General Astronomy - Spring
2011
Homework #10 - due April 18
1. (3 pt) What is the Copernican principle?
2. (4 pt) If the Hubble constant were found to be 120 km/s/Mpc, what
would be
the critical density of the Universe?
3. (3 pt) When the Universe was 0.1 seconds old, there were no
protons.
Explain why.
4. (3 pt) How
were the photons in cosmic microwave background produced?
5. (4 pt) There
is a 500 pc long ruler located 1 Gpc from Earth. You measure the
angular size of the ruler to be 0.15 arcseconds. What does that
imply about the geometry of the Universe?
6. (3 pt)
How can dark energy be distinguished from normal matter and energy?