Problem set 4 for ASTR 221: Stars and Planets

Due Wednesday Oct 16 at 5pm.

1. Scale heights of planetary atmospheres.
In notes we saw that the different planetary atmospheres, despite huge variations in atmospheric composition and planetary properties, are fairly similar. By calculating the relative scale heights of the atmospheres of Venus, Earth and Jupiter, explain why this is the case, and why the Earth's atmosphere has the lowest scale height of the three.

Kutner problems P25.1, P25.6, P25.10

Kutner problems P23.8, P23.9

Kutner Problems P24.4, P24.8

Roche Limit Problem (from Prof Mihos)
In class we calculated the Roche limit, which showed how close a moon could get to its parent planet before it will be tidally disrupted.
Saturn's moons are mostly icy bodies, with densities of about 1.2 g/cm3. Calculate the Roche limit for these moons. Compare this to the size of Saturn's rings, most of which lie within 120,000 km from the planet's center. Noting that all of Saturn's moons lie outside of 130,000 km from the planet' center, what does this suggest as one possible formation mechanism for Saturn's rings?
Calculate the Roche limit for the Moon. Is it in any danger of being disrupted any time soon?