Facts about the planet Jupiter

The greatest facts about Jupiter, the King of the Solar System

Jupiter is the undisputed King of the Planets. It’s a gas giant, its huge mass made up of hydrogen and helium gas.

Jupiter's upper atmosphere is streaked by dark belts and white zones – streams of clouds that blow in alternating directions around the planet.

Caught between these are several huge storms. The largest of these, the Great Red Spot, has been raging for at least 150 years and could easily swallow the entire Earth.

Yet these features only make up the top few hundred km of Jupiter’s atmosphere.

It’s thought that some kind of solid core lies at Jupiter’s heart, as the density of the planet would be incredibly intense, but no one is sure exactly what this core would look like or what it’s made of.

Jupiter's huge mass influences the entire Solar System, particularly the asteroid belt where the constant tug of the planet has created openings in the belt known as the Kirkwood gaps.

Here is our rundown of the greatest facts about Jupiter.

Facts about Jupiter in brief

• Diameter: 142,984km at equator (11.2 times Earth), 133,708km through poles (10.5 times Earth)
• Mass: 1898 trillion trillion kg (318 times Earth)
• Distance from the Sun: 778.6 million km (5.27 AU)
• Length of day: 9.9 hours
• Length of year: 11.9 years
• Number of moons: 95
• Average temperature: -110ºC
• No of spacecraft visitors: 9
• Type of planet: Gas giant

How hot is Jupiter?

Jupiter's average temperature is thought to be roughly –145°C (–234 degrees Fahrenheit), however this is just the temperature of the planet's clouds.

Jupiter's core temperature could be as hot as 24,000°C (43,000 degrees Fahrenheit).

For more facts about Jupiter and its temperature, read this article.

How big is Jupiter?

Jupiter is in fact the largest planet in the Solar System, measuring 142,984 km in diameter around the equator, 11.2 times that of Earth.

From pole to pole, however, the gas giant measures just 133,708km (10.5 times Earth).

This is because Jupiter's enormous mass and rapid spin mean that it balloons out at the equator, making the planet look like it's been squashed at the poles; a shape known as an 'oblate spheroid'.

For a demonstration of this, watch our video How does spinning change the shape of planets?

The planet is so large that all the other planets of the Solar System would easily fit within its volume.

Jupiter's mass is 318 times Earth's, a staggering 1898 trillion trillion kg. That's 1898 followed by 24 zeros!

How long does Jupiter take to go around the Sun?

Jupiter orbits 778.6 million km from the Sun (5.27 AU where 1 AU is Earth's orbital distance).

The planet takes 11.9 years to go through one orbit.

However, as it takes just 9.9 hours to spin on its axis, meaning a Jupiter year has 10,476 Jovian days.

How many moons does Jupiter have?

One of the most staggering facts about Jupiter is that it has 95 known moons officially recognised by the International Astronomical Union (as of October 2023).

The first four moons are called the Galilean moons, as they were discovered in 1610 by Galileo, shortly after he developed his first astronomical telescope - Io, Europa, Ganymede and Callisto.

You can find out more facts about Jupiter's moons in our guide to the Galilean moons.

Most of Jupiter's moons, however, are only a few kilometres across making them very difficult to spot.

There have been hints there could be other moons in distant orbit from the planet, meaning the number could still go up.

Why is it called Jupiter?

The planet is named after the king of the gods, Jupiter (Zeus in Greek) because of its impressive brightness.

Jupiter’s moons have had many different names and designations over the years but are now officially named after characters from Greek and Roman myths, most of whom were one of Jupiter’s many lovers.

How to observe Jupiter

Jupiter is best observed during opposition, when it makes its closest approach to Earth.

During this time the planet is clearly visible to the naked eye as the fourth brightest object in the sky after the Sun, Moon and Venus.

Through binoculars or a small telescope you should be able to make out the Galilean moons – Jupiter’s four largest and closest moons – as well as features such as the Great Red Spot.

With high magnification you should see the planet’s bands come into view, provided Earth's atmosphere isn’t too turbulent.

What missions have explored Jupiter?

While many of the facts we know about Jupiter have come from ground observations, we have also learned a huge amount from the 9 spacecraft that have visited Jupiter, with another on route.

The problem with observing Jupiter for any longer than a few hours is radiation.

The planet has an enormous and incredibly strong magnetic field that traps charged particles, creating belts of intense radiation that can cook spacecrafts' electronics.

The two orbiters that have spent time at Jupiter, the Galileo spacecraft and the Juno spacecraft, were built to resist the worst effects of radiation.

NASA's Juno mission is still in orbit at Jupiter, peering beneath the planet’s cloud layer using a combination of gravitational and magnetic measurements, as well as observing at wavelengths that the top layers of the atmosphere are transparent to, allowing the spacecraft to look below the cloud deck.

In April 2023, ESA's Jupiter Icy moons Explorer (JUICE) launched towards the Jovian system, and is due to arrive in 2031.

Jupiter missions

• Pioneer 10 (1973, NASA)
• Pioneer 11 (1974, NASA)
• Voyager 1 (1979, NASA)
• Voyager 2 (1979, NASA)
• Ulysses (1992 and 2004, NASA)
• Cassini (200, NASA)
• New Horizons (2007, NASA)
• Galileo (1995, NASA)
• Juno (2016, NASA)
• JUICE (in transit, ESA)

Images of Jupiter

If all these Jupiter facts has left you wanting to see more of Jupiter, then look below, where we have a selection of pictures of Jupiter captured by astrophotographers and BBC Sky at Night Magazine readers.

For advice on photographing Jupiter yourself, read our guide on how to photograph planets or our beginner's guide to astrophotography.

And if you've managed to photograph the Gas Giant, don't forget to send us your images or share them with us via Facebook, Twitter and Instagram.

We hope you enjoyed all these facts about Jupiter. Click here to read even more facts about its fellow gas giant Saturn.