Facts About Jupiter: Revealing Information About the Monster in Our Solar System

Let’s start with some facts about Jupiter, the fifth planet from the Sun and the most enormous beast in the solar system. It’s a gas giant of immense size, with storms larger than Earth and about 90 moons. Jupiter captures our imaginations with its swirling gases and huge liquid hydrogen ocean. Come along as we explore this gas giant further.

Facts About Jupiter: Planetary Explorations

Before we get too far into the facts about Jupiter, let’s delve into how we know all this information. Jupiter is one of the most explored planets in our solar system.

James Webb’s Findings on Jupiter

The James Webb Space Telescope continues astounding scientists with its extraordinary views of Jupiter. See one of Webb’s most amazing composite Jupiter images below. It is a compilation of images using red, yellow-green, and cyan filters on the NIRCam.

The red filter shows the planet’s auroras above both poles. The yellow-green filter lets you see swirling hazes near both poles. And the blue filter shows light reflected from the planet’s clouds. Finally, the Great Red Spot and other clouds reflect sunlight and appear white in color.

 

Image Credit: NASA, CSA, ESA, and the Jupiter ERS Team. Processing: Citizen Scientist Judy Schmidt

Juno Mission

The Juno spacecraft launched from Cape Canaveral on August 5, 2011. It began its first 53-day Jupiter orbit on July 5, 2016, and should make 37 complete orbits during its mission. In April 2023, Juno completed its 50th close pass-by.

In addition, scientists expect Juno to burn up in the planet’s atmosphere at the end of its mission, projected for September 2025.

Juno’s stated mission is to understand the following five items better.

• How the atmosphere formed through measuring oxygen and nitrogen
• Deep atmosphere variations
• The magnetic field structure
• The planet’s gravity field and the distribution of its internal mass
• The three-dimensional aurorae and polar magnetosphere

Check out this February 17, 2020, southern hemisphere Juno image compilation. It comes from four JunoCam images assembled by Kevin M. Gill.

Other Jupiter Explorations and Fly-Bys

Galileo is the only spacecraft besides Juno that traveled explicitly to Jupiter. It orbited the planet, dropping a probe into the atmosphere.

Some fly-bys include the following spacecraft.

• Voyager 1’s nearest approach March 5, 1979: 19,000 images and many measurements
• Voyager 2’s nearest fly-by July 9, 1979: 33,000 images of the planet and the five largest moons
• Pioneer 10: March 2, 1972 to January 23, 2003. Scheduled for a 21-month mission that lasted 30 years.
• Pioneer 11 flew by Jupiter on December 3, 1974
• Cassini: The closest Jupiter approach occurred on December 29, 2000, approximately 6.2 million miles (10 million kilometers) away. Over six months, Cassini gained 26,000 images and provided one of the most comprehensive studies of Jupiter. 
• New Horizons: Fly by on the way to Pluto and Kuiper Belt, with the closest approach to Jupiter on February 28, 2007. The spacecraft gathered data on Jupiter’s rings, atmosphere, and moons for four months.

Facts About Jupiter: The Largest World In Our Solar System

Now that we’ve established how scientists come to know so many facts about Jupiter let’s dive into some of them. First, let’s talk about just how enormous the fifth planet from the Sun is.

Jupiter And Earth Compared

Jupiter is so enormous that it is twice as massive as every other Solar System combined. Yes, combined!

The gas giant is about eleven times wider than Earth, with 318 times its mass. So if Earth were a nickel or a grape, Jupiter would look like a basketball next to it.

Earth Radius	Jupiter Radius
3,958.8 miles (6,371 kilometers)	43,440.7 miles (69,911 kilometers)

If we look at the sizes of Jupiter and Earth another way, the larger planet’s centuries-old raging storm is more extensive than our home planet. Yes, the Great Red Spot is 1.3 times wider than Earth. So if our planet fits into Jupiter’s storm, you start to get a better idea of just how enormous Jupiter is. 

Try imagining Earth inside the Great Red Spot seen in Jupiter’s southern hemisphere below.

Does Jupiter Have Earth-sized Moons?

In addition to Jupiter’s storm being larger than Earth, are its moons also bigger? Jupiter’s Galilean Moons: Europa, Io, Ganymede, and Callisto, are its largest natural satellites. But even though all four are more significant than our Moon, they are smaller than our home planet.

So Jupiter is a gigantic planet, but it does not have Earth-sized moons.

Jupiter And The Sun Compared

Even though Jupiter dwarfs every planet in the Solar System, it doesn’t hold a candle to the size of our Sun. In fact, the Sun has almost ten times Jupiter’s radius. So you can see that the two aren’t anywhere close in size.

Jupiter Radius	Sun Radius
43,440.7 miles (69,911 kilometers)	432,450 miles (696,000 kilometers)

Facts About Jupiter: Jupiter’s MakeUp

While Jupiter is smaller than Sun by far, the gas giant has a similar composition. Both are made mostly of helium and hydrogen. Jupiter is a massive planet, but it contains light elements.

Scientists think hydrogen gas gets compressed into a liquid by increasing temperature and pressure deep within Jupiter’s atmosphere. That creates the solar system’s largest ocean, a liquid hydrogen one instead of water like on Earth.

In addition, the pressure intensifies closer to the planet’s center. It becomes so great that hydrogen atoms squeeze off electrons, causing the liquid to conduct in the same way metals do electrically. Then the planet’s fast rotation drives electrical currents in the same area to generate Jupiter’s magnetic field.

Scientists still hope to learn whether Jupiter’s central core is solid or is an intensely-hot, murky soup. They believe temperatures at the planet’s center might reach 90,032 degrees Fahrenheit (50,000 degrees Celsius.) And they think the core likely consists of quartz-like silicate and iron materials.

To wrap it up, Jupiter’s makeup is similar to the Sun’s. It has a giant hydrogen ocean, intense pressures, a strong magnetic field, and a crazy hot center that might look like molten quartz. Now that’s a fun fact about Jupiter!

Facts About Jupiter: The Eye of Jupiter

Because Jupiter, like the Sun, is made of helium and hydrogen, it has no solid surface. And that makes the planet one enormous storm factory. Contrast that scenario with Earth, where cyclones and hurricanes lose some of their power once they leave the oceans and make landfall.

The Eye of Jupiter is also known as the Great Red Spot. And it is the best-known cyclone in the Solar System! It is trapped between two of the planet’s jet streams and is actually an anticyclone. That means it rotates opposite Earth’s giant storms around a high atmospheric center.

Facts About Jupiter: Jupiter’s Eye Size

The Great Red Spot is 1.3 times larger than Earth, with storm roots extending 200 miles up into its atmosphere. Earth’s cyclones generally extend only nine miles from their tops to bottoms. The difference is staggering, especially when you consider the winds’ intensities.

A Category 5 Earth hurricane sustains winds at 157 miles per hour and higher. But the Eye of Jupiter has consistent 400-mile-per-hour winds. Those speeds on Earth would destroy cities as we know them.

How Long Has the Eye of Jupiter Existed?

Giovanni Cassini made thirteen documented observations of Jupiter in 1665, noting the Eye of Jupiter. But the following known observation came almost two hundred years later when Samuel Schwabe made a detailed drawing of the storm in 1831. 

Later, C.W. Pritchett observed the Great Red Spot in 1878. And since that time, there has been at least one annual recording of the storm through telescope observation. Below you’ll see a JunoCam image processed to increase color saturation. Wouldn’t the early observers love seeing this incredible view of the Eye of Jupiter?

The July 20, 2019, original image came as the Juno spacecraft flew by the planet for the 21st time. Juno flew approximately 27,000 miles (43,000 kilometers) above the top of Jupiter’s clouds.

Will the Eye of Jupiter Die Out?

Scientists don’t know exactly how long the Great Red Spot has existed, only how long humans have observed it. But they do know how it continues changing. Images and data from the planet’s many fly-bys and missions help catalog the changes.

For example, images from the Voyagers and Galileo missions showed darkness around the storm. And that indicated there weren’t a lot of clouds surrounding it for sunlight to reflect off of. However, Webb’s images now show brighter cloud regions.

Scientists also know that the Eye of Jupiter was three times Earth’s size, compared to 1.3 times its current size. But while the storm’s diameter is shrinking, it is also growing taller. They believe the storm’s winds pull it up into the atmosphere in the same way that clay on a potter’s wheel elongates as it spins and you press inwards.

In 2019, Juno observed “flecks” of the Great Red Spot getting pulled into neighboring clouds. And while some reports have the storm dissipating in the next twenty or so years, the fact is that scientists just don’t know for sure when it might die out.

Facts About Jupiter: Giant Polar Cyclones

The Great Red Spot isn’t the only major storm on Jupiter. There are also multiple ridiculously large cyclones at both of the planet’s poles. And what’s even odder is that the storms arrange themselves into polygonal shapes.

Eight cyclones are forming an octagon at Jupiter’s north pole, while the south pole has a pentagon of five storms. Juno data shows that the storms stay in the exact locations. However, like hurricanes on Earth, they want to travel closer to the pole. But other storms, presiding over the poles, push the cyclones back and hold them in their polygonal structures.

Now, if you’ve learned one fact about Jupiter, it’s that it does everything big. So each polar cyclone would stretch across the U.S. from the top of North Dakota to Texas’ southern border.

Try to wrap your head around this Jupiter factoid: Eight cyclones circle the main one at the north pole, each with sizes ranging from 2,500 to 2,900 miles (about 4,000 to 4,600 kilometers). That’s enormous!

The wild colors in the Juno image below come from combining multiple images to create this view. But you can vividly see the storms circling Jupiter’s north pole.

How Many Moons Does Jupiter Have?

Jupiter has between 80 and 95 known moons, and scientists regularly find more natural satellites. The planet’s enormous size draws thousands of objects into its orbit. And the discoveries come so quickly now that the International Astronomical Union (IAU) no longer gives the small moons mythological names. Only if the satellite holds significant scientific interest will it get a name instead of a designation.

The Galilean Moons

Galileo Galilei, an Italian astronomer, who discovered Jupiter’s biggest moons in 1610. But, like with many discoveries, a German astronomer also saw the moons around that time. However, since Simon Marius didn’t publish his observations, the credit (and naming convention) went to Galileo.

Before delving into the smaller ones, let’s explore some facts about Jupiter’s larger moons, seen in the composite image below. Notice Jupiter’s Great Red Spot in addition to the moons in the following order: Io, Europa, Ganymede, and Callisto.

Ganymede

Ganymede is the largest of Jupiter’s moons and the solar system’s largest moon. It’s even more significant in size than Mercury and the dwarf planet Pluto. Scientists believe an underground saltwater ocean has more water than all of Earth’s surface water combined.

Additionally, this colossal moon is the only known satellite with its own magnetic field. A charged particle region like it surrounds Earth and other planets, but Ganymede is the first moon found to have one. As a result, the moon experiences auroras around its poles. These glowing gas ribbons are similar to what humans see around Earth’s poles.

Another remarkable fact about Jupiter’s most giant moon is that its magnetosphere creates sounds like planets do. Scientists say it sounds like hissing static or a soaring whistle. But Ganymede’s “song” means the moon has the first magnetosphere within a magnetosphere (Jupiter’s) in the solar system.

Check out this JunoCam image of Ganymede from only 645 miles (1,038 kilometers) away. The June 7, 2021, flyby brought the spacecraft closer to the moon than any other craft in over 20 years.

Callisto

Jupiter’s second-largest moon, Callisto, is also the solar system’s third-largest. It is almost as big as the planet Mercury. In addition, Callisto’s rocky and icy surface has more craters than any other solar system object.

One day on Callisto lasts about 17 Earth days, and that’s also the same amount of time it takes the moon to orbit Jupiter.

Callisto bored scientists for years since it didn’t seem to have much going on beyond the crater-covered surface. But Galileo spacecraft data indicated the moon potentially had a subsurface ocean, which helped engage astronomers with the satellite again. Scientists aren’t sure if there is or ever was an underground ocean, but Callisto’s interior could consist of icy layers mixed with rock and metal.

While the moon’s surface shows uniform craters, as you can see below, its brightness and colors are not uniform. Astronomers think the brighter areas represent ice, while the darker areas show where the ice eroded.

Io

Jupiter’s third-largest moon is Io.

Both Voyagers 1 & 2 reported data showing active volcanism on Jupiter’s moon, Io. And the discovery surprised astronomers since these were the first active volcanoes found outside of Earth. Hundreds of erupting volcanoes are on the moon at any given time, forcing sulfurous gases and molten lava into the atmosphere.

The image below comes from NASA’s Galileo spacecraft. It shows the moon, which is locked in a never-ending game of tug-of-war between Jupiter’s gravity and those of its neighboring moons. Io succumbs to a distorted orbit that causes it to stretch and flex as it makes its way around its planet. But that flexing creates intense heat and friction in the moon’s center, causing volcanic eruptions at the surface.

Europa

The smallest of the Galilean Moons, Europa, is about 90% the size of Earth’s Moon. So it would look about the same to us if it took our Moon’s place. However, Europa has an icy surface, reflecting sunlight 5.5 times brighter than our Moon. So while we might not notice the size difference between the two moons, our nights would undoubtedly become lighter.

Furthermore, Europa mainly consists of silicate rock with a water-ice crust. And scientists think it has an iron and nickel core. Its thin atmosphere consists mainly of oxygen, but the streaky surface is what gives Europa its eyeball-like appearance.

But one of the most astonishing facts about Jupiter’s sixth-closest moon is its vast saltwater ocean. Even larger than Ganymede’s subterranean ocean, Europa has about twice as much water as Earth beneath its icy crust.

Look below to see blocks in Europa’s crust that scientists think broke apart and then “rafted” into different positions. They say the features provide geologic evidence of the existence of an underground ocean. They believe the ocean is still present when combining this evidence with geologic data proving a magnetic field’s presence.

Jupiter’s Smaller Moons

Can Life Exist on Jupiter’s Moons?

Scientists believe that Europa holds the best possibility for life to exist. However, because of their potential subterranean oceans, Ganymede and even pockmarked Calisto could have faint possibilities for hosting living organisms, both now or in the past.

Europa has abundant liquid water, and combined with the correct chemical elements and energy, it definitely holds enough potential to warrant further data collection. Astrobiologists say life’s building blocks, namely hydrogen, carbon, oxygen, nitrogen, sulfur, and phosphorus, exist on Europa.

But beyond water and the correct elements, life requires energy. We get ours from the Sun through photosynthesis, which converts the Sun’s light into energy. Then eating plants transfers the energy to living beings.

Life on Europa would exist underneath its icy surface where sunlight doesn’t reach. Additionally, life couldn’t exist on the moon’s surface because of the radiation coming from Jupiter. But the radiation could create the energy needed for life below the moon’s surface.

Scientists think Europan life might take the form of microbes if it indeed exists. However, the prospect of life on Jupiter’s moon is exciting because if it exists in two places around the same central star, it might mean more life exists throughout the universe.

Does Jupiter Have Rings?

Jupiter does have rings, but they are very faint. A million times more faint than Jupiter itself, to be exact. And astronomers didn’t even know about the rings until the Voyager 1 images surprised them.

Since Jupiter’s rings consist of tiny, dark cosmic particles, you can’t see them well until they get backlit by the Sun. Spacecraft Galileo data indicates the rings formed when meteoroids crashed into Jupiter’s smaller moons, creating dust particles.

Released in August 2022, the James Webb NIRCam captured images of Jupiter’s rings and two of its moons in orange and cyan filters. Citizen scientist Judy Schmidt helped process them.

Facts About Jupiter: Distance From the Sun

Jupiter has an average distance from the Sun of 484 million miles (778 million kilometers.) In addition, it is 5.2 AU from the Sun. As a reminder, one AU or astronomical unit is the measured distance from Earth to the Sun, making for an easy measurement method in space.

Sunlight takes about 43 minutes to travel through space to reach Jupiter. By contrast, it takes only eight and ⅓ minutes to reach Earth.

Facts About Jupiter: How Long Is a Day On Jupiter?

Jupiter takes about 10 hours to rotate once on its axis for the solar system’s shortest day! Just five hours of daylight and five hours of darkness make up a Jovian day. However, it takes the gas giant approximately twelve Earth years to make a trip around the Sun. So one Jovian year is about 4,333 Earth days.

In addition, the planet spins nearly upright with a tilt of only three degrees. So Jupiter doesn’t have the extreme seasonal changes that some other planets, like sideways-rotating Uranus, experience.

Facts About Jupiter: Popular Fiction

Jupiter is a massive planet with a gas giant of a personality, and its superstardom shines through in popular fiction. Jupiter takes the starring role in many Hollywood movies and features in the background of quite a few more.

Here are a few movies featuring Jupiter and its moons.

• Jupiter Ascending, from the Wachowski siblings
• A Trip to Jupiter (1909)
• The Wandering Earth
• Men in Black: Will Smith’s character had a teacher from one of Jupiter’s moons.
• Power Rangers
• Halo
• Cloud Atlas
• Europa Report
• Futurama

Jupiter starred in its share of fiction books also. Titles like Ben Bova’s Jupiter share their spotlight with the gas giant.

Facts About Jupiter: Wrapping It Up

Jupiter is not only the fifth planet from the Sun, but it is the most significant world in the solar system. This gas giant has short ten-hour days and 12-Earth-year long years.

Made of helium and hydrogen, Jupiter is a massive but light world. And it even has an enormous liquid hydrogen ocean, a powerfully intense magnetic field, and a hellish-ly hot core.

But those aren’t even the most fun facts about Jupiter. It also has between 80 and 95 moons, the largest four named after Galileo. And just when you think it couldn’t get any better, three of those four have the potential for some type of life form. Europa has the best chance of life within its saltwater subterranean oceans underneath its icy crust.

And while astrobiologists can’t yet prove life on one of Jupiter’s moons, they still have enough fascinating facts to interest scientists for a long time to come. 

In addition to compelling moons, faint rings surround Jupiter. And scientists believe they likely form from flying dust when the planet’s smaller inner moons get pummeled with asteroids or meteorites.

Jupiter is full of mysteries, and expeditions to and near the planet continue to provide answers. The spacecraft Juno returns tens of thousands of images and data points and still has at least two more years of exploration. Who knows what new facts about Jupiter it will uncover?