Question 5.1

About how long after the universe came into existence did our solar system form?

1. 0 years (they formed together)
2. a million years
3. 10 million years
4. a billion years
5. 10 billion years

Question 5.2

Pluto is most similar in composition to which of the following objects?

1. Eris
2. Jupiter
3. our Moon
4. Earth
5. the Sun

Question 5.3

Which planets are terrestrial and which are giant?

Question 5.4

What is the Nice model’s explanation for why there is no planet in the vicinity of the asteroid belt.

Question 5.5

Describe four methods for discovering exoplanets.

Question 5.6

Which giant planet formed first?

Question 5.7

According to the Nice theory, where did the Kuiper belt objects and Oort cloud objects come from?

Question 5.8

What created most of the craters in the solar system? What else could create craters? (Hint: Think of craters on Earth.)

Question 5.9

Jeans instability is responsible for what event in the life of the solar system?

Question 5.10

Name and briefly describe one small solar system body.

Question 5.11

Name one dwarf planet (other than Pluto) and state where it is located.

Question 5.12

Asteroids, meteoroids, and comets are also classified as what (one) kind of object today?

Question 5.13

What two properties of a planet must be known to determine its average density? How are these properties determined?

Question 5.14

How can Neptune have more mass than Uranus but a smaller diameter? (Hint: See Table 5-2.)

Question 5.15

How would a planet orbiting one of the first-generation stars be different than planets formed today? What chemical elements would that planet contain? Could we humans exist on that world? Why or why not?

Question 5.16

What is significant about the snow line described in this chapter?

Question 5.17

Earth had a highly elliptical orbit, like Mercury? What would be different about Earth and life on it?

Question 5.18

The accretion process of planet formation were still ongoing in the solar system? How would life on Earth be different, in general, and how might humans be different?

Question 5.19

The solar system passed through a cloud of gas and dust that was beginning to collapse to form a new star and planet system? What might happen to Earth, and how would the passage affect the appearance of the sky?

Question 5.20

Search the Web for information about recent observations of protoplanetary disks. What insights about the formation of the solar system have astronomers gained from these observations? Explain the evidence astronomers have, from these observations, that planets are forming in these disks.

Question 5.21

In 2000, exoplanets with masses comparable to the mass of Saturn were first detected around the stars HD 16141 (also called 79 Ceti) and HD 46375. Search the Web for information about these planets. How do their masses compare to previously discovered exoplanets? Do these planets move around their stars in the same kind of orbit as Saturn follows around the Sun? If not, explain the differences.

Question 5.22

Search the Web for information about the planet that orbits the star HD 209458. This planet has been detected using two methods. What are they? What have astronomers learned about this planet?

Question 5.23

Access the animation “Planetary Orbits” in Chapter 5 of the Discovering the Universe Web site. Focus on the motions of the inner planets during the last half of the animation. Using the stop and start buttons, determine how many days it takes Mars, Venus, and Mercury to orbit the Sun once if it takes Earth approximately 365 days.

Question 5.24

Search the Web for information about the cool, dim star Gliese 581. What is its mass compared to our Sun’s? How bright is it (in other words, what is its luminosity) compared to the Sun? How many planets are known to be orbiting it? How do their masses compare to the mass of Earth? What is special about the planet Gliese 581c?

Question 5.25

Which elements on Earth were created during the Big Bang?

Question 5.26

How long has the universe existed and how long has the solar system existed?

Question 5.27

Name an object on Earth that is most similar in shape to a typical moon in our solar system.

Question 5.28

Of the four giant planets, which gets the most radiation from the Sun? Explain why (Tables 5-1 and 5-2 might help).

Question 5.29

Use Starry Night™ to make observations of the solar system. Select Favourites > Explorations > Solar System. The view shows the names and orbits of the major planets of the solar system against the backdrop of the stars of the Milky Way Galaxy, from a location hovering 64 AU from the Sun. You may also see many smaller objects moving in the asteroid belt between the orbits of Mars and Jupiter. (If not, select View > Solar System and click on the Asteroids box.) (a) Use the location scroller to look at the solar system from different angles, and observe the general distribution and motion of the major planets. Make a list of your observations. (b) How does the nebular hypothesis of solar system formation account for your observations?

Question 5.30

Use Starry Night™ to examine magnified images of the terrestrial major planets Mercury, Venus, Earth, and Mars and the dwarf planet Ceres. Select each of these planets from Favourites > Explorations in turn. Use the location scroller cursor to rotate the image to see different views of the planet. (a) Describe each planet’s appearance. From what you observe in each case, is there any way of knowing whether you are looking at a planet’s surface or at complete cloud cover over the planet? (b) Which planet or planets have clouds? If a planet has clouds, open its contextual menu and choose Surface Image/Model > Default and use the location scroller to examine the planet’s surface. (c) Which major planet shows the heaviest cratering? (d) Which of these terrestrial planets show evidence of liquid water? (e) What do you notice about Venus’s rotation compared to the other planets?

Question 5.31

Use Starry Night™ to examine the Jovian planets Jupiter, Saturn, Uranus, and Neptune. Select each of these planets from Favourites > Explorations. Use the location scroller cursor to examine each planet from different views. (a) Describe each planet’s appearance. Which has the greatest color contrast in its cloud tops? (b) Which planet has the least color contrast in its cloud tops? (c) What can you say about the thickness of Saturn’s rings compared to their diameter?

Question 5.32

Use Starry Night™ to investigate stars that have planets orbiting them. Click the Home button in the toolbar. Open the Options pane and use the checkboxes in the Local View layer to turn off Daylight and the Local Horizon. Expand the Stars layer in the Options pane and then expand the Stars item and check the Mark stars with extrasolar planets option. Then use the Find pane to find and center each of the stars listed below. To do this, click the magnifying glass icon on the side of the edit box at the top of the Find pane and select Star from the dropdown menu; then type the name of the star in the edit box and press the Enter or Return key on the keyboard. Click on the Info tab for full information about the star. Expand the Other Data layer and note the luminosity of each of these stars. (a) Which stars are more luminous than the Sun? (b) Which are less luminous? (c) How do you think these differences would have affected temperatures in the nebula in which each star’s planets formed? (i) 47 Ursae Majoris (3 known planets); (ii) 51 Pegasi (1 known planet); (iii) 70 Virginis (1 known planet); (iv) Rho Coronae Borealis (1 known planet).