# Astronomy assignment #10

(1) Jupiter and Saturn vs. Uranus and Neptune

We have compared the Terrestrial Planets and the Giant or Jovian Planets, but when we look at the 4 Giant Planets we can see that they can be paired into Jupiter and Saturn vs. Uranus and Neptune.

(2 pts.) (1a) Explain 3 similarities shared by all 4 giant planets.

(2 pts.) (1b) Explain 3 ways in which Uranus and Neptune differ from Jupiter and Saturn.

(2) Jupiter’s Great Red Spot
The GRS rotates completely in six days.

(3 pts.) (2a) If the spot is circular (not quite true, but a reasonable approximation for this matter) and 16,300 km in diameter, what are the wind speeds at the outer edges of the storm? Give you answer in km/hr. (Hints: Speed = distance÷time. How far does does a cloud on the edge of the spot move in one rotation? )

(1 pt.) (2b) How do these speeds compare with winds in terrestrial hurricanes where wind speeds can be 120 mph = 200 km/hr?

(3) Convince me!
(4 pts.) We know that Saturn has a density less than that of water – so the planet would float in a giant bath tub. If you tell your friends that a planet could float, they are likely to laugh at you. Describe HOW we know the density of Saturn is less than that of water by observing it from here on Earth – what quantities have been measured (units?)? Which formula (or formulae) is (are) used?

(4) Layers upon layers.
(3 pts.) Jupiter have several distinct layers of clouds. Why are these clouds separated into several distinct layers, so that clouds composed of a highly volatile gas such as ammonia found higher in the atmosphere than water?

(5) Colors.
(3 pts.) (5a) What gives Jupiter and Saturn their yellow/red colors?

(1 pts.) (5b) Describe the physical process(es) that make Uranus and Neptune look bluish.

(6) Receiving Signals from Jupiter.

(3 pts.) The distance from the Earth to Jupiter varies as the two planets orbit the Sun. Suppose we measure the distance to Jupiter and find that it is at a distance of 4.6 AU from the Earth,. How much time will it take for radio signals from a probe orbiting Jupiter to travel through space to reach us? Give your answer in minutes.

(7) Changes.

(2 pts.) Why does Uranus’ atmosphere show strong variations over the course of its orbit, Neptune and Saturn have moderate changes while Jupiter’s atmosphere appears pretty much the same, year in and year out? Please discuss each of these four planets by name in your response.

(8) The Solar System

(6 pts.) (8 a) In another solar system, we discover two terrestrial planets both with atmospheres made of 99% carbon dioxide. However, one planet has ten times more atmosphere than the other. Propose three hypotheses to explain why they would differ so much in their quantities of atmosphere.

(4 pts.) (8 b) Our solar system contains 4 terrestrial planets and 4 jovian planets. Suppose we discover another solar system with 8 terrestrial planets and no jovian planets. Propose a hypothesis to explain why the formation of that solar system would have turned out so differently from our own.

(4 pts.) (8 c) Why would astronomers be surprised to discover an active volcano on an asteroid?