Astr Chap 19 - The Expanding Universe Study Guide Rated A+

In the early 1960s, physicists named Penzias and Wilson detected a persistent noise at a wavelength of 1 mm in their radio telescope that came from all directions in the sky due to: {Ans: photons left over from the Big Bang}What do astronomers mean when they say that the universe is isotropic? {Ans: The universe looks the same no matter what direction you look.}The apparent recessional velocities of galaxies at large distances are due mainly to the actual motions of the galaxies through space. {Ans: False}Galaxies move away from us in all directions because: {Ans: Space is expanding}Is dark energy responsible for the expansion of the universe? {Ans: No. The expansion would happen without dark energy, but dark energy is causing the expansion rate to increase.}Charles Messier published the first galaxy catalog containing over 2,000 nearby galaxies. {Ans: False}