How well do you know the planets in our solar system?

Estimated Completion Time
3 min
How well do you know the planets in our solar system?
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About This Quiz

The cosmos is an expansive, complicated place that often inspires more questions than answers. There is still a lot we do know about the planets in our own solar system, but just how much do you know? Find out what you know about our cosmic neighborhood with this quiz!
What is the only planet in our solar system known to support life?
Earth
Mars
Saturn
Venus
Correct Answer
Wrong Answer

Earth is called the "Goldilocks Planet," meaning it is in the sun's habitable zone. The search continues to find another like it.

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Which "dwarf planet" is no longer considered part of the main group in our solar system?
Uranus
Neptune
Pluto
Planet-X
Correct Answer
Wrong Answer

In 2006, Pluto was officially demoted from the traditional list of planets in our solar system by the IAU (International Astronomical Union), a body that is responsible for naming and classifying objects in space.

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Officially, how many planets are there in our solar system?
six
seven
eight
nine
Correct Answer
Wrong Answer

Pluto, now considered a "dwarf planet," lost its planetary status because it has not "cleared the neighborhood" around its orbit, one of the three criteria for a body to be considered a planet.

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Which of these is part of the criteria to be considered a planet in our solar system?
The body is in orbit around the sun.
The body has sufficient mass to assume hydrostatic equilibrium - a nearly round shape.
The body has "cleared the neighborhood" around its orbit.
All of the above.
Correct Answer
Wrong Answer

In order to be considered a planet, bodies in the solar system must meet all three of these standards. Pluto didn't meet the third criteria; therefore, it is no longer considered to be a planet.

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Which of these planets was not named after a Roman or Greek god?
Neptune
Jupiter
Mars
Earth
Correct Answer
Wrong Answer

Earth is the only planet not to be named after a Roman or Greek god - just another reason why our planet is special.

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What is the biggest planet in our solar system?
Jupiter
Saturn
Earth
Neptune
Correct Answer
Wrong Answer

Jupiter beats every planet in both mass and volume. In fact, it is over two times more massive than the rest of the planets in the solar system combined.

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What is the smallest planet in our solar system?
Venus
Mercury
Mars
Neptune
Correct Answer
Wrong Answer

Mercury's diameter is 0.38 times that of Earth. The tiny planet is closer in size to Earth's moon than Earth itself.

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Which of these is not considered to be a gas planet?
Jupiter
Uranus
Neptune
Venus
Correct Answer
Wrong Answer

Saturn is the sixth planet from the sun. Uranus, Neptune, Jupiter and Saturn are the gas giants of our solar system.

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Which of these planets is considered a terrestrial planet?
Earth
Mars
Mercury
all of the above
Correct Answer
Wrong Answer

Venus is the other terrestrial planet in our solar system. While the closest four planets are all considered terrestrial, the furthest four planets are all gas giants.

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What is the correct order of the planets?
Venus, Mercury, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Neptune, Mercury, Venus, Mars, Earth, Jupiter, Saturn, Uranus
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
none of the above
Correct Answer
Wrong Answer

Perhaps you remember Screech from "Saved by the Bell" and his way to remember the planets in order: MVEMJSUNP. (Of course, the "P" for Pluto is no longer needed.)

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Which planet is the largest of the terrestrial planets?
Mercury
Earth
Venus
Mars
Correct Answer
Wrong Answer

Earth's diameter is about 600 km more than that of Venus. The other two are quite a bit smaller.

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What planet in our solar system is often called the "Red Planet"?
Jupiter
Saturn
Mercury
Mars
Correct Answer
Wrong Answer

Mars has become well known for its red color. This hue is the result of the planet's surface, which includes a lot of iron oxide.

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Which planet has the shortest days of all the planets?
Saturn
Jupiter
Earth
Mercury
Correct Answer
Wrong Answer

Despite its massive size, Jupiter rotates faster on its axis than any other planet. Its average day is 9 hours and 55 minutes.

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The Great Red Spot is a feature on which planet?
Mars
Mercury
Saturn
Jupiter
Correct Answer
Wrong Answer

The Great Red Spot is a massive storm that has been going on for at least 150 years, and quite possibly much longer than that. The storm is twice as wide as Earth.

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Which of these planets does not have a ring around it?
Venus
Uranus
Saturn
Neptune
Correct Answer
Wrong Answer

Jupiter, Saturn, Uranus and Neptune all have rings. These four planets are all gas giants as well.

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This planet has the largest moon in the solar system, Ganymede.
Saturn
Jupiter
Earth
Uranus
Correct Answer
Wrong Answer

One of Jupiter's moons, Ganymede, takes the crown as the largest in our solar system. It is bigger than Mercury.

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Which planet holds the title as the densest in our solar system?
Jupiter
Mercury
Saturn
Earth
Correct Answer
Wrong Answer

We live on the densest planet around. Despite its small size, Mercury comes in second.

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Which planet experiences the highest temperatures of any planet?
Mars
Venus
Mercury
Saturn
Correct Answer
Wrong Answer

Even though it is closest to the Sun, Mercury is not the hottest planet. Venus averages a temperature of about 462 degrees Celsius, and it does not drop off like Mercury does on the side not facing the sun.

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Which planet has the shortest year?
Neptune
Mercury
Earth
Mars
Correct Answer
Wrong Answer

One year on Mercury lasts 88 Earth days. This is because Mercury has the shortest orbit around the sun.

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Which planet takes the longest to make one rotation on its axis?
Mars
Saturn
Venus
Uranus
Correct Answer
Wrong Answer

One day on Venus is about 5,832 hours - or 243 Earth days. The planet takes longer to rotate on its axis than it does to orbit the sun.

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Which planet features Titan as one of its moons?
Jupiter
Uranus
Saturn
Neptune
Correct Answer
Wrong Answer

Titan is Saturn's largest and most famous moon. It is composed mostly of water, ice, and rock, and scientists believe it could hold life.

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Which planet is considered an "ice giant"?
Uranus
Mars
Venus
Saturn
Correct Answer
Wrong Answer

Uranus and Neptune are the ice giants of our solar system. They are also the furthest two planets from the sun.

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Which of these planets doesn't have any moons?
Earth
Neptune
Mercury
Saturn
Correct Answer
Wrong Answer

The smallest planet in our solar system, Mercury, has no moons or ring to speak of. Poor Mercury. Venus doesn't have a moon either.

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Which planet has the coldest average temperature in the solar system?
Neptune
Uranus
Saturn
Jupiter
Correct Answer
Wrong Answer

While Neptune has the coldest average temperatures, it is Uranus that can reach a colder temperature than the furthest planet from the sun. Go figure.

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Which planet is often considered Earth's sister planet?
Venus
Mars
Mercury
none of the above
Correct Answer
Wrong Answer

Venus is the closest in size to Earth, thus its title as a sister planet. Earth's diameter is just 642 km bigger than that of Venus.

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Which planet is the smaller of the two "ice giants"?
Uranus
Earth
Neptune
Saturn
Correct Answer
Wrong Answer

Neptune does have a greater mass than Uranus, but is still smaller in size.

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The Great Dark Spot was a feature on which planet?
Neptune
Uranus
Jupiter
Saturn
Correct Answer
Wrong Answer

The Great Dark Spot was a storm that raged on Neptune, with winds measured at 1,500 miles per hour, the strongest winds ever recorded on any planet in the solar system. It was first seen in 1989, and it was gone by 1994.

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Which planet has the most moons of any in the solar system?
Mars
Uranus
Jupiter
Saturn
Correct Answer
Wrong Answer

As of 2009, Jupiter has 63 confirmed moons. It also has the biggest moon in the solar system, Ganymede.

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Also known as Planet Nine, what hypothetical body is believed to exist beyond Pluto?
Planet W
Planet Z
Planet Y
Planet X
Correct Answer
Wrong Answer

The hypothetical planet has even led to doomsday conspiracy theories from some. It is believed one orbit around the sun could take between 10,000 and 20,000 years - if the planet exists at all.

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Which is the brightest planet in our solar system?
Neptune
Earth
Venus
Mercury
Correct Answer
Wrong Answer

Because of its yellow clouds of sulfuric acid, Venus reflects the sun's light enough to be the brightest planet in the solar system. It can be seen from Earth with the naked eye.

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Which planet's axis is at a 98-degree angle, which means it rotates on its side?
Mercury
Jupiter
Neptune
Uranus
Correct Answer
Wrong Answer

To compare, Earth's axis is at a 23-degree angle. All of Uranus' moons mimic the way it spins on its axis.

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Which planet is home to Olympus Mons, the largest of all known volcanoes in the solar system?
Earth
Jupiter
Mars
Venus
Correct Answer
Wrong Answer

Olympus Mons is approximately the same size as the state of Arizona. It also has a volume over 100 times larger than that of the largest volcano on Earth, Mauna Loa.

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Including Pluto, how many dwarf planets exist in our solar system?
zero
one
five
nine
Correct Answer
Wrong Answer

Pluto, Ceres, Eris, Haumea and Makemake are the five dwarf planets. Pluto joined the other four back in 2006.

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Which planet is known for its severe dust storms?
Saturn
Mars
Jupiter
Neptune
Correct Answer
Wrong Answer

Some of Mars' dust storms can be the size of continents on Earth and last for weeks at a time. About once every three years Mars experiences a dust storm that covers the planet, known as a global dust storm.

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Which is the only planet known to be less dense than water?
Uranus
Neptune
Jupiter
Saturn
Correct Answer
Wrong Answer

If you were able to find a body of water large enough to fit Saturn, the planet would float. This is despite the fact that it is the second-largest planet in the solar system.

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