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50 free Planet Earth trivia questions with answers — science & nature quiz, new questions added Aug 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 50 questions with answers and explanations. Play the quiz
Q 01Earth is which planet from the Sun?
Third
It is the only astronomical object known to harbor life and the only Solar System world with liquid surface water.
Q 02What percentage of Earth's crust is covered by ocean?
70.8%
The remaining 29.2% is land, mostly in the land hemisphere.
Q 03About how many years ago did Earth form?
4.5 billion
It formed from gas and dust in the early Solar System, taking perhaps 70 to 100 million years.
Q 04Roughly what is Earth's circumference?
40,000 km
It is rounded into an ellipsoid and is the densest planet in the Solar System.
Q 05How long does Earth take to rotate once on its axis?
About 23 hours 56 minutes
The solar day of 24 hours is slightly longer than this sidereal rotation.
Q 06At what distance does the Moon orbit Earth?
384,400 km
That is 1.28 light-seconds; the Moon is roughly a quarter as wide as Earth.
Q 07Which Mars-sized object is thought to have struck Earth and formed the Moon?
Theia
It had about 10% of Earth's mass; two remnants of it may still sit inside Earth.
Q 08Which supercontinent began to break apart about 180 million years ago?
Pangaea
Rodinia broke up around 750 Ma and Pannotia formed at 600–540 Ma before it.
Q 09The last ice age, the Last Glacial Period, ended about how many years ago?
11,700
Glacial cycles have repeated roughly every 21,000, 41,000 and 100,000 years.
Q 10The asteroid impact that ended the non-avian dinosaurs happened how many million years ago?
66
It largely spared small animals such as insects, mammals, lizards and birds.
Q 11Which element makes up the largest share of Earth's mass, at 32.1%?
Iron
Oxygen is next at 30.1%; the core itself is 88.8% iron.
Q 12What is the name of the boundary between Earth's crust and mantle?
Mohorovičić discontinuity
The crust above it is about 6 km thick under the oceans and 30–50 km under continents.
Q 13How thick is Earth's crust beneath the oceans?
About 6 km
Under the continents it thickens to 30–50 km.
Q 14Earth's outer core is in what state?
Q 21What is the lowest point on Earth's land surface?
The Dead Sea
It sits at −418 m; the highest point, Everest, is 8,848 m.
Q 22How much longer is Earth's diameter at the equator than at the poles?
43 km
The rotation bulge is why Chimborazo's summit, not Everest's, is farthest from Earth's centre.
Q 23Which volcano's summit is the point on Earth's surface farthest from its centre?
Chimborazo
It is in Ecuador, near the equatorial bulge.
Q 24How deep is the Mariana Trench below local sea level?
Liquid
It lies above a solid inner core whose radius is about one-fifth of Earth's.
Q 15The temperature at Earth's centre may reach up to roughly what?
6,000 °C
Pressure there could reach 360 gigapascals, and the heat comes partly from radioactive decay.
Q 16Which isotope is NOT one of the three major heat-producing isotopes inside Earth?
Carbon-14
Carbon-14 is used for dating, not planetary heating.
Q 17How many major tectonic plates does Earth have?
Seven
Pacific, North American, Eurasian, African, Antarctic, Indo-Australian and South American.
Q 18Which is the fastest-moving tectonic plate, at about 75 mm per year?
Cocos
The slowest is the South American Plate at about 10.6 mm a year.
Q 19At which type of plate boundary do two plates slide past each other laterally?
Transform
Convergent boundaries bring plates together and divergent ones pull them apart.
Q 20The oldest oceanic crust, in the western part of the largest ocean, is about how old?
200 Ma
Most ocean floor is under 100 Ma old because it is recycled by subduction (Ma = million years, Ga = billion years).
10,925 m
It shortens Earth's average radius by 0.17%.
Q 25Approximately when did Earth's magnetic field last reverse?
700,000 years ago
Reversals come at irregular intervals averaging a few times every million years.
Q 26Which process in Earth's core generates the main part of its magnetic field?
Dynamo effect
It converts the energy of convection in the liquid outer core into magnetic field energy.
Q 27Which radiation belts trap high-energy particles inside Earth's magnetosphere?
Van Allen
Particles diverted along field lines into the ionosphere cause auroras.
Q 28What is the approximate acceleration due to gravity near Earth's surface?
9.8 m/s²
Local differences in topography and geology produce small gravity anomalies.
Q 29How often do the Earth and Moon orbit their common barycentre, relative to the stars?
27.32 days
The synodic month, new moon to new moon, is longer at 29.53 days.
Q 30The Sun's diameter is about how many times the Moon's, explaining their matching size in the sky?
400
It is also about 400 times more distant, which is why total solar eclipses are possible.