Solar System Quiz: Planets, Moons, Pluto and the Sun

This solar system quiz tours our cosmic neighborhood, from Mercury and the Sun to Jupiter, Mars, Uranus, dwarf planet Pluto, Saturn's many moons, Olympus Mons and the asteroid belt. Ten questions, 90 seconds, and every answer explained.

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🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 90 Seconds

Question 1 / 10 Time: 90s

Planets
Which planet is closest to the Sun?
Planets
Which is the largest planet in the solar system?
Planets
Which planet is known as the Red Planet?
Basics
How many planets are in our solar system?
Planets
Which planet rotates on its side, with an axis tilted about 98 degrees?
Pluto
In which year was Pluto reclassified as a dwarf planet?
Moons
Which planet has the most known moons?
The Sun
About how long does sunlight take to reach Earth?
Geology
What is the largest known volcano in the solar system?
Structure
What lies between the orbits of Mars and Jupiter?

Explanations: answer key for all 10 questions

Q1: Which planet is closest to the Sun?
Answer: Mercury
Mercury orbits the Sun in just 88 Earth days. Despite being closest, it is not the hottest planet; Venus is hotter because its thick atmosphere traps heat.
Q2: Which is the largest planet in the solar system?
Answer: Jupiter
Jupiter is more than twice as massive as all the other planets combined, and about 1,300 Earths could fit inside it. Its Great Red Spot is a storm larger than Earth.
Q3: Which planet is known as the Red Planet?
Answer: Mars
Mars looks red because iron minerals in its soil have rusted. NASA's Perseverance rover has been exploring Jezero Crater since 2021.
Q4: How many planets are in our solar system?
Answer: 8
The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto was counted as the ninth until 2006.
Q5: Which planet rotates on its side, with an axis tilted about 98 degrees?
Answer: Uranus
Scientists think a huge collision long ago knocked Uranus onto its side. As a result, each pole gets about 42 years of continuous sunlight followed by 42 years of darkness.
Q6: In which year was Pluto reclassified as a dwarf planet?
Answer: 2006
The International Astronomical Union created the dwarf planet category in 2006. NASA's New Horizons spacecraft flew past Pluto in 2015 and found a heart-shaped plain of nitrogen ice.
Q7: Which planet has the most known moons?
Answer: Saturn
Saturn has more than 270 officially recognized moons, far more than any other planet. Its largest moon, Titan, has a thick atmosphere and lakes of liquid methane.
Q8: About how long does sunlight take to reach Earth?
Answer: 8 minutes
Sunlight travels about 150 million kilometers to reach Earth in roughly 8 minutes and 20 seconds. That means we always see the Sun as it was a few minutes ago.
Q9: What is the largest known volcano in the solar system?
Answer: Olympus Mons
Olympus Mons on Mars stands about 22 kilometers high, around two and a half times the height of Mount Everest. Its base is about 600 kilometers wide, roughly the size of Poland.
Q10: What lies between the orbits of Mars and Jupiter?
Answer: Asteroid belt
The asteroid belt holds millions of rocky bodies, including the dwarf planet Ceres. The Kuiper Belt, home to Pluto, lies far beyond Neptune.

Solar System Quiz – A Tour of Our Cosmic Neighborhood

Our solar system formed about 4.6 billion years ago from a giant cloud of gas and dust. At its center is the Sun, a star that holds more than 99.8 percent of all the mass in the system. Around it travel eight planets, five officially recognized dwarf planets, hundreds of moons and countless asteroids and comets.

The four inner planets, Mercury, Venus, Earth and Mars, are small and rocky. Beyond the asteroid belt lie the giants: Jupiter and Saturn, made mostly of hydrogen and helium, and the ice giants Uranus and Neptune. Each planet has its own personality, from Venus's crushing, acid-cloud atmosphere to Uranus's strange sideways spin.

Moons are among the most exciting places to explore. Jupiter's Europa and Saturn's Enceladus hide oceans beneath their icy crusts, which makes them some of the best places to search for life beyond Earth. Saturn's Titan even has rivers and lakes, although they are made of liquid methane rather than water.

Our understanding of the solar system keeps changing. Pluto was demoted to a dwarf planet in 2006, new moons are discovered almost every year and spacecraft such as Juno, Perseverance and New Horizons continue to send back new pictures and data.

This quiz tests the essentials of our cosmic neighborhood, with an explanation for each answer to help you remember it.

What This Quiz Teaches

This quiz suits students, stargazers and anyone who wants to know more about the planets.

The order and size of the planets
Why Mars is red and Uranus spins on its side
When and why Pluto became a dwarf planet
Which planet has the most moons
How long sunlight takes to reach Earth
Where the asteroid belt is and what it holds

Quick Facts About the Solar System

A day on Venus is longer than its year.
Saturn's density is so low that it would float in a giant bathtub of water.
Neptune has the fastest winds in the solar system, over 2,000 km/h.
Earth is the only planet not named after a Greek or Roman god.
The Moon is slowly moving away from Earth by about 3.8 cm a year.
Jupiter's moon Ganymede is bigger than the planet Mercury.