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The big facts page

103 Jupiter facts, all checked

Every fact on this site in one place, each linked to its NASA, JPL or ESA source. Our build checks each one against the source text; see the sources page. Things that can change carry the date we checked them.

Jump to: The basics | Size and distance | Days and years | Gravity, air and temperature | Inside Jupiter | Storms, stripes and rings | The moons | Io | Europa | Ganymede | Callisto | Missions

The basics

  1. 1 Jupiter is the fifth planet from the Sun, and the largest in the solar system by far. NASA Science: Jupiter
  2. 2 Jupiter is more than twice as massive as all the other planets put together. NASA Science: Jupiter
  3. 3 Jupiter is the largest and oldest planet in our solar system. NASA Science: Jupiter
  4. 4 Jupiter is named after the king of the gods in Roman mythology. NASA Science: Jupiter facts
  5. 5 Most of Jupiter’s moons are named after characters from mythology linked to Jupiter or his Greek counterpart, Zeus. NASA Science: Jupiter facts
  6. 6 Jupiter has the same ingredients as a star, but it never grew massive enough to ignite. NASA Science: Jupiter facts
  7. 7 Like the Sun, Jupiter is made mostly of hydrogen and helium. NASA Science: Jupiter facts
  8. 8 Jupiter formed with the rest of the solar system about 4.6 billion years ago. NASA Science: Jupiter facts
  9. 9 Jupiter has been known since ancient times: you can see it with just your eyes. NASA Space Place: All about Jupiter
  10. 10 The first detailed observations of Jupiter were made by Galileo Galilei in 1610, with a small, homemade telescope. NASA Science: Jupiter
  11. 11 Jupiter itself is probably too extreme for life as we know it, but some of its moons may not be. NASA Science: Jupiter facts

Size and distance

  1. 12 Jupiter’s mean radius is 69,911 km, so it is 11 times wider than Earth. NASA Science: Jupiter facts
  2. 13 If Earth were the size of a grape, Jupiter would be about as big as a basketball. NASA Science: Jupiter facts
  3. 14 If Jupiter were a hollow shell, 1,000 Earths could fit inside. NASA Science: Jupiter
  4. 15 Jupiter has 317.83 times the mass of Earth. NASA NSSDC: Jupiter fact sheet
  5. 16 Jupiter’s equatorial radius is 71,492 km and its polar radius is 66,854 km: it is squashed, wider round the middle. NASA NSSDC: Jupiter fact sheet
  6. 17 In 2026, NASA reported that Juno’s data show Jupiter is about 8 km narrower at the equator and 24 km flatter at the poles than previously thought. NASA Science: Juno redefines the size and shape of Jupiter (2026)
  7. 18 Jupiter orbits an average of 778 million km from the Sun: 5.2 astronomical units. NASA Science: Jupiter facts
  8. 19 Sunlight takes 43 minutes to travel from the Sun to Jupiter. NASA Science: Jupiter facts
  9. 20 Jupiter comes as close as 588.5 million km to Earth, and gets as far as 968.5 million km away. NASA NSSDC: Jupiter fact sheet
  10. 21 Earth’s equatorial radius is 6,378.1 km. Double it and Earth is 12,756 km wide (our sum). NASA NSSDC: Jupiter fact sheet
  11. 22 Jupiter’s average density is 1,326 kg per cubic metre, about a quarter of Earth’s (5,513). NASA NSSDC: Jupiter fact sheet

Days and years

  1. 23 Jupiter has the shortest day in the solar system: it spins once in about 9.9 hours. NASA Science: Jupiter facts
  2. 24 A day on Jupiter (sunrise to sunrise) lasts 9.9259 hours. Earth’s lasts 24 hours. NASA NSSDC: Jupiter fact sheet
  3. 25 Jupiter takes 4,332.589 Earth days to orbit the Sun once: about 12 Earth years. NASA NSSDC: Jupiter fact sheet
  4. 26 A year on Jupiter is about 12 Earth years (4,333 Earth days). NASA Science: Jupiter facts
  5. 27 Jupiter is tilted by just 3 degrees, so it spins nearly upright and doesn’t have big seasons. NASA Science: Jupiter facts

Gravity, air and temperature

  1. 28 Gravity at Jupiter’s 1-bar cloud level averages 25.92 m/s², 2.640 times Earth’s 9.82 m/s². NASA NSSDC: Jupiter fact sheet
  2. 29 To escape Jupiter’s gravity you’d need 59.5 km per second. From Earth it’s 11.19. NASA NSSDC: Jupiter fact sheet
  3. 30 Jupiter has no true surface. It is mostly swirling gases and liquids, so a spacecraft would have nowhere to land. NASA Science: Jupiter facts
  4. 31 The pressures and temperatures deep inside Jupiter would crush, melt and vaporise a spacecraft trying to fly in. NASA Science: Jupiter facts
  5. 32 At the level where the pressure equals Earth’s sea level (1 bar), Jupiter’s air is about −108 °C. NASA NSSDC: Jupiter fact sheet
  6. 33 Jupiter’s atmosphere is about 89.8% hydrogen and 10.2% helium. NASA NSSDC: Jupiter fact sheet

Inside Jupiter

  1. 34 Deep down, pressure squeezes hydrogen gas into a liquid, giving Jupiter the largest ocean in the solar system: an ocean of hydrogen, not water. NASA Science: Jupiter facts
  2. 35 Deeper still, the liquid hydrogen may become electrically conducting, like a metal. NASA Science: Jupiter facts
  3. 36 Juno’s measurements suggest Jupiter’s core is larger than expected and not solid: scientists call it dilute, or “fuzzy”. NASA Science: Jupiter facts
  4. 37 Jupiter’s magnetic field is 16 to 54 times as powerful as Earth’s. NASA Science: Jupiter facts
  5. 38 Jupiter’s magnetosphere stretches into a tadpole-shaped tail more than 1 billion km long, as far as Saturn’s orbit. NASA Science: Jupiter facts
  6. 39 Jupiter has auroras too, hundreds of times more energetic than Earth’s. NASA Space Place: All about Jupiter

Storms, stripes and rings

  1. 40 The dark orange stripes are called belts and the lighter bands are zones. Their winds blow east and west in opposite directions. NASA Science: Jupiter facts
  2. 41 Jupiter’s stripes and swirls are cold, windy clouds of ammonia and water, floating in hydrogen and helium. NASA Science: Jupiter facts
  3. 42 Jupiter probably has three cloud layers: ammonia ice on top, ammonium hydrosulfide in the middle, and water ice and vapour deepest down. NASA Science: Jupiter facts
  4. 43 Some of Jupiter’s winds reach 539 km/h at the equator. NASA Science: Jupiter facts
  5. 44 The Great Red Spot is a giant storm bigger than Earth. NASA Science: Jupiter facts
  6. 45 NASA’s Jupiter facts page says the Great Red Spot has been observed for more than 300 years. NASA Science: Jupiter facts · checked 27 Oct 2026
  7. 46 A 2024 NASA Hubble article says astronomers have observed it for at least 150 years. NASA Science: Hubble watches the Great Red Spot behave like a stress ball (2024) · checked 27 Oct 2026
  8. 47 Observations from the late 1800s measured the Great Red Spot as up to 25,500 miles (about 41,000 km) on its long axis. NASA Science: Jupiter’s Great Red Spot is shrinking (2014)
  9. 48 Voyager 1 and 2 measured it at 14,500 miles (about 23,300 km) across in 1979. NASA Science: Jupiter’s Great Red Spot is shrinking (2014)
  10. 49 A 1995 Hubble photo put its long axis at about 13,020 miles (about 20,950 km). NASA Science: Jupiter’s Great Red Spot is shrinking (2014)
  11. 50 In 2009 it measured 11,130 miles (about 17,910 km) across. NASA Science: Jupiter’s Great Red Spot is shrinking (2014)
  12. 51 In 2014, Hubble measured it at about 10,250 miles (about 16,500 km) across, the smallest ever measured at that time. NASA Science: Jupiter’s Great Red Spot is shrinking (2014)
  13. 52 Astronomers have watched the Great Red Spot shrink since the 1930s, and from 2012 it shrank faster, turning from an oval towards a circle. NASA Science: Jupiter’s Great Red Spot is shrinking (2014) · checked 27 Oct 2026
  14. 53 Hubble watched it for 90 days in 2023–24 and saw it jiggle in size and shape, like a bowl of jelly. The cause is unknown. NASA Science: Hubble watches the Great Red Spot behave like a stress ball (2024)
  15. 54 Juno’s gravity data suggest the Great Red Spot reaches about 500 km below the cloud tops. NASA Science: Jupiter facts
  16. 55 Three smaller ovals merged to form the Little Red Spot, about half the size of the Great Red Spot. NASA Science: Jupiter facts
  17. 56 Juno found giant cyclones at Jupiter’s poles: eight in an octagon in the north and five in a pentagon in the south. NASA Science: Jupiter facts
  18. 57 Jupiter’s jet streams reach about 3,200 km deep. NASA Science: Jupiter facts
  19. 58 Jupiter has rings, discovered by Voyager 1 in 1979. They are dark and faint, and hard to see unless the Sun is behind them. NASA Science: Jupiter facts

The moons

  1. 59 Jupiter has 115 moons officially recognised by the International Astronomical Union. NASA Science: Jupiter facts · checked 27 Oct 2026
  2. 60 Some NASA pages still give an older count of 95, including the NSSDC satellite fact sheet. NASA NSSDC: Jovian satellite fact sheet · checked 27 Oct 2026
  3. 61 Jupiter also has thousands of small objects in its orbit. NASA Science: Jupiter moons · checked 27 Oct 2026
  4. 62 The four largest moons, Io, Europa, Ganymede and Callisto, were first seen by Galileo Galilei in 1610. They are called the Galilean satellites. NASA Science: Jupiter moons
  5. 63 With four large moons and many small ones, Jupiter is like a miniature solar system. NASA Science: Jupiter moons
  6. 64 They were the first moons ever found going round a planet other than Earth. NASA Science: Io facts
  7. 65 Galileo called them the Medicean planets and numbered them I, II, III and IV. The names Io, Europa, Ganymede and Callisto were adopted in the mid-1800s. NASA Science: Io facts
  8. 66 Io, Europa and Ganymede are in step: each time Ganymede goes round Jupiter once, Europa goes round twice and Io four times. NASA Science: Ganymede facts
  9. 67 All four Galilean moons are tidally locked: the same side always faces Jupiter. NASA Science: Ganymede facts
  10. 68 Io goes round Jupiter in 1.769 days, Europa in 3.551, Ganymede in 7.155 and Callisto in 16.689. NASA NSSDC: Jovian satellite fact sheet
  11. 69 Their radii: Io 1,821.5 km, Europa 1,560.8 km, Ganymede 2,631.2 km, Callisto 2,410.3 km. NASA NSSDC: Jovian satellite fact sheet

Io

  1. 70 Io is the most volcanically active world in the solar system, with hundreds of volcanoes. Some throw lava fountains dozens of kilometres high. NASA Science: Io facts
  2. 71 Io’s volcanoes are powered by a tug-of-war between Jupiter’s gravity and precisely timed pulls from Europa and Ganymede. NASA Science: Io facts
  3. 72 Tides make Io’s solid surface bulge up and down by as much as 100 metres. NASA Science: Io facts
  4. 73 Jupiter’s magnetic field strips about 1 tonne of material off Io every second. NASA Science: Io facts
  5. 74 In mythology, Io was a woman turned into a cow during a quarrel between Zeus (Jupiter) and his wife, Juno. NASA Science: Io facts
  6. 75 NASA’s Juno mission is named after the goddess, who could see through clouds. The spacecraft peers through Jupiter’s clouds too. NASA Science: Io facts

Europa

  1. 76 Europa probably has a saltwater ocean under its icy shell, holding twice as much water as Earth’s global ocean. NASA Science: Europa
  2. 77 Europa may be one of the most promising places in our solar system to find environments suitable for life beyond Earth. NASA Science: Europa
  3. 78 Europa is the fourth largest of Jupiter’s moons and the sixth-closest to the planet. NASA Science: Europa

Ganymede

  1. 79 Ganymede is the largest moon in the solar system, bigger than the planet Mercury and the dwarf planet Pluto. NASA Science: Ganymede facts
  2. 80 Ganymede is the only moon known to have its own magnetic field, discovered by Galileo in 1996. It even has auroras. NASA Science: Ganymede facts
  3. 81 Ganymede may have an underground saltwater ocean with more water than all the water on Earth’s surface. NASA Science: Ganymede facts
  4. 82 In mythology, Ganymede was carried to Olympus by Zeus disguised as an eagle, and became cupbearer to the gods. NASA Science: Ganymede facts

Callisto

  1. 83 Callisto is the most heavily cratered object in our solar system. NASA Science: Ganymede facts
  2. 84 Galileo’s data suggest Callisto may hide a salty ocean, perhaps about 250 km below its surface, though it may not exist at all. NASA Science: Callisto facts
  3. 85 In Greek mythology, Callisto was a woman turned into a bear by Zeus. NASA Science: Callisto facts
  4. 86 Callisto is Jupiter’s second largest moon and the third largest moon in the solar system. NASA Science: Callisto facts

Missions

  1. 87 Pioneer 10, launched on 2 March 1972, was the first spacecraft to fly past Jupiter, making its closest approach on 4 December 1973. NASA Science: Pioneer 10
  2. 88 Its sibling, Pioneer 11, flew even closer to Jupiter in 1974 on its way to Saturn. NASA Science: Jupiter exploration
  3. 89 Voyager 1 flew past in March 1979 and found a thin ring, two new moons and active volcanoes on Io. NASA Science: Jupiter exploration
  4. 90 Voyager 1’s closest approach was on 5 March 1979, 280,000 km from Jupiter. NASA Science: Voyager 1
  5. 91 Galileo was the first spacecraft to orbit an outer planet. It arrived at Jupiter on 7 December 1995 and orbited 34 times. NASA Science: Galileo
  6. 92 Galileo dropped a probe into Jupiter’s atmosphere: the first entry probe into an outer planet. NASA Science: Galileo
  7. 93 Galileo was deliberately sent into Jupiter on 21 September 2003, to protect a possible ocean on Europa. NASA Science: Galileo
  8. 94 In July 1994, pieces of comet Shoemaker-Levy 9 smashed into Jupiter, from 16 to 22 July: the first time spacecraft watched two solar system bodies collide. NASA Science: Comet Shoemaker-Levy 9
  9. 95 When it was found in 1993, the comet was already torn into more than 20 pieces by Jupiter’s gravity. NASA Science: Comet Shoemaker-Levy 9
  10. 96 Cassini explored the Jupiter system for about six months, from October 2000 to March 2001, on its way to Saturn. NASA Science: Jupiter exploration
  11. 97 Juno launched on 5 August 2011 and entered orbit around Jupiter on 4 July 2016. NASA JPL: Juno
  12. 98 Juno is the first solar-powered spacecraft to work at Jupiter. NASA Science: Juno
  13. 99 Juno was still at work in 2026: on 1 May 2026 it photographed Thebe, one of Jupiter’s small inner moons. NASA Science: Juno stories · checked 27 Oct 2026
  14. 100 NASA’s Europa Clipper launched on 14 October 2024 and is due to reach Jupiter in April 2030. NASA Science: Europa Clipper · checked 27 Oct 2026
  15. 101 Europa Clipper is the first mission designed to make a detailed study of Europa. NASA Science: Europa Clipper
  16. 102 ESA’s Juice launched on 14 April 2023 and is due to reach Jupiter in July 2031, to study Ganymede, Europa and Callisto. ESA: Juice factsheet · checked 27 Oct 2026
  17. 103 Juice is planned to finish with an orbital tour of Ganymede. ESA: Juice factsheet