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Jupiter: Quick Facts

Larry Slawson received his Master's Degree from UNC Charlotte in 2018. He has a keen interest in biology, chemistry, and astronomy.

The massive gas giant known as Jupiter

The massive gas giant known as Jupiter

Planetary Properties of Jupiter

  • Orbital Semimajor Axis: 5.20 Astronomical Units (778.4 Million Kilometers)
  • Orbital Eccentricity: 0.048
  • Perihelion: 4.95 Astronomical Units (740.7 Million Kilometers)
  • Aphelion: 5.46 Astronomical Units (816.1 Million Kilometers)
  • Mean/Average Orbital Speed: 13.1 Kilometers Per Second
  • Sidereal Orbital Period: 11.86 Years (Tropical)
  • Synodic Orbital Period: 398.88 Days (Solar)
  • Orbital Inclination to the Ecliptic: 1.31 Degrees
  • Greatest Angular Diameter (As Viewed From Earth): 50”
  • Overall Mass: 1.90 x 1027 Kilograms (317.8 of Earth’s Overall Mass)
  • Equatorial Radius: 71,492 Kilometers (11.21 of Earth’s Equatorial Radius)
  • Mean/Average Density: 1,330 Kilograms Per Meter Cubed (0.241 of Earth’s Average Density)
  • Surface Gravity: 24.8 Meters Per Second Squared (2.53 of Earth’s Surface Gravity)
  • Escape Speed/Velocity: 59.5 Kilometers Per Second
  • Sidereal Rotation Period: 0.41 Days (Solar)
  • Axial Tilt: 3.08 Degrees
  • Surface Magnetic Field: 13.89 of Earth’s Surface Magnetic Field
  • Magnetic Axis Tilt (Relative to Rotation Axis): 9.6 Degrees
  • Overall Surface Temperature: Approximately 124 Kelvins (-236.47 Degrees Fahrenheit)
  • Total Number of Moons: 67 in Total (Possibly More)
Internal structure of Jupiter

Internal structure of Jupiter

Quick Facts

  • Jupiter is the fifth planet from the Sun, and the fourth brightest object visible in our solar system (after the Sun, the Moon, and Venus). It is also one of only five planets that are visible to the naked eye.
  • Scholars believe that the Babylonians are the first people to have recorded a sighting of Jupiter in the night sky. This occurred during the 7th and 8th centuries. Jupiter derives its name from the Roman god, who was equivalent to Zeus in Greek mythology.
  • Jupiter has a rapid rotation rate as it orbits the Sun. As a result of this rapid spin, Jupiter’s days are incredibly short (approximately nine hours and fifty-five minutes). The rapid rotation also gives the planet a “flattened” appearance. Despite a rapid day/night cycle, it takes Jupiter approximately 11.8 years (Earth years) to make a full orbit of the Sun.
  • Jupiter’s atmosphere is incredibly thick and is comprised of numerous cloud belts and zones. Scientists believe that these zones are made up primarily of sulfur, hydrogen, and ammonia.
  • Many scientists believe that Jupiter’s interior is comprised of rock, hydrogen, and metal elements.
  • Similar to the planet Saturn, Jupiter maintains a thin network of rings that circle the planet. These rings are composed primarily of dust molecules, which are believed to have formed from comet and asteroid impacts. Jupiter’s rings are massive; beginning nearly 92,000 kilometers above its surface and stretching outwards to 225,000 kilometers from the planet. The rings range in thickness from two thousand to twelve thousand kilometers in width/diameter.
Jupiter's Galilean Moons

Jupiter's Galilean Moons

More Fun Facts

  • Out of all of Jupiter’s moons, Ganymede is the largest of the gas giant’s natural satellites. Ganymede is also the largest moon in our solar system, at nearly 5,268 kilometers in diameter. The moon is even larger than the planet Mercury.
  • Eight different spacecraft have performed flybys around Jupiter; these include the Pioneer, Voyager, Galileo, Cassini, Ulysses, Juno, and New Horizon spacecraft.
  • Currently, scientists have confirmed the existence of at least 67 moons that orbit the planet Jupiter. Scientists and astronomers have categorized these moons into three subgroups, including: inner moons; Galilean moons; and outer moons. Of these three groups, the Galilean moons are the largest of Jupiter’s moons, and were first discovered by Galileo Galilei in the early 1600s (Io, Europa, Ganymede, and Callisto).
  • Jupiter is the largest planet in our solar system, with a mass of around 1.90 x 1027 kilograms, a diameter of approximately 139,822 kilometers (approximately the diameter of eleven Earths, and a mass of 317 Earths).
  • Due to its axial tilt (approximately 3.13 degrees), Jupiter does not experience seasonal variations like Earth or Mars.
  • One of the most famous characteristics of Jupiter is its “Great Red Spot.” The spot is actually a large, supermassive storm that has been active for at least 300 years. To put the storm’s size into perspective, nearly three Earths would fit inside the Great Red Spot.
  • Jupiter’s magnetic field is one of the strongest in the solar system and is approximately fourteen times the strength of Earth’s magnetic field.
  • Jupiter is often described by scientists as the solar system’s “vacuum cleaner.” This is in reference to the great number of asteroids, comets, and meteors that are drawn toward Jupiter due to its tremendous gravitational pull. Jupiter, in total, experiences nearly 200 times the number of comet, meteor, and asteroid impacts experienced on Earth. In this way, Jupiter is often described as a shield for Earth and the inner planets, in that it directs thousands of objects away from the Earth’s orbit.

“Without Jupiter cleaning out the early solar system, the Earth would be pock-marked with meteor collisions. We would suffer from asteroid impacts every day. CNN studios would probably be a gigantic crater if it wasn’t for Jupiter.”

— Michio Kaku

Quotes about Jupiter

  • “Without Jupiter cleaning out the early solar system, the Earth would be pock-marked with meteor collisions. We would suffer from asteroid impacts every day. CNN studios would probably be a gigantic crater if it wasn’t for Jupiter.” —Michio Kaku
  • “We must believe then, that as from hence we see Saturn and Jupiter; if we were in either of the Two, we should discover a great many worlds which we perceive not; and that the Universe extends so in infinitum.” —Cyrano de Bergerac
  • “Weather forecast for Jupiter’s South Equatorial Belt: cloudy with a chance of ammonia.” —Heidi Hammel
  • “In awe, I watched the waxing moon ride across the zenith of the heavens like an ambered chariot towards the ebony void of infinite space, wherein the tethered belts of Jupiter and Mars hang, for ever festooned in their orbital majesty. And as I looked at all this I thought… I must put a roof on this toilet.” —Les Dawson
Infrared view of Jupiter

Infrared view of Jupiter

Planet or Star?

For several years, scientists debated whether Jupiter was actually a brown dwarf star or a planet. Although scientists now accept Jupiter as a planet (and not a star), it is possible that it could have become a small star in its infant years. This didn’t occur, however, because the planet lacked a suitable amount of mass (from dust and gas); It was impossible for nuclear fusion to ignite in its core. Nevertheless, Jupiter still maintains characteristics that are similar to dwarf stars, including a massive magnetic field, a core that radiates its own energy, an atmosphere full of hydrogen and helium, and a tremendous amount of gravitational pull.

Up-close view of Jupiter and one of its moons

Up-close view of Jupiter and one of its moons

Great Red Spot

Jupiter’s “Great Red Spot” remains one of the planet’s most well-known features, to date. The spot is actually an anticyclonic storm that is larger than the size of Earth. First spotted in 1665, the storm is located approximately 22 degrees south of Jupiter’s equator and five miles above Jupiter's surrounding cloud cover. The storm spins in a counterclockwise motion.

Although many mathematical models have indicated that the storm is a permanent feature of the planet, many astronomers have noted a decrease in Jupiter’s size since its initial observations in the 1800s. Whereas the storm was approximately 25,500 miles across (the late 1800s), the Voyager flybys indicated a size of 14,500 miles in 1979. Current observations indicate that the storm appears to be shrinking at a rate of 930 kilometers (or 580 miles) per year.

Additional spots have been located across Jupiter’s large atmosphere as well. In the early 2000s, a smaller “spot” was discovered near Jupiter’s Southern hemisphere. And in April of 2017, scientists discovered a “Great Cold Spot” across Jupiter’s thermosphere that is approximately 15,000 miles across and nearly 360 degrees (Fahrenheit) cooler than the surrounding atmosphere.


In closing, Jupiter remains one of the most fascinating objects in our solar system and galaxy at large. As more and more space missions are launched in the foreseeable future, it will be interesting to see what new information can be gleaned about this gas giant, its origins, and its impact on the solar system’s functionality.

Works Cited

Wikipedia contributors, "Jupiter," Wikipedia, The Free Encyclopedia, (accessed January 7, 2019).

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2019 Larry Slawson


Larry Slawson (author) from North Carolina on January 09, 2019:

@Liz You know, it’s funny you mentioned that... I was actually considering that possibility earlier haha. I may just do that before it’s over too.

Liz Westwood from UK on January 09, 2019:

I think you could bind your series together in a fact file book. It is interesting to read.

Larry Slawson (author) from North Carolina on January 08, 2019:

@Eric Haha, I’m glad you enjoyed! Yeah, I think Jupiter has been my favorite planet to study so far in this series. There are so many things that make it special and one of a kind in the solar system.

Eric Dierker from Spring Valley, CA. U.S.A. on January 08, 2019:

I will get back to you. My son and I are loving this series. How many moons and a storm bigger than earth and it has rings? This is an amazing one. No Way!!

Larry Slawson (author) from North Carolina on January 08, 2019:

@Pamela I’m glad you are enjoying them :) I’ve always been fascinated with astronomy. It’s amazing to think about all the planets, stars, and galaxies; and just how small Earth is, in the context of the universe at large.

Pamela Oglesby from Sunny Florida on January 08, 2019:

I have learned several facts about Jupiter that I did not know. I'm glad you are sharing your love of astronomy in your articles.