ASTR 1050 Exam 2 Results

You can view a scan of your submitted exam through WyoCourses or directly through Gradescope.  Gradescope also shows how much credit was awarded to each of the exam questions.

Answers to the Questions

Multiple choice

Question	Answer
1	a, b, c, d
2	c
3	a
4	b
5	d
6	refractor refractor reflector
7	b
8	c
9	d, e
10	d
11	b
12	d
13	b
14	TRUE
15	TRUE
16	b, c
17	a, c, d
18	b
19	a
20	a
21	a
22	Highlands
23	Maria
24	Highlands
25	c
26	a
27	a
28	TRUE
29	TRUE
30	FALSE
31	FALSE
32	a
33	a, d, e

Free Response

Question 34 The relationship is c = λf.

Question 35 The principal triggers identified in class are a supernova explosion, light pressure from an energetic young star, and collision of nebulas.  Merely stating that a matter overdensity causes a collapse is insufficient: overdensities don’t appear with out a reason.  This question wanted you to identify three reasons.

Question 36 Parts A–C asked for evidence against three hypotheses.  Part D asked for reasons why the Giant Impact hypothesis is consistent with the evidence that questions the others.

1. Orbital capture  If the Moon were captured, we'd expect it not to be isotopically essentially the same as Earth.  Meteorites and samples on Mars are different from Earth isotopically.
2. Fission  It’s hard to imagine a plausible way that Earth could have been set spinning so fast that it would split apart.
3. Co-creation   If Earth and the Moon were formed from the same solid dust, both should have similar amounts of light and dense materials in their composition.  But Earth has much more of the heavy stuff, namely iron and iron-containing minerals.
4. Giant Impact  If the Moon were initially part of the Earth, its isotopic composition should be the same as Earth’s.   Giant Impact doesn’t require fast spin, just a collision.  That is easier to envision.  But if the Earth had already differentiated into an iron-rich core and rocky mantle before the impact, the outer, lighter mantle should have been the source of most of the material ejected by the impact, leaving the core in place.  Giant Impact neatly explains all of the observations that are problematic for the other mechanisms.

Question 37 One point was awarded for each unique feature of planet Earth correctly identified.  Some distinct ways mentioned were Earth's large size, atmosphere containing oxygen as O₂, liquid surface water, strong magnetic field, plate tectonics, large moon, active erosion, life, and weather (including rain).

Question 38 From top to bottom, the three circled features are a crater, a mare, and a highland.

Question 38 Full credit was awarded here if you identified a topic that could have been on the exam but wasn’t.  Less credit was awarded if you identified something that wasn’t in the list of topics covered by the test, or if you identified something that was in one of the exam questions.