Gizmo Solar System Explorer Answer Key -100% Correct All Correct Questions & Answers 100% Correct

Solar System Explorer Answer Key

Vocabulary: astronomical unit, dwarf planet, eccentricity, ellipse, gas giant, Kepler’s laws, orbit,

orbital radius, period, planet, solar system, terrestrial planet

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

[Note: The purpose of these questions is to activate prior knowledge and get students thinking.

Students are not expected to know the answers to the Prior Knowledge Questions.]

1. List all of the planets you can think of in our solar system. Try to list them in order from

closest to farthest from the Sun.

Answers will vary. [Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune]

2. Which planets are most like Earth? Which are most different from Earth? Explain.

Answers will vary. [Venus and Mars are both rocky planets that contain atmospheres.]

Gizmo Warm-up

The Solar System Explorer Gizmo™ shows a model of the solar

system. All of the distances, but not the sizes of the planets, are

shown to scale. To begin, turn on Show orbital paths and click

Play ( ). You are looking at the four inner planets.

1. In which direction do planets go around the Sun, clockwise

or counterclockwise? Counterclockwise

2. An orbit is the path of a body around another body. What is the shape of the planetary orbits

around the Sun? Planetary orbits are nearly circular.

3. Click Pause ( ). You can see the name of each planet by holding your cursor over the

planet. What is the order of the eight planets, starting from the Sun? Click the “zoom out”

button ( ) to see the outer planets and Pluto, which is classified as a dwarf planet.

The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

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Activity A:

Classifying

planets

Get the Gizmo ready:

 Click Reset ( ).

Question: How are planets classified?

1. Think about it: How do you think astronomers group planets? Answers will vary.

2. Gather data: Select Mercury from the Solar system menu at left. Turn on Additional data.

In the table below, record Mercury’s Mass, Mean radius, and Density. Then repeat for each

of the other planets as well as the dwarf planet Pluto. Include units.

Planet Mass (×1023 kg) Mean radius (km) Density (g/cm3

)

Mercury 3.3 ×1023 kg 2,440 km 5.427 g/cm3

Venus 48.7 ×1023 kg 6,052 km 5.243 g/cm3

Earth 59.7 ×1023 kg 6,378 km 5.515 g/cm3

Mars 6.4 ×1023 kg 3,397 km 3.933 g/cm3

Jupiter 18,990 ×1023 kg 71,490 km 1.326 g/cm3

Saturn 5,680 ×1023 kg 60,270 km 0.687 g/cm3

Uranus 869 ×1023 kg 25,560 km 1.270 g/cm3

Neptune 1,020 ×1023 kg 24,760 km 1.638 g/cm3

Pluto (dwarf planet) 0.1 ×1023 kg 1,195 km 1.750 g/cm3

3. Analyze: What patterns do you notice in your data table?

Answers will vary. [Mercury, Venus, Earth, and Mars all have masses below 100 ×1023 kg,

radii below 10,000 km, and densities greater than 3.0 g/cm3

. Jupiter, Saturn, Uranus, and

Neptune all have masses above 800 ×1023 kg, radii above 20,000 km, and densities less

than 2.0 g/cm3

. Pluto has characteristics of both groups.]

4. Analyze: Based on the data you have collected, how would you divide the planets into two

groups? Explain your reasoning. (Note: Do not include Pluto in these groups.)

Answers will vary. [Astronomers divide the planets into two groups, the terrestrial planets

(Mercury, Venus, Earth, and Mars) and gas giants (Jupiter, Saturn, Uranus, and Neptune).]

(Activity A continued on next page)

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Activity A (continued from previous page)

5. Classify: Astronomers classify the eight planets in our solar system into two groups:

terrestrial planets and gas giants. Terrestrial planets have rocky surfaces, while gas giants

are composed mainly of gas. Based on your data, classify each planet as a terrestrial planet

or a gas giant. (Hint: Look at the density of each planet.)

Mercury: Terrestrial planet

Venus: Terrestrial planet

Earth: Terrestrial planet

Mars: Terrestrial planet

Jupiter: Gas giant

Saturn: Gas giant

Uranus: Gas giant

Neptune: Gas giant

6. Summarize: Compare the masses, radii, and densities of the terrestrial planets and the gas

giants.

A. What do the terrestrial planets have in common?

The terrestrial planets are all relatively low in mass and radius and high in density.

B. What do the gas giants have in common?

The gas giants are all relatively high in mass and radius and low in density.

7. Extend your thinking: Why doesn’t Pluto fit into either the terrestrial planet group or the gas

giant group?

Pluto’s radius is too small to be classified as a gas giant. (Pluto is also small for a terrestrial

planet.) Pluto’s density is too low to fit into the terrestrial group and its density is too high to

fit into the gas giant group. [In fact, Pluto is made of frozen ice.]

8. Think and discuss: Why do you think the inner planets are small and dense, while the outer

planets are gas giants? If possible, discuss your ideas with your classmates and teacher.

Answers will vary. [For an explanation, see the last page of the Teacher Guide.]