Name __ Answer Key ___
Astronomy 1510 - Quiz 2
A. Multiple Choice (5 points)
1.
All elements heavier than lithium come from ____ A ______. a. supernovae b. meteorites c. the Big Bang
2.
When Fritz Zwicky discovered that outlying galaxies in the Coma cluster move much faster than they would if the cluster’s mass were limited to that of the visible galaxies in it, he coined the term ____ B _______.
a. “dwarf galaxy” b. “dark matter ” c. “black hole”
3.
Unlike planets in our Solar System, galaxies do not move with Keplerian motion. Who noticed this?
a. Sandra Faber b. Margaret Geller c. Vera Rubin
4. The zone of habitability is defined as a.
the area between the Tropics of Cancer and Capricorn. b. the orbital radius at which the surface temperature of a planet is such that
liquid water exists. c.
that unique place in the Universe where stars like our Sun form.
5.
WIMPs and MACHOs are a.
two candidates for dark matter. b.
acronyms for space-exploring satellites. c.
terms for boxing champions.

B. Short Answer (20 points)
6.
Discuss the Steady State and Big Bang theories for the origin of the Universe. (4 points)
Steady State – Universe doesn’t change in large-scale structure; even though it’s expanding, matter is continuously created to fill in the voids
Big Bang – Universe expanded from a hot, infinitely dense state and occurred everywhere, not at one point; H, He, and some Li were created at that time
7. Explain how stars and planets form from a molecular cloud. (4 points)
1.
Molecular cloud collapses and starts to rotate (conservation of angular momentum).
2.
Debris forms in an accretion disk around the central star.
3.
Debris coalesces into planetesimals. Star begins to shine and blows away excess gas and dust.
4. Planetesimals combine to form planets.
8.
The term “large-scale structure” has been used to describe the way our Universe
looks. What does this mean? (4 points)
Galaxies tend to clump into groups, clusters, and superclusters; walls, voids, and bubbles, probably formed by galaxies and dark matter, are seen.
On cosmic scales, Universe in homogenous; on smaller scales, inhomogenous.
9. Explain the top-down vs. bottom-up theories for structure formation. (4 points)
Top-down – superclusters of galaxies broke down to form clusters, then groups, then individual galaxies
Bottom-up – galaxies formed first, then combined to form groups, clusters, and superclusters
10. List four members of our Local Group. (4 points)
The Milky Way
Andromeda (M31)
M33
Large Magellenic Cloud
Small Magellenic Cloud
M32