Difficulty: Hard

Average Score: 33%

Which of the following is a characteristic that distinguishes the giant outer planets in the solar system from Earth?

Rationale

They are made largely of hydrogen and helium.

The giant outer planets, known as gas giants, are primarily composed of hydrogen and helium, which significantly distinguishes them from the terrestrial planet Earth. This composition contributes to their vast sizes and low densities compared to the rocky planets.

A (They are made largely of hydrogen and helium.) CORRECT

This characteristic accurately describes the composition of the giant outer planets, such as Jupiter and Saturn, which have thick atmospheres dominated by hydrogen and helium gases. In contrast, Earth primarily consists of silicate rocks and metals, making this a defining feature that separates the two types of planets.

B (They are extremely dense.) YOUR ANSWER

While gas giants have substantial mass, they are not extremely dense. In fact, they have much lower densities than Earth due to their gaseous compositions. Earth, being a terrestrial planet, has a much higher density owing to its solid and metallic structure, rendering this choice incorrect.

C (They lack orbiting moons.) YOUR ANSWER

This statement is false as the giant outer planets possess numerous moons. For example, Jupiter has over 79 known moons, while Saturn has more than 80. In contrast, Earth has only one moon. Thus, the presence of moons is not a distinguishing characteristic.

D (They tend to have a shorter period of revolution around the Sun.) YOUR ANSWER

This choice is misleading because the giant outer planets actually take longer to complete an orbit around the Sun compared to Earth. For instance, Jupiter takes about 12 Earth years to orbit the Sun, while Saturn takes around 29 years. Therefore, this statement does not accurately differentiate them from Earth.

Conclusion

The giant outer planets are primarily made of hydrogen and helium, distinguishing them from Earth, which is composed mainly of rock and metal. Other proposed characteristics, such as density, moon presence, and orbital periods, do not accurately represent the differences between these planetary types. Understanding these distinctions is crucial for comprehending the diverse nature of planets within our solar system.

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