How Many Moons Does Jupiter Have? 95+ Confirmed (2024)

Jupiter’s moon count is a moving target — and that’s exactly what makes it fascinating. As of 2024, the International Astronomical Union (IAU) has confirmed at least 95 moons orbiting the gas giant, but the number changes every few years as new surveys uncover smaller and smaller moons.

Jupiter’s confirmed moons (2024): 95+ | Largest moon: Ganymede (5,268 km) | Smallest known moon: ~1 km diameter | Year of first moon discovery: 1610 | Most recent moon discoveries: 2023

How many moons does Jupiter have?

Current official count (2024)

According to the IAU, Jupiter now has 95 recognized moons. NASA’s official moon count page states: “Jupiter has between 80 and 95 moons, but neither number captures the complexity of the system.” That statement hints at the ongoing process of discovery: many small, kilometer-sized objects are waiting for confirmation.

The Galilean moons

Four moons dominate: Io, Europa, Ganymede, and Callisto. Galileo Galilei discovered them in 1610, and they remain the largest and most studied. Ganymede, at 5,268 km across, is bigger than Mercury.

How the count has changed over time

For over two centuries after Galileo, only these four were known. Then in 1892, Edward Emerson Barnard spotted Amalthea. The Voyager flybys in 1979 added more. A surge in 2003 brought the count past 60. Ground-based telescopes, especially the Canada-France-Hawaii Telescope, pushed it over 90 in 2018–2023.

Which planet has 274 moons?

Saturn’s confirmed moon count

Saturn leads the solar system with 274 confirmed moons as of 2024, per Wikipedia’s moons of Saturn page (citing IAU data). The total keeps rising because Saturn’s bright rings and large Hill sphere allow detection of many small moonlets.

Why Saturn’s count has increased recently

Deep surveys like the Subaru Telescope’s campaign have found tiny moonlets less than 5 km across. Some of these are probably captured fragments from collisions or disruptions of larger bodies.

Comparison with Jupiter’s moon count

Jupiter has 95 moons, Saturn 274 — but Jupiter’s four Galilean moons are far larger than any of Saturn’s regular moons. The two gas giants illustrate different formation histories: Jupiter’s system grew more violent, while Saturn’s may have accreted more debris.

Who has 0 moons?

Mercury and Venus

Mercury and Venus have no natural satellites. That’s because they are too close to the Sun — the Sun’s gravity destabilizes any potential moon’s orbit. Earth has one moon, Mars has two small irregular ones (Phobos and Deimos).

Why some planets lack moons

Formation theory says moons arise from spinning disks of debris or from captured objects. For Mercury and Venus, the Moon-forming collision scenario didn’t play out, and any captured rocks would have been yanked away by solar tides.

The definition of a moon

A moon is a natural satellite that orbits a planet, dwarf planet, or other minor planet. The IAU has formal criteria, but the line between a moon and a ring particle gets blurry for sub-kilometer objects.

How many moons does Uranus have?

Uranus’s known moons

Uranus has 27 confirmed moons, all named after characters from Shakespeare and Pope. NASA’s Uranus moons page lists them.

Names and characteristics

The five major moons — Miranda, Ariel, Umbriel, Titania, Oberon — range from 470 to 1,580 km. Many of the 22 smaller moons are irregular, captured bodies.

How Uranus compares to other gas giants

Uranus has fewer moons than Jupiter (95) and Saturn (274) but more than Neptune (16). Its moon system is tilted 98° because Uranus itself rolls on its side.

Did Jupiter save Earth in 1994?

The Shoemaker-Levy 9 comet impact

In July 1994, Comet Shoemaker-Levy 9 broke apart and slammed into Jupiter’s southern hemisphere. The event was widely observed by astronomers and amateurs alike.

Jupiter’s gravitational influence

Jupiter’s immense gravity captured the comet, broke it into fragments, and ultimately pulled them into its atmosphere. This is often called the “cosmic shield” effect.

What happened during the 1994 event

The fragments left dark scars in Jupiter’s clouds that persisted for months. Wikipedia’s account details the timeline. Without Jupiter, the comet might have crossed Earth’s path in later years.

“Jupiter’s gravity shepherds many small objects away from the inner solar system,” says Scott Sheppard of the Carnegie Institution, a leading discoverer of Jovian moons. “It’s a gravitational vacuum cleaner.”

The NASA Science Mission Directorate puts it this way: “Jupiter’s immense size and mass make it a critical player in the dynamics of the solar system.”

Timeline of discoveries

• 1610 — Galileo Galilei discovers 4 largest moons (Io, Europa, Ganymede, Callisto) — Wikipedia
• 1892 — Edward Emerson Barnard discovers Amalthea (first moon since Galileo)
• 1979 — Voyager 1 reveals additional small moons and rings — NASA Voyager
• 2003 — Discovery of 23 new moons, pushing count over 60
• 2018–2023 — Surge in discoveries from ground-based surveys; Jupiter’s count passes 90
• 2024 — Current known count: 95 confirmed by IAU, with more candidates waiting confirmation

“We’re finding that there are many small, irregular moons that are probably fragments from larger parent bodies that broke up,” said Scott Sheppard in a press release after the 2023 discoveries.

While Jupiter’s 95 confirmed moons make it a satellite giant, the ringed planets 274 moons puts Saturn far ahead in the solar system moon race.

Frequently Asked Questions

More planet comparisons

For a deeper look at another intriguing planet, read the article on Saturn Devouring His Son: Goya’s Dark Myth Explained. And for another science explainer, check Is Nuclear Energy Renewable or Nonrenewable? Key Facts Explained.

Moon count comparison table

The table below shows how Jupiter’s moon system stacks up against other outer planets.

The catch: Numbers from the IAU and NASA vary by a few because confirmation of candidate moons can lag behind discovery.

External references

• NASA’s Jupiter moons page
• Wikipedia: Moons of Jupiter
• IAU moon naming
• NASA Solar System Moons
• Space.com: Jupiter’s Moons
• Wikipedia: Moons of Saturn
• Wikipedia: Moons of Uranus
• Wikipedia: Moons of Neptune
• NASA Voyager mission
• Carnegie Institution for Science