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

Staff Writer

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

Which "dwarf planet" is no longer considered part of the main group in our solar system?

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.

Officially, how many planets are there in our solar system?

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.

Which of these is part of the criteria to be considered a planet in our solar system?

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.

Which of these planets was not named after a Roman or Greek god?

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

What is the biggest planet in our solar system?

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.

What is the smallest planet in our solar system?

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

Which of these is not considered to be a gas planet?

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

Which of these planets is considered a terrestrial planet?

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.

What is the correct order of the planets?

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.)

Which planet is the largest of the terrestrial planets?

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

What planet in our solar system is often called the "Red Planet"?

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.

Which planet has the shortest days of all the planets?

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

The Great Red Spot is a feature on which planet?

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.

Which of these planets does not have a ring around it?

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

This planet has the largest moon in the solar system, Ganymede.

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

Which planet holds the title as the densest in our solar system?

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

Which planet experiences the highest temperatures of any planet?

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.

Which planet has the shortest year?

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

Which planet takes the longest to make one rotation on its axis?

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.

Which planet features Titan as one of its moons?

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.

Which planet is considered an "ice giant"?

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

Which of these planets doesn't have any moons?

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.

Which planet has the coldest average temperature in the solar system?

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.

Which planet is often considered Earth's sister planet?

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.

Which planet is the smaller of the two "ice giants"?

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

The Great Dark Spot was a feature on which planet?

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.

Which planet has the most moons of any in the solar system?

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

Also known as Planet Nine, what hypothetical body is believed to exist beyond Pluto?

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.

Which is the brightest planet in our solar system?

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.

Which planet's axis is at a 98-degree angle, which means it rotates on its side?

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

Which planet is home to Olympus Mons, the largest of all known volcanoes in the solar system?

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.

Including Pluto, how many dwarf planets exist in our solar system?

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

Which planet is known for its severe dust storms?

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.

Which is the only planet known to be less dense than water?

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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