Problem #1: a) The Sun orbits the center of the Milky Way galaxy in roughly a circle of radius 23000 light years, and with a speed of 220 km/s. Calculate the time required for the Sun to complete one circuit around the galaxy.
b) How many times will the Sun orbit the galaxy in its 10 billion year lifetime?
Problem #2:a) Rydberg's constant, which we calculated in Lab #3, and which is the energy required to ionize a hydrogen atom from the ground state, is equal to 2.18 x 10-19 Joules. Calculate the wavelength of a photon which has this energy.
b) Determine the surface temperature of a star whose blackbody spectrum peaks at this wavelength.
Problem #3:a) The nearest "real" galaxy to us is the Andromeda Galaxy, also known as M 31. This galaxy has an apparent size of 2 degrees (about four times the size of the full moon!). If its linear size is 25 kpc, how far away from us is it?
b) How long does it take for light from that galaxy to reach us?