Astronomy 101
Spring 2001
3rd Midterm Exam

Rules: This examination is to be taken without help of books or papers or notes. It is to
be worked on individually; the Vanderbilt Honor Code applies. You may use calculators. Please write clearly.

The first 10 questions ask for very short answers, without explanations. Be very brief and to the point. Longer answers are expected for questions 11-17.  Each question has an assigned point value (in brackets), with the points totaling 100 for the exam.  While I don't expect you to write a book in a time-limited exam setting, I expect logically complete, though concise, answers.  Correct but incomplete answers, or incorrect answers with correct logical support will receive varying degrees of partial credit.

You must turn in your question sheet with your answer pages (or bluebook).

Name (printed):

Sign on the line below to indicate that you understand the rules of this exam and the Vanderbilt Honor Code:

     I understand the Honor Code of Vanderbilt University and pledge, by signing,
     that I have followed the rules of this exam and the Honor Code.

Signature: 


            a) Row (your row number,  where the front row of the class is #1):
            b) Section (right = far from exit doors or middle or left = near exit doors):
            c) Seat (within your row and section, where the left-most seat is #1):
Object
Semi-Major Axis
Diameter
(km)
Mass 
(Earth masses)
Mass
(solar masses)
orbital velocity
(km/sec)
Mercury
0.4 AU
4,878
0.055
 
48
Venus
0.7 AU
12,104
0.82
 
35
Earth
1.0 AU
12,756
1.0
0.000003 = 1/300,000
30
Moon
384,000 km
3,476
0.01
  
..
Mars
1.5 AU
6,794
0.11
 
24
Ceres
2.8 AU
...
...
 
18
Jupiter
5.2 AU
142,800
317.8
0..001 = 1/1000
13
Saturn
9.5 AU
120,540
94.3
0.0003 = 1/ 3,350
9.6
Uranus
19.2 AU
51,200
14.6
 
6.8
Neptune
30.1 AU
49,500
17.2
 
5.4
Pluto
39.5 AU
2,200
0.0025
  
4.7
Equations we have used:
vesc= (2GM/R)0.5
vave= (3kT/m)0.5
M*V* = MpVp
G = 6.67 x 10-11 N m2 / kg2
k = 1.38 x 10-16 gm cm2 / sec2 deg
  1. [3 pts] What is a black hole?

    2.  
  2. [3 pts] Where did comets form?

    3.  
  3. [3 pts] In one sentence or phrase of less than 20 words, describe generally all the planets discovered around other Sunlike stars.

    4.  
  4. [3 pts] The escape velocity from Pluto is about 1 km/sec.  If Pluto were made of rock instead of ice, such that it's average density was four times greater than its current density, what would be the escape velocity for Pluto?

    5.  
  5. [3 pts] What is the "snow line"?

    6.  
  6. [3 pts] List three general properties of the solar system that must be explained by any successful theory of solar system formation.

    7.  
  7. [3 pts] The escape velocity (vesc) from Mars is 5.0 km/sec.  If the average velocity (vave) of oxygen atoms high in the Martian atmosphere is only 1.5 km/sec, what will happen to this population of oxygen atoms over the next few hundred million years?

    8.  
  8. [3 pts] Which body is the most volcanically active object in the solar system?

    9.  
  9. [3 pts] Which solar system body almost certainly has a warm, liquid ocean deep beneath its icy crust?

    10.  
  10. [3 pts] What are the two most important constituents of the atmospheres of the four giant planets? What third component is also a significant component of the atmospheres of Uranus and Neptune?

    11.  
  11. [10 pts]  How are the concepts of "radial velocity" and "the Doppler Shift" related?

    12.  
  12. [10 pts] How did the giant planets grow to be so big?

    13.  
  13. [10 pts] Explain how our "origin of planets"  theory succeeds or fails to explain the planets thus far discovered around other stars.

    14.  
  14. [10 pts] Would you expect to find more impact craters on Io or Callisto? Why?

    15.  
  15. [10 pts] Describe, qualitatively, the method by which astronomers are now able to detect planets around other stars. Be sure to discuss what factor, or factors, fundamentally limit our ability to make these discoveries.

    16.  
  16. [10 pts] Assume a planet orbits a nearby star that is identical to the Sun and that the planet orbits at 1 AU from that star.  Assume we have not yet discovered this planet.  What is the smallest such planet (in terms of mass) that you could hope to detect with the best telescopes and detectors available today?

    17.  
  17. [10 pts] What is the Copernican Principle? Is it being tested by our discoveries of extrasolar planets or is it irrelevant to issues related to the existence of planets around other stars?