Download Homework, August 29, 2002 AST110-6

Homework, August 26, 2006
AST110-6
Due Date: Thursday, September 2, 2006
1. Review Question 11, Chapter 1 (25%)
Define astronomical unit, ecliptic plane, and axis tilt. Explain how each is related to
the Earth’s rotation and/or orbit.
2. Problem 27, Chapter 1 (25%)
Distance by light. Just as a light-year is the distance that light can travel in 1 year, we
define a light-second as the distance that light can travel in 1 second, a light-minute as
the distance that light can travel in 1 minute, and so on. Calculate the distance in
kilometers represented by each of the following: 1 light-second; 1 light-minute; 1
light-hour; 1 light-day.
3. Problem 28, Chapter 1 (25%)
Driving to the Planets (and Stars). Imagine that you could drive your car at a constant
speed of 100 km/hr (62 mi/hr), even in space. (In reality, the law of gravity would
make driving through space at a constant speed all but impossible.)
a. How long would it take to drive all around the Earth? Assume you can drive across
both land and ocean. ( Hint: Use Earth’s circumference of approximately 40,000
kilometers.)
b. Suppose you started driving from the Sun. How long would it take to reach Earth?
How long would it take to reach Pluto? (You can find planetary distance data in
Appendix E.)
c. How long would it take to drive the 4.4 light-years to Alpha Centauri? ( Hint:
Remember that 1 light-year is approximately 10 trillion kilometers.)
d. Suppose you wanted to reach Alpha Centauri in only 100 years. How fast would
you have to go? Compare this speed to the speeds of our fastest current spacecraft
(around 50,000 km/hr).
4. Do an inventory of the planets of the solar system (using current definition):
(25%)
1. How many are rocky?
2. How many are gaseous?
3. How many are icy?
4. How many have moon(s)?
5. How many have rings?
6. How many support life?
7. What other common properties of the planets you can think of that can be added
to this list?