speed of 186,000 mi/s, would cover in 1.0year.

1. Calculate whether the setting sun floats or sinks into thePacific Ocean each night.
2. Use the size of the Universe, assume 200 billion galazies, ourown is average, and 200 billion stars per galaxy, our Sun isaverage, to calculate the density of the known Universe.

The size of the universe (the average distance between galaxies) atany one moment is believed to have been inversely proportional tothe absolute temperature. Estimate the size of the universe,compared to today at:

a) t= 5 billion years

and

b) t= 1 hour