The Solar System – ASTR 121
First Midterm –April 20, 2012, 11:00-11:50
Instructions: Print your name and student identification number at the top of this page. Answer each of the questions A through J in the space provided. Be clear and thorough in your answers using sentences, sketches, and formulas where appropriate. Each question is worth two points.
A. Why do we see different stars in summer than in winter?
B. What is the Copernican Principle?
C. State Kepler’s second law of planetary motion.
D. Give an example of objects, still observable in the Solar System today, resulting from fragmentation. Explain.
E. Explain one way astronomers detect extra-solar planets (exoplanets).
F. Describe one contribution made by Islamic astronomers during the Dark Ages in Europe.
G. Why is it necessary to know the distance to a planet to determine its mass?
H. Explain how gravity is used to propel spacecraft through the Solar System.
I. Explain an everyday example of the use of parallax.
J. What is the time between sending a laser pulse and receiving its reflection from an object at a distance of about 6 x 106 km? (light travels at about 3 x 105 km/s)