Astronomy 3 - Problem Set 8

1. Describe the location of the equinoxes and solstices in the Uranian Sky. What are the seasons like on Uranus?
2. Given the size of Triton's orbit (R = 355,000 km) and its orbital period (P = 5.877 days), calculate the mass of Neptune.
3. How can Titan keep an atmosphere when it is smaller than airless Ganymede?
4. If you piloted a spacecraft to visit Saturn's moons and wanted to land on a geologically old surface, what features would you look for? What features would you avoid?
5. A relatively small impact crater 20 km in diameter could be made by a comet 2km in diameter traveling at 30 km/s. Assume that the comet has a total mass of 4.2 billion tones (4.2 x 10^12 kg). What is its total kinetic energy? (Hint check chapter 4 of the book). If one megaton of TNT releases 4.2 million billion (4.2 x 10^15 joule), how many megaton does the energy released by the comet correspond to? How often do impact of this magnitude occur on the Earth?
6. If comets are icy planetesimals left over from the formation of the solar system, why haven't they all vaporized by now?
7. What is the difference between the location where most asteroids are located and that where comets originated from? What is the compositional difference between comets and asteroids?
8. What evidence do we have that some meteorites have originated inside large bodies?