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Lecture Tutorial: Properties of gas giant In this class, we’ve talked often about scale models, which give us a sense of the relative sizes and distances of objects in the . The , , and the have the following approximate diameters:

The Sun: 1,400,000 km Jupiter: 140,000 km Earth: 13,000 km

1. About how many times bigger is the Sun’s diameter than Jupiter’s diameter? (a) 2 (b) 5 (c) 10 (d) 100 2. About how many times bigger is the Sun’s diameter than Earth’s diameter? (a) 2 (b) 5 (c) 10 (d) 100 The last page of this tutorial shows the sizes of the Sun, Jupiter and the Earth, to scale.

3. Suppose you had been provided with this diagram, but not been provided with the actual sizes of the Sun, Jupiter and Earth’s diameters. Could you still have answered questions (1) and (2)? If so, how? If not, why not? 4. What three objects would make a good scale model of the Sun, Jupiter and the Earth (in that order)? (a) a basketball, a soccer ball and a baseball (b) a melon, a cherry, and a peppercorn (c) a basketball, a golf ball, and a ping-pong ball (d) an apple, an orange, and a cherry

The following figure shows the size of the sun in the sky as seen from each of the planets, plus .

1 5. Suppose John is floating out in space near Jupiter, and Maria is floating out in space near . Who will feel colder and why?

6. Suppose John is floating out in space near Jupiter, and Carla is floating out in space near Pluto. Who will feel colder and why?

7. The diagram below shows the temperature and pressure in Jupiter’s atmosphere. Suppose Juan is flying a spacecraft near the top of Jupiter’s atmosphere, where the pressure is 1 atm (1 atm is the same as the pressure on the surface of the Earth). He realizes he forgot a cup of water on top of the spacecraft a few hours ago. When he goes to get it, will the cup contain liquid, or ice? Explain your reasoning.

Jupiter orbits the sun on a nearly circular orbit with a radius of 5 Astronomical Units (AU). orbits the sun on a nearly circular orbit with a radius of 10 AU.

8. In the space below, draw the orbits of Jupiter and Saturn around the Earth, making sure their sizes are to scale.

2 9. On the orbits you just drew, draw two dots to represent Jupiter and Saturn at a time in their orbits when they are closest to each other. At this time, what is the distance between Jupiter and Saturn?

10. At this time, what is the distance between Jupiter and the Sun, in Astronomical Units?

Use the diagram you drew and your knowledge about Jupiter and Saturn to complete the following sentences: 11. During Jupiter’s orbit around the sun, it is (a) Always about the same distance between the Sun and Saturn (b) Almost always farther from Saturn than from the Sun (c) Almost always closer to Saturn than to the Sun

12. For an observer in a spacecraft orbiting right near Jupiter (a) the Sun and Saturn will be about the same size in the sky (b) the Sun will almost always look larger than Saturn (c) the Sun will almost always look smaller than Saturn

Jupiter and Saturn are composed mostly of and gas.

13. What do you think would happen if you tried to a spacecraft on Jupiter or Saturn?

14. The density of gas on the surface of the Earth is about 1 kg/m3. Although Jupiter is also made of gas, the average density of Jupiter is much higher — about 1000 kg/m3. Why do you think this is?

3 Jupiter

Earth

The Sun

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