Solar System Planets and Moons Quiz

Take on the Solar System Planets and Moons Quiz. Travel through questions about Pluto, Titan, Ganymede, Io, Europa, Enceladus, Saturn's hexagon

70 questions in 5 rounds · Published 18 October 2026

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Questions and answers

Round 1: Speed round

Question 1
How many known moons does Pluto have?
1. 3
2. 4
3. 5
4. 6
Show the answer
Answer: 5
Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra.
Source
- en.wikipedia.org/w/index.php
Question 2
Who discovered Titan?
1. Clyde Tombaugh
2. Galileo Galilei
3. William Herschel
4. Christiaan Huygens
Show the answer
Answer: Christiaan Huygens
Titan was discovered in 1655 by the Dutch astronomer Christiaan Huygens.
Source
- en.wikipedia.org/w/index.php
Question 3
In which year was Pluto discovered?
1. 1910
2. 1920
3. 1930
4. 1940
Show the answer
Answer: 1930
Pluto was discovered in 1930 by Clyde W. Tombaugh.
Source
- en.wikipedia.org/w/index.php
Question 4
Which moon is the largest moon of Saturn?
1. Ganymede
2. Titan
3. Europa
4. Triton
Show the answer
Answer: Titan
Titan is Saturn's largest moon and the Solar System's second-largest moon.
Source
- en.wikipedia.org/w/index.php
Question 5
Who first visited Pluto by spacecraft?
1. Cassini
2. Galileo
3. Voyager 2
4. New Horizons
Show the answer
Answer: New Horizons
New Horizons was the first spacecraft to visit Pluto and its moons.
Source
- en.wikipedia.org/w/index.php
Question 6
How many kilometres across is Titan?
1. 2,706.8
2. 3,100.0
3. 5,149.53
4. 5,270.0
Show the answer
Answer: 5,149.53
Titan's diameter is 5,149.53 kilometres.
Source
- en.wikipedia.org/w/index.php
Question 7
Which moon is the Solar System's largest?
1. Titan
2. Triton
3. Ganymede
4. Europa
Show the answer
Answer: Ganymede
Ganymede is the largest and most massive moon in the Solar System.
Source
- en.wikipedia.org/w/index.php
Question 8
Which moon has stable surface liquid besides Earth?
1. Titan
2. Triton
3. Ganymede
4. Europa
Show the answer
Answer: Titan
Titan is the only known object in the Solar System besides Earth with clear evidence of stable bodies of surface liquid.
Source
- en.wikipedia.org/w/index.php
Question 9
Who discovered Io in 1610?
1. Galileo Galilei
2. William Herschel
3. William Lassell
4. Clyde Tombaugh
Show the answer
Answer: Galileo Galilei
Io was discovered with the other Galilean moons in 1610 by Galileo Galilei.
Source
- en.wikipedia.org/w/index.php
Question 10
Which moon has one face permanently toward Saturn?
1. Titan
2. Europa
3. Ganymede
4. Triton
Show the answer
Answer: Titan
Titan is tidally locked to Saturn and permanently shows one face to Saturn.
Source
- en.wikipedia.org/w/index.php
Question 11
Which moon has a magnetic field of its own?
1. Ganymede
2. Titan
3. Triton
4. Europa
Show the answer
Answer: Ganymede
Ganymede is the only natural satellite in the Solar System with an internally generated magnetic field.
Source
- en.wikipedia.org/w/index.php
Question 12
In which year was Titan discovered?
1. 1610
2. 1655
3. 1789
4. 1846
Show the answer
Answer: 1655
Titan was discovered in 1655 by the Dutch astronomer Christiaan Huygens.
Source
- en.wikipedia.org/w/index.php
Question 13
How many active volcanoes does Io have?
1. 200
2. 300
3. 400
4. 500
Show the answer
Answer: 400
Io has over 400 active volcanoes.
Source
- en.wikipedia.org/w/index.php
Question 14
Which moon is the smallest Galilean moon?
1. Europa
2. Triton
3. Titan
4. Callisto
Show the answer
Answer: Europa
Europa is the smallest and least massive of Jupiter's four Galilean moons.
Source
- en.wikipedia.org/w/index.php
Question 15
Which moon has giant water-rich plumes?
1. Europa
2. Titan
3. Triton
4. Enceladus
Show the answer
Answer: Enceladus
Cassini discovered water-rich plumes venting from Enceladus's south polar region.
Source
- en.wikipedia.org/w/index.php
Question 16
Where is the Solar System's largest sea?
1. Titan
2. Triton
3. Ganymede
4. Europa
Show the answer
Answer: Titan
Kraken Mare, the largest sea on Titan, is on Titan.
Source
- en.wikipedia.org/w/index.php
Question 17
How many kilometres high can Io's volcanic plumes rise?
1. 100 km
2. 200 km
3. 500 km
4. 700 km
Show the answer
Answer: 500 km
Several of Io's volcanoes produce plumes as high as 500 km above the surface.
Source
- en.wikipedia.org/w/index.php
Question 18
Which takes the longest to orbit its planet?
1. Europa (moon)
2. Ganymede (moon)
3. Io (moon)
4. Titan (moon)
Show the answer
Answer: Titan (moon)
Titan orbits Saturn every 15 days and 22 hours, longer than Ganymede, Europa, Io, or Enceladus take to orbit their planets.
Sources
Question 19
Where is Saturn's hexagon located?
1. Saturn's north pole
2. Saturn's south pole
3. Jupiter's north pole
4. Neptune's south pole
Show the answer
Answer: Saturn's north pole
Saturn's hexagon is located at about 78°N.
Source
- en.wikipedia.org/w/index.php
Question 20
Who sent Voyager 1 past Io?
1. Voyager 2
2. Galileo
3. Cassini
4. Voyager 1
Show the answer
Answer: Voyager 1
Voyager 1 flew past Io on 5 March 1979.
Source
- en.wikipedia.org/w/index.php

Round 2: Fact round

Question 21
Which statement about Europa is true?
1. Europa is tidally locked to Neptune.
2. Europa is tidally locked to Saturn.
3. Europa is tidally locked to the Sun.
4. Europa is tidally locked to Jupiter.
Show the answer
Answer: Europa is tidally locked to Jupiter.
Europa is tidally locked to Jupiter, so one hemisphere constantly faces the planet.
Source
- en.wikipedia.org/w/index.php
Question 22
Which does not belong with Jupiter's Galilean moons?
1. Europa
2. Ganymede
3. Io
4. Titan
Show the answer
Answer: Titan
Titan is Saturn's largest moon, while Io, Europa, and Ganymede are Galilean moons of Jupiter.
Sources
Question 23
Which of these is NOT a natural satellite?
1. Europa
2. Ganymede
3. Io
4. Pluto
Show the answer
Answer: Pluto
Pluto is a dwarf planet in the Kuiper belt, unlike the listed moons.
Sources
Question 24
Which moon is NOT associated with Jupiter?
1. the moon Titan
2. the moon Ganymede
3. the moon Europa
4. the moon Io
Show the answer
Answer: the moon Titan
Ganymede, Europa, and Io share a 1:2:4 orbital rhythm around Jupiter. Titan instead orbits Saturn.
Sources
- en.wikipedia.org/w/index.php
- en.wikipedia.org/w/index.php
Question 25
In which year did Voyager 2 fly by Triton?
1. 1979
2. 1981
3. 1989
4. 1997
Show the answer
Answer: 1989
Voyager 2 encountered Triton in 1989.
Source
- en.wikipedia.org/w/index.php
Question 26
Which is NOT one of Pluto's five known moons?
1. Hydra
2. Europa
3. Charon
4. Styx
Show the answer
Answer: Europa
Pluto's five known moons are Charon, Styx, Nix, Kerberos, and Hydra. Europa is not among them.
Source
- en.wikipedia.org/w/index.php
Question 27
Which moon is Saturn's E ring mainly made from?
1. Europa
2. Triton
3. Ganymede
4. Enceladus
Show the answer
Answer: Enceladus
Enceladus is the main source of material composing Saturn's E ring.
Source
- en.wikipedia.org/w/index.php
Question 28
Which statement about Io is true?
1. Io is the coldest object recorded.
2. Io is the least geologically active object.
3. Io is the most geologically active object.
4. Io is the smoothest solid object.
Show the answer
Answer: Io is the most geologically active object.
Io is described as the most geologically active object in the Solar System.
Source
- en.wikipedia.org/w/index.php
Question 29
Who made six close flybys of Ganymede?
1. Voyager 2
2. Galileo
3. Cassini
4. Juno
Show the answer
Answer: Galileo
The Galileo craft made six close flybys of Ganymede from 1995 to 2000.
Source
- en.wikipedia.org/w/index.php
Question 30
Where does Triton always keep one face pointed?
1. Uranus
2. Saturn
3. Neptune
4. Jupiter
Show the answer
Answer: Neptune
Triton's tidally locked rotation keeps one face oriented toward Neptune.
Source
- en.wikipedia.org/w/index.php

Round 3: Speed round

Question 31
How many days does Europa take to orbit Jupiter?
1. 1.77 days
2. 3.55 days
3. 7.16 days
4. 15.92 days
Show the answer
Answer: 3.55 days
Europa orbits Jupiter in roughly 3.55 days.
Source
- en.wikipedia.org/w/index.php
Question 32
In which year did the Galileo spacecraft arrive at Jupiter?
1. 1989
2. 1995
3. 2007
4. 2016
Show the answer
Answer: 1995
The Galileo spacecraft arrived at Jupiter in 1995, following a six-year journey from Earth.
Source
- en.wikipedia.org/w/index.php
Question 33
In which year was Europa Clipper launched?
1. 2006
2. 2016
3. 2022
4. 2024
Show the answer
Answer: 2024
NASA's Europa Clipper was launched on 14 October 2024.
Source
- en.wikipedia.org/w/index.php
Question 34
Which moon has the coldest recorded temperature?
1. Triton
2. Ganymede
3. Titan
4. Europa
Show the answer
Answer: Triton
Triton has the coldest recorded temperature in the Solar System, 38 K.
Source
- en.wikipedia.org/w/index.php
Question 35
Which moon is Jupiter's innermost Galilean moon?
1. Io
2. Dione
3. Rhea
4. Titan
Show the answer
Answer: Io
Io is the innermost of Jupiter's four Galilean moons.
Source
- en.wikipedia.org/w/index.php
Question 36
Who shares Ganymede's discovery credit with Galileo Galilei?
1. Clyde Tombaugh
2. William Lassell
3. Galileo Galilei
4. Simon Marius
Show the answer
Answer: Simon Marius
Ganymede's discovery is credited to Simon Marius and Galileo Galilei.
Source
- en.wikipedia.org/w/index.php
Question 37
Who discovered Europa with Galileo?
1. Clyde Tombaugh
2. William Herschel
3. William Lassell
4. Simon Marius
Show the answer
Answer: Simon Marius
Simon Marius and Galileo Galilei independently discovered Europa.
Source
- en.wikipedia.org/w/index.php
Question 38
Who concluded Jupiter's apparent stars were bodies orbiting it?
1. William Herschel
2. Christiaan Huygens
3. Clyde Tombaugh
4. Galileo Galilei
Show the answer
Answer: Galileo Galilei
Galileo Galilei concluded that the apparent stars were actually bodies orbiting Jupiter.
Source
- en.wikipedia.org/w/index.php
Question 39
Which moon has the highest density of any natural satellite?
1. Io
2. Titan
3. Dione
4. Rhea
Show the answer
Answer: Io
Io has the highest density of any natural satellite.
Source
- en.wikipedia.org/w/index.php
Question 40
Which moon is known to have cryolava lakes?
1. Triton
2. Europa
3. Titan
4. Ganymede
Show the answer
Answer: Triton
Triton is the only icy body known to feature cryolava lakes.
Source
- en.wikipedia.org/w/index.php
Question 41
Which moon is the Solar System's smoothest solid object?
1. Europa
2. Titan
3. Triton
4. Callisto
Show the answer
Answer: Europa
Europa is the smoothest known solid object in the Solar System.
Source
- en.wikipedia.org/w/index.php
Question 42
Which moon orbits Neptune backward?
1. Ganymede
2. Triton
3. Titan
4. Europa
Show the answer
Answer: Triton
Triton is the only large moon in the Solar System with a retrograde orbit.
Source
- en.wikipedia.org/w/index.php
Question 43
How many hours does Enceladus take to orbit Saturn?
1. 32.9 hours
2. 42.5 hours
3. 78.0 hours
4. 96.0 hours
Show the answer
Answer: 32.9 hours
Enceladus orbits Saturn every 32.9 hours.
Source
- en.wikipedia.org/w/index.php
Question 44
In which year did Juno enter Jupiter orbit?
1. 1995
2. 2007
3. 2016
4. 2024
Show the answer
Answer: 2016
The Juno spacecraft entered orbit around Jupiter on 5 July 2016.
Source
- en.wikipedia.org/w/index.php
Question 45
Which moon orbits Jupiter in about seven days?
1. Ganymede
2. Titan
3. Callisto
4. Europa
Show the answer
Answer: Ganymede
Ganymede orbits Jupiter in roughly seven days.
Source
- en.wikipedia.org/w/index.php
Image: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill, CC BY 2.0, https://commons.wikimedia.org/wiki/File:Ganymede_-_Perijove_34_Composite.jpg
Question 46
How many Earth years is one Plutonian year?
1. 147.94
2. 247.94
3. 347.94
4. 447.94
Show the answer
Answer: 247.94
One Plutonian year corresponds to 247.94 Earth years.
Source
- en.wikipedia.org/w/index.php
Question 47
Which moon has an oxygen-rich thin atmosphere?
1. Europa
2. Triton
3. Callisto
4. Titan
Show the answer
Answer: Europa
Europa has a very thin atmosphere composed primarily of oxygen.
Source
- en.wikipedia.org/w/index.php
Image: Celestialobjects, CC BY 4.0, https://commons.wikimedia.org/wiki/File:Jupiter_and_Europa_NASA-JPL-PBudassi.jpg
Question 48
About how many kilometres high is Saturn's hexagon?
1. 200
2. 300
3. 400
4. 500
Show the answer
Answer: 300
Saturn's hexagon is around 300 kilometres high.
Source
- en.wikipedia.org/w/index.php
Question 49
In which year did New Horizons fly by Io?
1. 1979
2. 1997
3. 2007
4. 2016
Show the answer
Answer: 2007
New Horizons flew by Io on 28 February 2007.
Source
- en.wikipedia.org/w/index.php
Question 50
How much material do Enceladus's geysers eject each second?
1. 100 kilograms per second
2. 200 kilograms per second
3. 300 kilograms per second
4. 400 kilograms per second
Show the answer
Answer: 200 kilograms per second
Enceladus's geysers eject material into space at about 200 kilograms per second.
Source
- en.wikipedia.org/w/index.php

Round 4: Fact round

Question 51
Where did Cassini find water-rich plumes?
1. Ganymede
2. Triton
3. Europa
4. Enceladus
Show the answer
Answer: Enceladus
Cassini discovered water-rich plumes at Enceladus's south polar region.
Source
- en.wikipedia.org/w/index.php
Question 52
Which was not discovered in 1610?
1. Europa (moon)
2. Ganymede (moon)
3. Io (moon)
4. Titan (moon)
Show the answer
Answer: Titan (moon)
Io, Europa, and Ganymede were observed in 1610, while Titan was discovered in 1655.
Sources
Question 53
Which statement about Ganymede is true?
1. Ganymede has Saturn's magnetic field.
2. Ganymede has an internal magnetic field.
3. Ganymede has no magnetic field.
4. Ganymede has Earth's magnetic field.
Show the answer
Answer: Ganymede has an internal magnetic field.
Ganymede is the only natural satellite in the Solar System known to have an internally generated magnetic field.
Source
- en.wikipedia.org/w/index.php
Question 54
Which moon is Neptune's largest natural satellite?
1. Triton
2. Enceladus
3. Europa
4. Titan
Show the answer
Answer: Triton
Triton is the largest natural satellite of Neptune.
Source
- en.wikipedia.org/w/index.php
Question 55
Who discovered Enceladus?
1. William Lassell
2. Christiaan Huygens
3. Clyde Tombaugh
4. William Herschel
Show the answer
Answer: William Herschel
Enceladus was discovered on August 28, 1789, by William Herschel.
Source
- en.wikipedia.org/w/index.php
Question 56
In which year was Ganymede observed by Galileo and Marius?
1. 1600
2. 1610
3. 1620
4. 1630
Show the answer
Answer: 1610
Ganymede's discovery is credited to Galileo Galilei and Simon Marius, who both observed it in 1610.
Source
- en.wikipedia.org/w/index.php
Question 57
Who discovered Triton?
1. Christiaan Huygens
2. Clyde Tombaugh
3. William Lassell
4. William Herschel
Show the answer
Answer: William Lassell
English astronomer William Lassell discovered Triton on October 10, 1846.
Source
- en.wikipedia.org/w/index.php
Question 58
In which year was Enceladus discovered?
1. 1655
2. 1789
3. 1846
4. 1930
Show the answer
Answer: 1789
William Herschel discovered Enceladus on August 28, 1789.
Source
- en.wikipedia.org/w/index.php
Question 59
Which moon is fourth-largest in the Solar System?
1. Dione
2. Io
3. Titan
4. Rhea
Show the answer
Answer: Io
Io is the fourth-largest natural satellite in the Solar System.
Source
- en.wikipedia.org/w/index.php
Question 60
Which statement about Saturn's hexagon is true?
1. Each side is about 3,000 km long.
2. Each side is about 9,000 km long.
3. Each side is about 14,500 km long.
4. Each side is about 30,000 km long.
Show the answer
Answer: Each side is about 14,500 km long.
The sides of Saturn's hexagon are about 14,500 kilometres long.
Source
- en.wikipedia.org/w/index.php

Round 5: Final round

Question 61
Where is Saturn's decagon-shaped atmospheric wave?
1. Enceladus's south pole
2. Saturn's north pole
3. Triton's north pole
4. Saturn's south pole
Show the answer
Answer: Saturn's south pole
Saturn's south pole has a decagon-shaped atmospheric wave pattern.
Source
- en.wikipedia.org/w/index.php
Question 62
Which statement about Triton is true?
1. Triton's orbit precesses every 578 Earth years.
2. Triton's orbit precesses every 678 Earth years.
3. Triton's orbit precesses every 778 Earth years.
4. Triton's orbit precesses every 878 Earth years.
Show the answer
Answer: Triton's orbit precesses every 678 Earth years.
Triton's orbit precesses with a period of about 678 Earth years.
Source
- en.wikipedia.org/w/index.php
Question 63
How many kilometres long are Saturn's hexagon sides?
1. 12,500 km
2. 13,500 km
3. 14,500 km
4. 15,500 km
Show the answer
Answer: 14,500 km
The sides of Saturn's hexagon are about 14,500 kilometres long.
Source
- en.wikipedia.org/w/index.php
Question 64
Which moon is the only large moon with a retrograde orbit?
1. Europa
2. Triton
3. Ganymede
4. Titan
Show the answer
Answer: Triton
Triton is the only large moon in the Solar System with a retrograde orbit.
Source
- en.wikipedia.org/w/index.php
Question 65
In which year did Cassini revisit Saturn's hexagon?
1. 1981
2. 1995
3. 2006
4. 2016
Show the answer
Answer: 2006
Cassini-Huygens revisited Saturn's hexagon in 2006.
Source
- en.wikipedia.org/w/index.php
Question 66
How many kilometres long can Enceladus's canyons be?
1. 100 km
2. 200 km
3. 500 km
4. 700 km
Show the answer
Answer: 200 km
Enceladus's tectonic canyons can be up to 200 km long.
Source
- en.wikipedia.org/w/index.php
Question 67
Which moon did Juno fly within about 320 km of in 2022?
1. Enceladus
2. Titan
3. Europa
4. Ganymede
Show the answer
Answer: Europa
Juno flew within around 320 kilometres of Europa in September 2022.
Source
- en.wikipedia.org/w/index.php
Question 68
In which year was Triton discovered?
1. 1789
2. 1816
3. 1846
4. 1876
Show the answer
Answer: 1846
English astronomer William Lassell discovered Triton on October 10, 1846.
Source
- en.wikipedia.org/w/index.php
Question 69
Where does Saturn lack a hexagon-shaped pattern?
1. Saturn's E ring
2. Saturn's south pole
3. Saturn's equator
4. Saturn's north pole
Show the answer
Answer: Saturn's south pole
Hubble observations verified that Saturn's south pole does not have a hexagon.
Source
- en.wikipedia.org/w/index.php
Question 70
Where is Enceladus's geyser snow deepest?
1. Triton
2. Enceladus
3. Ganymede
4. Europa
Show the answer
Answer: Enceladus
Enceladus's geyser-deposited snow reaches an estimated 700 meters at its thickest.
Source
- en.wikipedia.org/w/index.php

Image credits

NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill, CC BY 2.0, https://commons.wikimedia.org/wiki/File:Ganymede_-_Perijove_34_Composite.jpg
Celestialobjects, CC BY 4.0, https://commons.wikimedia.org/wiki/File:Jupiter_and_Europa_NASA-JPL-PBudassi.jpg

Sound credits

Music: AI-generated instrumentals (ACE-Step, Apache-2.0)
Voice: synthetic (Qwen3-TTS-12Hz-1.7B-CustomVoice, Apache-2.0)