Planet Earth Trivia
0Loading crowd target
0Loading crowd target
7correct to beat the crowd
98 free Planet Earth trivia questions with answers — science & nature quiz, new questions added Oct 2026.
This planet Earth trivia quiz covers the planet as an astronomical object and as a home: its formation 4.5 billion years ago, the Theia impact that made the Moon, the iron core and the magnetic field it generates, the crust that is only 6 km thick under the oceans, the seven major tectonic plates, the 70.8% ocean cover, the nitrogen-oxygen atmosphere and its greenhouse effect, the 23.4-degree tilt behind the seasons, and the extremes from the Dead Sea to Everest and the Mariana Trench. The easy questions are the ones every classroom covers: which planet from the Sun, what the atmosphere is mostly made of, how long a year is. The harder ones ask which element makes up most of Earth's mass, how fast the Moon is receding, how many days a year had 620 million years ago, which mountain summit is farthest from Earth's centre, and when the magnetic field last flipped. It suits Earth Day quizzes and science classes alike; our earth science quiz and solar system quiz are the neighbouring pages. Every answer was checked against the encyclopaedia entry for the planet before publishing, and the sentence that supports it is stored with each question.
30 of 98 questions with answers and explanations. Play the quiz
Q 01Earth is which planet from the Sun?
Third
Third from the Sun puts Earth at a distance where surface water neither boils away nor freezes, making it the only planet in the Solar System with oceans on its surface.
Q 02Which ocean alone is larger than all of Earth's land combined?
Pacific
Pacific Ocean was named by Ferdinand Magellan, who sailed into it in 1520 and called it the 'peaceful sea' for the calm water he met after a perilous passage around South America.
Q 03About how many years ago did Earth form?
4.5 billion
4.5 billion years is a figure read from meteorites: plate tectonics has recycled Earth's own oldest rocks, so the age came from dating a meteorite in the 1950s.
Q 04Which Greek scholar first measured Earth's circumference, using shadows in Egypt?
Eratosthenes
Eratosthenes knew the midsummer Sun shone straight down a well at Syene, measured the shadow it cast in Alexandria at the same moment, and scaled up the distance between the two towns.
Q 05Which device gave the public the first simple, direct proof that Earth rotates?
Foucault's pendulum
Foucault's pendulum first swung for scientists invited to the Paris Observatory to 'come and see the Earth turn' in 1851, then for the public beneath the dome of the Panthéon.
Q 06What did Apollo crews leave on the Moon to measure its distance?
Laser reflectors
Laser reflectors set out by three Apollo crews bounce back pulses fired from observatories on Earth, and decades of timing the round trip have shown that the Moon is slowly drifting away.
Q 07Which Mars-sized object is thought to have struck Earth and formed the Moon?
Theia
Theia may not be entirely gone: a 2023 study proposed that two continent-sized blobs of dense rock deep in Earth's mantle are leftover pieces of it.
Q 08Which supercontinent held nearly all of Earth's land before splitting into today's continents?
Pangaea
Pangaea's break-up opened the Atlantic Ocean, which is why the coastlines facing each other across it still look like the two edges of one torn sheet.
Q 09Which geological epoch, the one we live in now, began as the last ice age ended?
Holocene
Holocene warmth frames the whole human story: all of recorded history, and the rise and fall of every civilization, has happened since the ice last retreated.
Q 10The asteroid that wiped out the non-avian dinosaurs struck what is now which country?
Mexico
Mexico's Yucatán Peninsula hides the buried Chicxulub crater; the impact flung up so much soot that sunlight dimmed worldwide, plants died back and food chains collapsed.
Q 11Which element makes up the largest share of Earth's mass?
Iron
Iron is Earth's most plentiful element by mass, yet little of it is underfoot: while the young planet was molten, most of it sank to the centre to form the core.
Q 12What is the name of the boundary between Earth's crust and mantle?
Mohorovičić discontinuity
Mohorovičić discontinuity was found in 1909, when Andrija Mohorovičić saw two sets of waves on his earthquake records and realised one had sped up through denser rock beneath the crust.
Q 13Which rock, erupted as lava along mid-ocean ridges, makes up most of the crust beneath Earth's oceans?
Basalt
Basalt is faintly magnetic, and stripes of alternating magnetism frozen into it on either side of the ridges gave the first solid proof that the sea floor spreads.
Q 21Which term describes Earth's slightly squashed shape, wider across the equator than from pole to pole?
Oblate spheroid
Oblate spheroid is the shape any fast-spinning ball of rock settles into: Earth's rotation flings its waistline outward, by about 43 km compared with the distance through the poles.
Q 22Which volcano's summit is the point on Earth's surface farthest from its centre?
Chimborazo
Chimborazo, in Ecuador, stands almost on the equator, where Earth bulges most, so its summit is about 2 km farther from the planet's centre than Everest's, though Everest rises far higher above sea level.
Q 23Challenger Deep, the deepest known point in Earth's oceans, lies in which trench?
Mariana Trench
Q 14Earth's outer core is in what state?
Liquid
Liquid metal cannot carry the sideways shear waves from earthquakes, so those waves vanish at the outer core, which is how seismologists worked out its state without ever seeing it.
Q 15Earth's inner core is as hot as the Sun's surface, so what keeps it solid?
Immense pressure
Immense pressure, from the weight of the whole planet above, squeezes the inner core's atoms so tightly that the metal cannot melt, however hot it gets.
Q 16Which radioactive isotope's slow decay is one of the main sources of Earth's internal heat?
Uranium-238
Uranium-238 and its fellow radioactive elements supply about half of the heat flowing out of Earth, a share physicists measured by catching the ghostly antineutrinos their decay gives off.
Q 17India's collision with Asia raised the Himalayas and which vast plateau behind them?
Tibetan Plateau
Tibetan Plateau rose with the Himalayas when India, once an island far to the south, drifted north and rammed into Asia; the collision has never stopped, so the mountains are still rising.
Q 18At which type of plate boundary do two plates slide past each other laterally?
Transform
Transform boundaries neither make nor destroy crust; California's San Andreas Fault is one, where land west of the fault grinds north-west past the rest of the state, storing up the strain its earthquakes release.
Q 19Which island nation straddles a mid-ocean ridge, slowly splitting as two tectonic plates pull apart?
Iceland
Iceland sits on the Mid-Atlantic Ridge, where the North American and Eurasian plates are pulling apart, so its ground keeps cracking open and filling with fresh lava.
Q 20What is the lowest point on Earth's land surface?
The Dead Sea
The Dead Sea's shore lies more than 400 m below sea level and keeps sinking, by about a metre a year, because river water that once fed the lake has been diverted.
Mariana Trench was first sounded in 1875 by the crew of HMS Challenger, which gave the deep its name; nobody reached the bottom until the bathyscaphe Trieste went down in 1960.
Q 24In recent decades, Earth's north magnetic pole has been drifting from Arctic Canada toward which region?
Siberia
Siberia is the pole's heading, and the drift became so quick that the world's navigation model, normally updated every five years, had to be revised ahead of schedule in 2019.
Q 25Which process in Earth's core generates the main part of its magnetic field?
Dynamo effect
Dynamo effect means the core works like a self-sustaining electric generator; the magnetic field it keeps going deflects the solar wind, which would otherwise strip away the ozone layer.
Q 26Which radiation belts trap high-energy particles inside Earth's magnetosphere?
Van Allen
Van Allen belts were the first big find of the space age: a radiation detector that physicist James Van Allen designed for Explorer 1, America's first satellite, revealed them in 1958.
Q 27What is the approximate acceleration due to gravity at Earth's surface?
9.8 m/s²
9.8 m/s² is Earth's pull at the surface; the Moon's is about a sixth as strong, which is why Apollo astronauts could take such famous bounding leaps across it.
Q 28What is the name for the phenomenon that keeps one face of the Moon always turned toward Earth?
Tidal locking
Tidal locking means the Moon spins exactly once per orbit, so we only ever see one side; it is no fluke, since every large moon in the Solar System has been braked by its planet in the same way.
Q 29The Sun is about 400 times the Moon's width but 400 times farther, allowing which event?
Total solar eclipse
A total solar eclipse depends on the two discs looking almost exactly the same size from Earth, a match that will not last: the Moon is drifting away and will one day be too small to cover the Sun.
Q 30The Moon drifts about 3.8 cm farther from Earth each year, roughly the pace at which what grows?
Fingernails
Fingernails grow about 3.5 mm a month, close to the Moon's retreat; the push comes from Earth's tides, whose drag also stretches our day by roughly two milliseconds each century.