Astronomy: Planets Worksheet

Question 1

List the eight planets in order from closest to the Sun to farthest from the Sun.

Accepted Answer

The eight planets in order from closest to the Sun to farthest from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Question 2

Which planets are called the terrestrial planets, and what do they have in common?

Accepted Answer

Mercury, Venus, Earth, and Mars are called the terrestrial planets. They have solid rocky surfaces and are located in the inner solar system.

Question 3

Which planets are called the gas giants, and why are they described that way?

Accepted Answer

Jupiter and Saturn are called gas giants because they are very large planets made mostly of hydrogen and helium, with no solid surface like Earth has.

Question 4

Uranus and Neptune are often called ice giants. How are ice giants different from gas giants?

Accepted Answer

Uranus and Neptune are called ice giants because they contain larger amounts of icy materials such as water, ammonia, and methane compared with Jupiter and Saturn. They are also smaller than the gas giants.

Question 5

A year on a planet is the time it takes to orbit the Sun once. Which planet has a shorter year, Mercury or Mars? Explain why.

Accepted Answer

Mercury has a shorter year than Mars because Mercury is closer to the Sun and travels a smaller orbit. Planets closer to the Sun usually complete their orbits faster.

Question 6

A day on a planet is related to how long it takes the planet to rotate once on its axis. Earth rotates once in about 24 hours. What does rotation mean in astronomy?

Accepted Answer

Rotation means the spinning motion of a planet on its axis. One complete rotation is one day for that planet.

Question 7

What is revolution in astronomy, and how is it different from rotation?

Accepted Answer

Revolution is the motion of a planet traveling around the Sun. Rotation is a planet spinning on its own axis, while revolution is a planet moving in an orbit around another object.

Question 8

Venus is hotter than Mercury even though Mercury is closer to the Sun. Explain one reason for this.

Accepted Answer

Venus is hotter than Mercury because Venus has a thick atmosphere with a strong greenhouse effect. The atmosphere traps heat and keeps the planet extremely hot.

Question 9

Jupiter has a Great Red Spot. What is the Great Red Spot?

Accepted Answer

The Great Red Spot is a huge storm in Jupiter's atmosphere. It has lasted for hundreds of years and is much larger than storms on Earth.

Question 10

Saturn is famous for its rings. What are Saturn's rings mostly made of?

Accepted Answer

Saturn's rings are mostly made of pieces of ice and rock. The particles range in size from tiny grains to much larger chunks.

Question 11

Why is Pluto classified as a dwarf planet instead of one of the eight major planets?

Accepted Answer

Pluto is classified as a dwarf planet because it orbits the Sun and is round, but it has not cleared its orbital path of other objects. This is one of the requirements for being classified as a major planet.

Question 12

Choose the planet that best fits this description: It is known as the Red Planet and has evidence of ancient water on its surface. Explain your choice.

Accepted Answer

The planet is Mars. Mars is called the Red Planet because iron-rich minerals on its surface give it a reddish color, and scientists have found evidence that liquid water once flowed there.

Question 13

The inner planets are smaller and rocky, while the outer planets are larger and made mostly of gases or ices. What separates these two groups of planets in the solar system?

Accepted Answer

The asteroid belt separates the inner planets from the outer planets. It is located between the orbits of Mars and Jupiter.

Question 14

A student says, "The biggest planet must also be the farthest from the Sun." Is the student correct? Use examples to support your answer.

Accepted Answer

The student is not correct. Jupiter is the biggest planet, but Neptune is the farthest planet from the Sun. Planet size and distance from the Sun are different properties.

Question 15

Describe two ways Earth is suitable for life compared with many other planets in the solar system.

Accepted Answer

Earth is suitable for life because it has liquid water on its surface and an atmosphere that helps keep temperatures in a livable range. Earth also has oxygen and protection from some harmful solar radiation.

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Astronomy: Planets

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