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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
Soviet cosmonaut Yuri Gagarin became the first human in space on April 12, 1961, completing one orbit of Earth aboard the Vostok 1 spacecraft in a flight lasting 108 minutes.
Q 05In what year did Apollo 11 land humans on the Moon for the first time?
1969
Apollo 11 landed on the Moon on July 20, 1969. Neil Armstrong became the first person to step onto the lunar surface, followed by Buzz Aldrin 19 minutes later.
Q 06What is the hottest planet in our solar system?
Venus
Despite being farther from the Sun than Mercury, Venus is the hottest planet due to its thick atmosphere of carbon dioxide, which traps heat in a runaway greenhouse effect, pushing surface temperatures above 460°C.
Q 07What is the asteroid belt located between?
Mars and Jupiter
The asteroid belt is located between the orbits of Mars and Jupiter, roughly 2.2 to 3.2 AU from the Sun. It contains millions of rocky objects believed to be remnants from the early solar system.
Q 08Which NASA rover landed on Mars in February 2021 to search for signs of ancient life?
Perseverance
Perseverance landed in Jezero Crater on 18 February 2021 and found evidence of an ancient lake and river delta, caching rock cores for a planned sample return to Earth.
Q 09What is the primary composition of the Sun?
Hydrogen and helium
By mass the Sun is roughly 73% hydrogen and 25% helium, with only traces of heavier elements such as oxygen, carbon, neon and iron.
Q 10Who was the first American woman in space?
Sally Ride
Sally Ride became the first American woman in space on June 18, 1983, aboard the Space Shuttle Challenger during the STS-7 mission.
Q 11Which space telescope, launched in 2021, primarily observes in infrared wavelengths?
James Webb Space Telescope
The James Webb Space Telescope (JWST), launched December 25, 2021, observes in infrared wavelengths (0.6-28.5 micrometers). Its 6.5-meter gold-plated mirror gives it six times the light-collecting area of Hubble.
Q 12What small helicopter made the first powered, controlled flight on another planet?
Ingenuity
NASA's Ingenuity helicopter made the first powered, controlled flight on another planet on 19 April 2021, rising about 3 metres above Jezero Crater on Mars, and completed 72 flights before its mission ended in January 2024.
Q 13What is the Great Red Spot?
Q 21Approximately how far is one light-year?
9.46 trillion kilometers
A light-year is approximately 9.46 trillion kilometers (5.88 trillion miles) — the distance that light travels in one Earth year at a speed of about 300,000 km per second.
Q 22Which spacecraft became the first to enter interstellar space?
Voyager 1
Voyager 1 crossed into interstellar space on 25 August 2012, about 121 AU from the Sun, and is the most distant human-made object; Voyager 2 followed in November 2018.
Q 23Which planet could theoretically float in water due to its low density?
Saturn
Saturn's average density is about 0.69 g/cm³, roughly 30% less than water, so in an imaginary ocean big enough it would bob on the surface.
A giant storm
The Great Red Spot is a giant anticyclonic storm on Jupiter, wider than Earth at roughly 14,000-16,000 km across, and has been tracked continuously since the 1830s.
Q 14Who discovered the four largest moons of the biggest planet in 1610?
Galileo Galilei
Galileo Galilei discovered the four largest moons of Jupiter (Io, Europa, Ganymede, and Callisto) in 1610. They are known as the Galilean moons in his honor and were the first moons discovered beyond Earth.
Q 15What is the tallest volcano in the solar system?
Olympus Mons
Olympus Mons on Mars stands about 21.9 km (72,000 ft) high, roughly 2.5 times the height of Mount Everest. It is a massive shield volcano about 600 km wide.
Q 16What are the rings of the second-largest planet made almost entirely of?
Water ice
The ring particles range from micrometres to metres in size and are almost pure water ice with only a trace of rocky material.
Q 17What region of the solar system lies beyond Neptune's orbit and contains Pluto?
Kuiper Belt
The Kuiper Belt is a doughnut-shaped region of icy objects that extends from Neptune's orbit (about 30 AU) to roughly 50 AU from the Sun. It is home to Pluto and several other dwarf planets.
Q 18What does one astronomical unit (AU) represent?
The distance from the Sun to Earth
Since 2012 it has been fixed at exactly 149,597,870,700 metres — about 150 million km, or roughly 499 light-seconds.
Q 19Which NASA mission flew past Pluto in 2015, providing the first close-up images?
New Horizons
NASA's New Horizons spacecraft flew past Pluto on July 14, 2015, revealing surprisingly youthful mountains, a heart-shaped nitrogen ice plain, and an unexpectedly complex surface.
Q 20What is the largest moon in our solar system?
Ganymede
Ganymede, a moon of Jupiter, is the largest moon in the solar system at 5,268 km across, bigger than the planet Mercury though only about half as massive.
Q 24What did Neil Armstrong and Buzz Aldrin name their landing site on the Moon?
Tranquility Base
Armstrong and Aldrin named their landing site Tranquility Base, located in the Sea of Tranquility (Mare Tranquillitatis) on the Moon's surface.
Q 25Which planet is tilted almost on its side, with an axial tilt of about 98 degrees?
Uranus
Uranus spins on an axis tilted about 98 degrees to its orbit, so it rolls around the Sun almost on its side, and each pole gets about 42 years of sunlight followed by 42 of darkness.
Q 26Which moon of Saturn has liquid methane lakes on its surface?
Titan
Titan is the only body in the solar system besides Earth known to have stable liquid on its surface. Its lakes and seas are filled with liquid methane and ethane, confirmed by the Cassini mission in 2007.
Q 27Which dwarf planet is the only confirmed one inside the main asteroid belt?
Ceres
Ceres was announced as a new planet when Giuseppe Piazzi spotted it on 1 January 1801, then demoted to an asteroid before being promoted again to dwarf planet in 2006.
Q 28Which moon in our solar system is the most volcanically active body?
Io
Io has more than 400 active volcanoes, driven by tidal heating as it is squeezed between its giant parent planet and the neighbouring large moons.
Q 29In what year were the twin Voyager probes launched?
1977
Both probes launched in 1977 to exploit a rare planetary alignment that occurs once every 175 years, giving humanity its first close-up views of the outer planets.
Q 30Which planet has the fastest winds in the solar system?
Neptune
Neptune has the fastest winds of any planet in the solar system, reaching speeds of up to 2,100 km/h (1,300 mph). This is surprising given Neptune's great distance from the Sun.