The Outer Planets / Study Guide

The Outer Planets / Study Guide

The four outer planets are Jupiter, Saturn, Uranus, and Neptune. They are also known as the gas giants because they are large and composed of mostly helium and hydrogen. However, the materials inside of the outer planets is actually liquid due to the high pressure levels inside of the planets. The outer layers of the planets are extremely cold because the planets are so far from the Sun.

All of the outer planets are much larger and more massive than the inner planets. Neptune is the smallest of the outer planets, but it still has a volume that is almost 60 times greater than Earth's.

All four of the outer planets are surrounded by a set of rings. The rings are made of rock, ice, and dust. Saturn's are the largest and most defined of the four outer planets. The outer planets also all have several more moons than the inner planets. Neptune as at least 13 moons, while Jupiter has over 60 moons.

Multiple Choice

Use the chart at left (click to enlarge) to determine what determines a planets period of revolution (how long it takes to revolve around the sun).

• As a planet's diameter increases, its period of rotation increases

• As a planet's average distance from the Sun increases, its period of revolution increases.

• As a planet's diameter increases, its period of revolution decreases.

• As a planet's period of rotation increases, its period of revolution decreases.

Multiple Select

Which of the following characteristics are featured in the outer planets. Select all that apply.

• hotter

• bigger

• rocky surfaces

• more moons

• colder

Jupiter

The largest planet in the solar system, over 1,321 Earths could fit inside of Jupiter! It has the largest mass and gravity of all the planets. Jupiter has a thick hydrogen and helium. Some hypothesize that Jupiter may have a solid core of metal and rock  surrounded by a large layer of liquid metallic hydrogen. Like the other gas giants, Jupiter has extremely cold temps. It's average temp is -150 degrees

There is a massive storm on Jupiter called the Great Red Spot. The swirling winds of the storm are similar to those of a hurricane on Earth. Astronomers have observed the storm for over 350 years, and there are no signs that the storm will go away anytime soon.

Jupiter has the most moons of any planet. There are over 60 moons that orbit Jupiter. Jupiter has four particularly large moons, which are named Io, Europa, Ganymede, and Callisto. Ganymede is larger than the planet Mercury. Scientists believe that Jupiter's moon Io is volcanically active.

Multiple Select

Which of these words or phrases correctly describe Jupiter?

• most extreme temperatures

• farthest from the Sun

• has the most moons

• most massive planet

Multiple Choice

If Jupiter's moon Ganymeade is larger than the planet Mercury, why is it not considered a planet?

• Ganymeade is made of ice and not rock.

• Ganymeade is too far from the Sun.

• Ganymede was discovered too late.

• Ganymeade orbits a planet and not the Sun.

Saturn

Saturn is the second largest planet in the solar system. Like Jupiter, Saturn is an extremely massive planet, as its mass is 95 times greater than the mass of earth. Around 763 Earths could fit inside of Saturn.

Scientists believe that Saturn has a solid core made of rock and metal that is surrounded by a layer of liquid metallic hydrogen. While Saturn is one of the largest planets, it has the lowest density of any planet in the solar system. Its density is less than that of water!

Saturn has the most defined ring system of any planet in the solar system. The rings that orbit Saturn are made of chunks of ice and rock. The chunks of ice and rock range in size from a few millimeters to several hundred meters in size. The rings each orbit individually, but they form larger, more complex bands. Between each of the bands is a gap that may be occupied by one of Saturn's many moons.

There are 53 named moons orbiting Saturn. There are also many more, smaller moons, called moonlets, among Saturn's rings. Titan, Saturn's largest moon, is larger than the planet Mercury. It has a thick atmosphere composed of nitrogen and methane. Titan is the only moon in the solar system with a thick atmosphere.

Scientists believe that one of Saturn's moons, Enceladus, holds liquid water underneath its surface. NASA's Cassini spacecraft discovered geysers that release water vapor on the surface of Enceladus. Scientists are now gathering evidence that points toward the existence of an ocean of liquid water underneath the surface of this moon. Some scientists even think there might be microbial life on Enceladus.

Multiple Choice

Saturn's rings are made up of ice and rock.

Multiple Choice

Saturn's rings do not move.

Multiple Choice

Saturn's density is less than the density of water.

Multiple Choice

Saturn is the _______ largest planet in our solar system.

• second

• third

• fourth

• fifth

• sixth

Multiple Choice

Saturn is made up of mostly helium and ________.

• hydrogen

• methane

• nitrogen

Multiple Choice

Saturn has a large and defined _______.

• Great Red Spot

• ocean system

• ring system

Multiple Choice

Saturn has over ______ moons in orbit.

• 100

• 200

• 10

• 50

Multiple Select

Which of the following statements about Saturn's moons are true? Check all that are correct.

• Saturn's moon Titan is the only moon in the solar system with a thick atmosphere.

• There are many small moons located in the gaps of Saturn's rings.

• Scientists have found evidence which indicates that Saturn's moon Enceladus holds liquid water underneat its surface.

• Saturn's moon Titan is larger than the planet Mercury.

Uranus

Uranus is the seventh planet from the Sun. It has about 15 times the mass of Earth and 63 times the diameter. However, it is still significantly smaller than Jupiter and Saturn. Uranus has at least 27 moons in its orbit. It also has a group of thin, flat rings in its orbit. However, these rings are less prominent, and much darker, than Saturn's. Uranus looks blue-green because of the methane int its atmosphere.

Uranus has a unique axis of rotation, as it is tilted about 98 degrees. The rings and moons of Uranus still orbit its equator. Therefore, when Uranus is viewed from the Earth, it appears as though it rotates from top to bottom instead of from side to side like the other planets.

Astronomers think that billions of years ago something may have hit Uranus that was powerful enough to knock it on its side. Other theories state that the powerful gravities of Saturn and Jupiter may have caused the orbit of Uranus to change.

Of Uranus's 27 moons, its five largest have icy, cratered surfaces.

Multiple Choice

Click on the angle that is most similar to Uranus's axis.

Neptune

Neptune is the farthest planet from the Sun. Neptune has about 58 times the volume of Earth. It is also the coldest planet, with an average surface temperature of -220 degrees Celsius. Sunlight on Neptune is 900 times fainter than sunlight on Earth.

Neptune is the smallest of the outer planets and just slightly smaller than Uranus. Similar to Uranus, Neptune has an atmosphere of helium and hydrogen with some methane. The methane gives Neptune its deep blue color. Its interior is made up of liquid hydrogen, helium, and methane ice. Neptune's atmosphere also contains visible clouds.

Neptune has the strongest winds of any planet. The wind speeds can reach up to 2,000 km/h. These winds are caued by Neptune's warm interior, which produces more energy than the planet receives from sunlight. In 1989, NASA's space probe Voyager 2 passed by Neptune and photographed a large dark area on the planet that was about the size of Earth. Named the great Dark Spot, scientists concluded that it was probably a giant storm, similar to the Great Red Spot on Jupiter.

Neptune has 13 moons compared to Uranus's 27. Triton is Neptune's largest moon. Unlike most moons, Triton orbits Neptune in the opposite direction of Neptune's rotation. Triton has a thin atmosphere that is composed of mostly nitrogen and some methane. There is also volcanic activity on Triton's surface. However, the volcanoes do not erupt liquid rock like on Earth. The lava has an icy mixture of water and ammonia.

Multiple Select

Which of these phrases describe Neptune? Check all that are true.

• strongest winds of any planet

• second largest planet

• farthest from the Sun

• coldest planet

Multiple Choice

The ______ in Neptune's atmosphere gives it a deep blue color.

• water

• helium

• hydrogen

• methane

• ice

Multiple Choice

_____ is the largest outer planet, and ______ is the smallest.

• Saturn; Uranus

• Jupiter; Neptune

• Neptune; Jupiter

• Neptune; Saturn

Multiple Choice

Use the table at left (click to enlarge) to answer the following question: What is the density of Saturn?

Hint: The density of earth is 1.0

• 0.687

• 1.99

• 4.67

• 6.56

Multiple Select

Which of the following planets have rings composed of rock, ice, and dust? Check all that apply.

• Neptune

• Uranus

• Saturn

• Jupiter

Multiple Choice

______ is the largest planet in the solar system.

• Jupiter

• Neptune

• Saturn

• Mars

• Venus

Multiple Choice

______ has the strongest winds in the solar system.

• Jupiter

• Neptune

• Saturn

• Mars

• Venus

Multiple Choice

______ has the largest and most prominent ring system of all the planets.

• Jupiter

• Neptune

• Saturn

• Mars

• Venus

Multiple Choice

______ is tilted on its side as it orbits the Sun.

• Jupiter

• Neptune

• Saturn

• Mars

• Uranus

Multiple Select

Which of the following sentences correctly describe Jupiter? Check all that are true.

• There is a massive, hurricane-like storm on its surface.

• it has rings composed of rock, ice, and dust in its orbit.

• It is the largest planet in the solar system.

• its surface is composed of volcanic rock and red dust.

Multiple Choice

Which characteristic is true of all of the outer planets?

• They have thin atmospheres.

• They have rocky surfaces.

• They have several moons.

• They are move massive than the Sun.

Multiple Choice

Saturn is the second most massive planet, but it is also the ______ planet.

• least dense

• coldest

• hottest

• windiest

Multiple Choice

Which planet is pictured at left?

• Neptune

• Saturn

• Jupiter

• Uranus

Multiple Choice

Travis writes a description of Neptune (at left) for science class. Which of the following statements corrects Travis's description

• Neptune is not the farthest planet from the Sun.

• Neptune's Great Dark Spot no longer exists.

• Neptune is not the windiest planet.

• Neptune does not have 14 moons. It has 60.

Multiple Choice

Travis writes a description of Neptune (at left) for science class. Which of the following statements corrects Travis's description

• Neptune is not the farthest planet from the Sun.

• Neptune's Great Dark Spot no longer exists.

• Neptune is not the windiest planet.

• Neptune does not have 14 moons. It has 60.