Solar System & Space
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40 free Solar System & Space trivia questions with answers — science & nature quiz, new questions added Aug 2026.
Did you know that a day on Venus is longer than its year? Test your cosmic knowledge with our comprehensive 40-question Solar System & Space quiz. You'll explore everything from distant galaxies to the planets orbiting our Sun, uncovering mind-bending facts about the universe.
30 of 40 questions with answers and explanations. Play the quiz
Q 01Which planet is known as the Red Planet?
Mars
Mars is the Red Planet: its colour comes from dust and sand rich in reddish iron oxides, essentially rust, spread across its plains.
Q 02How many planets are in our solar system?
8
The count fell from nine to eight when Pluto was reclassified as a dwarf planet in 2006.
Q 03Which planet is closest to the Sun?
Mercury
Mercury is the closest planet to the Sun, orbiting at an average distance of about 57.9 million kilometers.
Q 04Who was the first human to travel to space?
Yuri Gagarin
Yuri Gagarin ejected from Vostok 1 about 7 km above the ground and parachuted down separately from his capsule.
Q 05Which Apollo mission first landed astronauts on the Moon?
Apollo 11
Neil Armstrong partly piloted Apollo 11's lunar module by hand to find a safe place to set it down.
Q 06What is the hottest planet in our solar system?
Venus
Venus is only the second planet from the Sun, yet its thick carbon dioxide atmosphere traps so much heat that its surface tops 460°C.
Q 07What is the asteroid belt located between?
Mars and Jupiter
The gravity of newly formed Jupiter stirred up the rocks between Mars and Jupiter, so they smashed together instead of building a planet.
Q 08Which NASA rover landed on Mars in February 2021 to search for signs of ancient life?
Perseverance
Perseverance landed in Jezero Crater, once a lake with a river delta, and has been sealing rock cores in tubes that a future mission could bring to Earth.
Q 09What is the primary composition of the Sun?
Hydrogen and helium
The Sun is mostly hydrogen and helium, and its core fuses hydrogen into helium, releasing the energy that makes it shine.
Q 10Who was the first American woman in space?
Sally Ride
Sally Ride kept her 27-year relationship with Tam O'Shaughnessy private, and it became public only in her obituary in 2012.
Q 11Which space telescope, launched in 2021, primarily observes in infrared wavelengths?
James Webb Space Telescope
The James Webb Space Telescope must stay extremely cold so its own heat doesn't drown out faint infrared light, so a five-layer sunshield keeps it in shade.
Q 12Which craft made the first powered, controlled flight on another planet?
Ingenuity
Ingenuity was built to make just five test flights, but it flew 72 times over nearly three years.
Q 13What is the Great Red Spot?
A giant storm
The Great Red Spot is a giant storm wider than Earth, and NASA's Juno spacecraft flew over it in July 2017, photographing its tangled clouds.
Q 21Approximately how far is one light-year?
9.46 trillion kilometers
One light-year is about 9.46 trillion kilometers, so light from Proxima Centauri, the nearest star after the Sun, takes over four years to reach us.
Q 22Which spacecraft became the first to enter interstellar space?
Voyager 1
Voyager 1 launched in 1977 to fly past Jupiter and Saturn, and as of 2026 it was still sending data home from interstellar space.
Q 23Which planet could theoretically float in water due to its low density?
Saturn
Saturn's rapid spin makes it bulge, so its equatorial radius is more than 10% longer than its polar radius.
Q 14Who is credited with discovering the four largest moons of the biggest planet in 1610?
Galileo Galilei
Galileo Galilei gets the credit, though Simon Marius spotted the same four moons at about the same time, and his names for them stuck.
Q 15What is the tallest volcano in the solar system?
Olympus Mons
Olympus Mons likely grew so tall because the crust beneath it stayed over one hot spot, so lava kept piling up in the same place.
Q 16What are the rings of the second-largest planet made almost entirely of?
Water ice
The rings are almost pure water ice, and that bright, clean ice is one clue that they may be much younger than the planet itself.
Q 17What region of the solar system lies beyond Neptune's orbit and contains Pluto?
Kuiper Belt
Pluto, found in 1930, was the first Kuiper Belt object ever discovered, spotted before astronomers had any reason to expect such a belt.
Q 18What does one astronomical unit (AU) represent?
The distance from the Sun to Earth
The AU began as the distance from the Sun to Earth, but relativity made its old definition too complicated, so in 2012 the IAU fixed it at an exact number of metres.
Q 19Which NASA mission flew past Pluto in 2015, providing the first close-up images?
New Horizons
New Horizons carried some of Clyde Tombaugh's ashes, so the astronomer who discovered Pluto made the journey there too.
Q 20What is the largest moon in our solar system?
Ganymede
Ganymede makes its own magnetic field, which lights up auroras around its poles, and it likely hides an underground saltwater ocean.
Q 24What did Neil Armstrong and Buzz Aldrin name their landing site on the Moon?
Tranquility Base
After touching down, Neil Armstrong radioed, 'Houston, Tranquility Base here. The Eagle has landed.'
Q 25Which planet is tilted almost on its side, with an axial tilt of about 98 degrees?
Uranus
Uranus rolls around the Sun almost on its side, so each pole spends decades in continuous sunlight and then decades in darkness.
Q 26Which moon of Saturn has liquid methane lakes on its surface?
Titan
Titan's methane falls as rain, carving rivers and filling lakes in a cycle much like the water cycle on our own planet.
Q 27Which dwarf planet is the only confirmed one inside the main asteroid belt?
Ceres
Ceres's mysterious bright spots, seen up close by NASA's Dawn, turned out to be salt deposits left by briny water seeping up from below.
Q 28Which moon in our solar system is the most volcanically active body?
Io
Io has hundreds of active volcanoes, heated by a tug-of-war between Jupiter's gravity and the pulls of its neighbouring moons.
Q 29What message for aliens does each Voyager probe carry?
Record
Each Voyager carries a golden record whose contents a committee chaired by Carl Sagan chose, while the earlier Pioneer probes carried plaques.
Q 30Which planet has the fastest winds in the solar system?
Neptune
Neptune's winds reach about 2,000 km/h despite the planet's great distance and the weak sunlight it receives.