23.3 Exploring Outer Planets and Pluto

Which of the following is a characteristic of the outer planets?

• They have solid surfaces.

• They are primarily composed of gases.

• They are closer to the Sun than the inner planets.

• They have no moons.

Answer explanation

The outer planets, also known as gas giants, are primarily composed of gases like hydrogen and helium, unlike the inner planets which have solid surfaces. This makes the correct choice about their composition.

How do the sizes of the outer planets compare to each other?

• Jupiter is the smallest.

• Neptune is the largest.

• Saturn is larger than Uranus.

• Uranus is larger than Jupiter.

Answer explanation

Among the outer planets, Saturn is indeed larger than Uranus. Jupiter is the largest, followed by Saturn, Uranus, and Neptune, making the statement 'Saturn is larger than Uranus' the correct choice.

Explain why Pluto is classified as a dwarf planet.

• It is smaller than Earth's moon.

• It does not orbit the Sun.

• It has not cleared its neighboring region of other objects.

• It has no atmosphere.

Answer explanation

Pluto is classified as a dwarf planet because it has not cleared its neighboring region of other objects, which is one of the key criteria for full planet status. This distinguishes it from the eight major planets.

Which outer planet has the most complex and extensive ring system?

• Jupiter

• Saturn

• Uranus

• Neptune

Answer explanation

Saturn is known for its stunning and complex ring system, which is the most extensive among the outer planets. Its rings are made up of ice and rock particles, making them more prominent and intricate than those of Jupiter, Uranus, or Neptune.

Analyze the atmosphere of Jupiter. What is it primarily composed of?

• Oxygen and nitrogen

• Hydrogen and helium

• Carbon dioxide and methane

• Sulfur dioxide and water vapor

Answer explanation

Jupiter's atmosphere is primarily composed of hydrogen and helium, making it similar to the Sun. The other options, such as oxygen, nitrogen, carbon dioxide, and sulfur dioxide, are present in much smaller amounts.

Discuss the significance of moons in the outer planets. Which planet has the largest moon in the solar system?

• Jupiter

• Saturn

• Uranus

• Neptune

Answer explanation

Moons play crucial roles in the dynamics and geology of outer planets. Jupiter's moon Ganymede is the largest in the solar system, showcasing the planet's significant gravitational influence and diverse satellite system.

Evaluate the distance of Neptune from the Sun compared to the other outer planets.

• It is the closest to the Sun.

• It is the second closest to the Sun.

• It is the farthest from the Sun.

• It is closer to the Sun than Uranus.

Answer explanation

Neptune is the farthest planet from the Sun in our solar system, located beyond Uranus. Therefore, the correct choice is that it is the farthest from the Sun.

Which of the following statements is true about the atmospheres of the outer planets?

• They are mostly composed of carbon dioxide.

• They have thick atmospheres with high pressure.

• They lack any form of atmosphere.

• They have thin atmospheres with low pressure.

Answer explanation

The outer planets, such as Jupiter and Saturn, have thick atmospheres primarily composed of hydrogen and helium, resulting in high pressure. This distinguishes them from terrestrial planets, which have thinner atmospheres.

Compare the size of Pluto to the other outer planets.

• Pluto is larger than Neptune.

• Pluto is smaller than all the outer planets.

• Pluto is the same size as Uranus.

• Pluto is larger than Saturn.

Answer explanation

Pluto is classified as a dwarf planet and is significantly smaller than the outer planets: Jupiter, Saturn, Uranus, and Neptune. Therefore, the correct choice is that Pluto is smaller than all the outer planets.

Which outer planet is known for having a Great Red Spot, a giant storm?

• Saturn

• Uranus

• Neptune

• Jupiter

Answer explanation

Jupiter is known for its Great Red Spot, a massive storm that has been raging for centuries. The other outer planets, Saturn, Uranus, and Neptune, do not have a storm of this magnitude.