Jupiter’s Moons: Facts About the Largest Jovian Moons

 Jupiter has 80 moons in total, 57 are official and an extra 23 are awaiting affirmation and naming by the Worldwide Astronomical Union. 

4 of Jupiter‘s moons: Io, Europa, Ganymede and Callisto — often called the Galilean moons — had been the primary celestial objects to be found orbiting an object apart from the sun or Earth when Galileo Galilei first noticed them in 1610. 

Most of Jupiter’s moons are small, with about 60 of the satellites measuring lower than 6.2 miles (10 kilometers) in diameter. Unusually, the outer moons orbit in the opposite direction (opens in new tab) to which Jupiter spins, suggesting they might have been captured by Jupiter’s gravitational subject after the preliminary system was fashioned. 

Associated: The 10 weirdest moons in the solar system

Jupiter’s official moons: Names and discovery dates

Here’s a record of all 57 official moons (opens in new tab) of Jupiter together with particulars on their discovery, in accordance with NASA. There are nonetheless 23 moons awaiting affirmation by the Worldwide Astronomical Union. 

Adrastea: Found in July 1979 by the Voyager science workforce. 

Aitne: Found on 9 December 2001 by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna throughout observations on the Mauna Kea Observatory, Hawaii. 

Amalthea: Found on September 9, 1892, by American astronomer Edward Emerson Barnard.

Ananke: Found on September 28, 1951, by American astronomer Seth Barnes Nicholson from {a photograph} made utilizing the 100-inch (2.5 meter) Hooker telescope on the Mount Wilson Observatory in California.

Aoede: Found on February 8, 2003, by Scott S. Sheppard, David C. Jewitt, Jan T. Kleyna, Yanga R. Fernandez, and Henry H. Hsieh throughout observations on the Mauna Kea Observatory in Hawaii.

Arche: Found on October 31, 2002, by Scott S. Sheppard on the Mauna Kea Observatory in Hawaii. 

Autonoe: Found on December 10, 2001, by Scott S. Sheppard, David C. Jewitt, and Jan T. Kleyna on the Mauna Kea Observatory in Hawaii.

Callirrhoe: Found on October 19, 1999, by Jim V. Scotti, Timothy B. Spahr, Robert S. McMillan, Jeffrey A. Larsen, Joe Montani, Arianna E. Gleason, and Tom Gehrels from observations made with the 36-inch telescope on Kitt Peak. The invention was made throughout a course of observations by the Spacewatch program of the College of Arizona.

Callisto: Found on January 7, 1610, by Italian scientist Galileo Galilei.

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Carme: Found on July 30, 1938, by Seth Barnes Nicholson throughout observations made with the 100-inch (2.5 m) Hooker telescope on the Mount Wilson Observatory in California.

Carpo: Found on February 26, 2003, by a workforce of astronomers from the College of Hawaii’s Institute for Astronomy led by Scott S. Sheppard. The invention was made utilizing the 12-ft. (3.6-m) Canada-France-Hawaii telescope on the Mauna Kea Observatory in Hawaii.

Chaldene: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yange R. Fernandez, and Eugene Magnier at an observatory on Mauna Kea in Hawaii.

Cyllene: Found on February 9, 2003, by Scott S. Sheppard and his workforce from the College of Hawaii on the Mauna Kea Observatory, Hawaii.

Dia: Found on December 5, 2000, by Scott S. Sheppard, David Jewitt, Y. R. Fernandez, and G. Magnier with the two.2-m reflector on Mauna Kea, Hawaii. 

Eirene: Found on February 6, 2003, by Scott S. Sheppard, David C. Jewitt, and Jan T. Kleyna on the Mauna Kea Observatory in Hawaii. 

Elara: Found on January 5 1905, by American astronomer Charles Dillon Perrine whereas pictures taken with the Crossley 36-inch (0.9 meter) reflector of the Lick Observatory on Mount Hamilton on the College of California, San Jose.

Erinome: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez and Eugene Magnier on the Mauna Kea Observatory in Hawaii.

Ersa: First noticed in 2017, the moon’s discovery by Scott S. Sheppard and his workforce was introduced in July 2018. 

Euanthe: Found on December 11, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory in Hawaii.

Eukelade: Found on February 6, 2003, by Scott S. Sheppard on the Mauna Kea Observatory in Hawaii.

Eupheme: Found on March 4, 2003, by Scott S. Sheppard on the Mauna Kea Observatory in Hawaii

Euporie: Found on December 11, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory in Hawaii.

Europa: Found on January 8, 1610, by Italian scientist Galileo Galilei.

Eurydome: Found on December 9, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Ganymede: Found on January 7, 1610, by Italian scientist Galileo Galilei.

Harpalyke: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier on the Mauna Kea Observatory, Hawaii.

Hegemone: Found on February 8, 2003, by Scott S. Sheppard, David C. Jewitt, Jan T. Kleyna, Yanga R. Fernandez, and Henry H. Hsieh on the Mauna Kea Observatory, Hawaii.

Helike: Found on February 6, 2003, by Scott S. Sheppard on the Mauna Kea Observatory, Hawaii.

Hermippe: Found on December 9, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Herse: Found on February 27, 2003, by Brett J. Gladman, John J. Kavelaars, Jean-Marc Petit, and Lynne Allen.

Himalia: Found on December 3, 1904, by American astronomer Charles Dillon Perrine whereas pictures taken with the Crossley 36-inch (0.9 meter) reflector of the Lick Observatory on Mount Hamilton on the College of California, San Jose.

Io: Found on January 8, 1610, by Italian scientist Galileo Galilei.

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Iocaste: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier on the Mauna Kea Observatory, Hawaii.

Isonoe: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier on the Mauna Kea Observatory, Hawaii.

Kale: Found on December 9, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Kallichore: Found on February 6, 2003, by Scott S. Sheppard on the Mauna Kea Observatory, Hawaii.

Kalyke: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier on the Mauna Kea Observatory, Hawaii.

Kore: Found on February 8, 2003, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Leda: Found on September 14, 1974, by American astronomer Charles Thomas Kowal throughout observations of plates taken from Sept. 11 via 13, 1974 on the Palomar Observatory, California.

Lysithea: Found on July 6, 1938, by American astronomer Seth Barnes Nicholson with the 100-inch (2.5 m) Hooker telescope on the Mount Wilson Observatory, California.

Megaclite: Found on November 25, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene A. Magnier on the Mauna Kea Observatory in Hawaii.

Metis: Found in March 1979 by the Voyager science workforce.

Mneme: Found on February 9, 2003, by Scott S. Sheppard and Brett Joseph Gladman on the Mauna Kea Observatory, Hawaii.

Orthosie: Found on December 11, 2001, by Scott S. Sheppard, Yanga R. Fernandez and David C. Jewitt on the Mauna Kea Observatory, Hawaii.

Pandia: First noticed in 2017, the moon’s discovery by Scott S. Sheppard and his workforce was introduced in July 2018. 

Pasiphae: Found on January 27, 1908, by British astronomer Philibert Jacques Melotte with the Greenwich Observatory’s 30-inch Cassegrain telescope.

Pasithee: Found on December 11, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Philophrosyne: Found in April 2003 by Scott S. Sheppard on the Mauna Kea Observatory in Hawaii.

Praxidike: Found on November 23, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier on the Mauna Kea Observatory, Hawaii.

Sinope: Found on July 21, 1914, by American astronomer Seth Barnes Nicholson throughout observations of photographic plates taken with the Lick Observatory’s 36-inch (0.9 meter) telescope in California. 

Sponde: Found on December 9, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Taygete: Found on November 25, 2000, by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier on the Mauna Kea Observatory, Hawaii.

Thebe: Found in 1980 by the Voyager science workforce investigating images captured by Voyager 1.

Thelxinoe: Found on February 9, 2003, by Scott S. Sheppard and Brett J. Gladman on the Mauna Kea Observatory, Hawaii.

Themisto: Found initially on September 30, 1975, by American astronomers Charles Thomas Kowal and Elizabeth Roemer. The little moon was then misplaced till 2000 when it was rediscovered by Scott S. Sheppard, David C. Jewitt, Yanga Roland Fernandez and Eugene A. Magnier throughout their seek for small irregular Jovian moons utilizing the 27-foot (8.3m) Subaru telescope and the 11.8-foot (3.6m) Canada-French-Hawaii telescope at Mauna Kea Observatories, Hawaii.

Thyone: Found on December 11, 2001, by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna on the Mauna Kea Observatory, Hawaii.

Valetudo: First noticed in 2017, the moon’s discovery by Scott S. Sheppard and his workforce was introduced in June 2018. 

Galilean moons: Jupiter’s greatest satellites

1. Ganymede  

Diameter: 3,270 miles (5,260 kilometers)

Jupiter’s moon Ganymede is the most important moon within the solar system, it’s even bigger than the planet Mercury. Additionally it is the one moon that we all know of to have its personal magnetic subject, which causes spectacular polar gentle exhibits — auroras. Moreover, the large moon may harbor a subsurface saltwater ocean which has been theorized to carry extra water than all of the water on Earth’s floor, according to NASA Science. (opens in new tab)  

2. Europa  

Diameter: 1,940 miles (3,100 km)

Europa is believed to have an iron core, rocky mantle and a floor of frozen water ice that sits atop an unlimited saltwater ocean. According to NASA (opens in new tab), the icy moon Europa is regarded as essentially the most promising place to search out an surroundings that would help life kinds past Earth. The theorized subsurface saltwater ocean may include twice as a lot water as Earth’s oceans mixed and have existed lengthy sufficient for all times to have probably begun and even advanced. 

3. Io

Diameter: 2,260 miles (3,640 km)

Essentially the most volcanically lively place within the solar system, Io is a outstanding world locked in a “tug-of-war” between Jupiter’s gravity and pulls from neighboring Galilean moons Europa and Ganymede. The turbid surroundings continually renews itself (opens in new tab), smoothing out craters with huge lakes of lava spewed from one of many lots of of volcanoes that blanket the panorama.  

4. Callisto 

Diameter: 2,995 miles (4,820 km)

Jupiter’s second-largest moon Callisto is the third-largest moon within the solar system. The moon’s floor is regarded as about 4 billion years old (opens in new tab), making it the oldest icy floor within the solar system. After being pummeled for4 billion years by impactors resembling meteors, it comes as no shock that Callisto additionally holds the document for essentially the most closely cratered physique within the solar system.  

Exploration of Jupiter and its moons

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The Jovian system is not any stranger to company. Since its first customer in December 1973 when NASA’s Pioneer 10 spacecraft carried out a flyby of the gas giant, Jupiter has attracted quite a few flybys and close encounters (opens in new tab) from trailblazing probes. Pioneer 11 made an in depth method a yr after Pioneer 10 in December 1974 and Voyager 1 and Voyager 2 flew previous Jupiter in 1979. 

But it surely wasn’t till NASA’s Galileo spacecraft approached the Jovian system in December 1995 that the gas giant lastly had a visitor keep for any important size of time. Galileo was the primary spacecraft to orbit Jupiter and made substantial discoveries concerning the gas giant and its moons. The spacecraft spent virtually eight years in Jupiter’s neighborhood, revealing its many secrets and techniques, from a attainable subsurface ocean on Jupiter’s icy moon Europa, to volcanoes on the moon Io. On the finish of its keep in September 2003, Galileo deliberately crashed into the gas giant to stop collisions and subsequent contamination with the Jovian moons. 

The NASA-ESA Ulysses mission used Jupiter for a few gravity-assist maneuvers in 1992 and 2004 whereas en path to the sun and NASA’s Cassini-Huygens spacecraft additionally paid Jupiter a quick go to whereas journeying to Saturn. Cassini made its shut method to Jupiter in December 2000 and picked up round 26,000 pictures of the gas giant within the course of. Then NASA’s New Horizons spacecraft known as in on Jupiter in February 2007 throughout its journey to Pluto and revealed spectacular nighttime auroras and lightning close to the planet’s poles. 

The Jovian system is at present being explored by NASA’s Juno mission which arrived in July 2016. Juno is barely the second spacecraft to orbit Jupiter and is busy investigating its composition, ambiance, gravity and magnetic subject. Juno goals to study extra concerning the origin and evolution of Jupiter and the solar system.

Subsequent on the roster to go to the Jovian neighborhood is ESA’s Jupiter Icy Moons Explorer, JUICE, attributable to launch in April 2023. The mission will discover Jupiter and three of its Galilean moons: Ganymede, Callisto and Europa. It is going to then be joined by NASA’s Europa Clipper mission, scheduled to launch October 2024. The mission will focus (opens in new tab) on Jupiter’s icy moon Europa and examine whether or not the unusual world harbors situations that would accommodate life. 

Learn how to see Jupiter’s moons for your self

With the best tools, it’s attainable to identify Jupiter and its 4 Galilean moons. Our visible planets guide tells you the place you could find the brightest planets that month and the most effective instances to view them. 

Jupiter can attain magnitude -2.94 at this brightness you’ll be able to spot the gas giant with the bare eye, a pair of binoculars or a small telescope. (On the magnitude scale utilized by astronomers, decrease numbers signify brighter objects. For instance, at its brightest, the planet Venus shines with a magnitude of about -4.6). You will want a very good pair of binoculars (at the very least x10 magnification) or a small telescope to see the Galilean moons. 

To seek out out the place and when to look out for Jupiter’s moons, we advocate utilizing skywatching apps like SkySafari or software program like Starry Night time. Our picks for the best stargazing apps could allow you to together with your planning.

For those who’re in search of a telescope or binoculars to look at Jupiter and its moons, our best telescopes for seeing planets information will help. We even have guides on the best binoculars deals and the best telescope deals, which can are available helpful when looking for a discount.  

Extra sources

Study extra about ESA’s JUICE mission to Jupiter’s icy moons with this video from ESA (opens in new tab). Learn extra about whether or not there might be life on Jupiter’s moons with this article by Jonathan O’Callaghan (opens in new tab) within the EU Analysis and Innovation journal Horizon. Do you suppose you have found a new moon or one thing else thrilling? The Worldwide Astronomical Union Report has a information to the most typical objects that you’ll have noticed in addition to data on officially report your findings (opens in new tab). 

Bibliography

ESA. Missions to Jupiter. ESA Science & Know-how. Retrieved October 21, 2022, from https://sci.esa.int/web/juice/-/59909-missions-to-jupiter (opens in new tab)

NASA. Callisto. NASA. Retrieved October 21, 2022, from https://solarsystem.nasa.gov/moons/jupiter-moons/callisto/in-depth/ (opens in new tab)

NASA. Europa Clipper. NASA. Retrieved October 21, 2022, from https://www.jpl.nasa.gov/missions/europa-clipper (opens in new tab)

NASA. Io. NASA. Retrieved October 21, 2022, from https://solarsystem.nasa.gov/moons/jupiter-moons/io/in-depth (opens in new tab)

NASA. Jupiter moons. NASA. Retrieved October 21, 2022, from https://solarsystem.nasa.gov/moons/jupiter-moons/overview (opens in new tab)

NASA. Europa. NASA. Retrieved October 21, 2022, from https://solarsystem.nasa.gov/moons/jupiter-moons/europa/overview/ (opens in new tab)

NASA. Ganymede. NASA. Retrieved October 21, 2022, from https://solarsystem.nasa.gov/moons/jupiter-moons/ganymede/overview/ (opens in new tab)

Williams, M. (June 10, 2015). The moons of Jupiter. Phys.org. Retrieved October 21, 2022, from https://phys.org/news/2015-06-moons-jupiter.html (opens in new tab)