# Homework Assignment #6

Name:

Section number:

Due: Oct. 20

1. Compare the Orientale Basin on the Moon and the Caloris Basin on Mercury. What are the probable origins of the two features? Why?

2. Calculate the surface gravity on Mercury, and compare it to that on the Moon (1.7 m/s2). What does this tell us about the abilities of those two bodies to retain an atmosphere, as compared to the Earth (whose surface gravity = 9.8 m/s2)?

3. Argue from a comparison of their average densities whether or not:

• (a) Mercury (5.4 g/cm3) has a substantial metallic core?
• (b) Venus (5.2 g/cm3) has a core much like the Earth's (5.5 g/cm3)?
• (c) Mars (3.9 g/cm3) has a substantial metallic core?

4. An object's surface area-to-volume ratio is an indicator of whether or not it can retain its internal heat; the higher the ratio, the more quickly the object cools off. Calculate the surface area-to-volume ratio for the Moon, and for the Earth. How many times greater is the former quantity? Hint: area of sphere = 4*pi* r2; volume of sphere = 4 * pi * r3.