Jupiter is the largest planet in our solar system and is truly a giant. It is large enough for 11 Earths to fit across its face and 1,300 to fit inside it. There are four giant planets in our Solar System. The next biggest is Saturn, followed by Uranus, and Neptune. They are also known as “gas giants” because of their colourful ice-cold gas atmospheres.
You won’t believe it!
Jupiter is shrinking. When it was young it was five times its present size. It is cooling and getting smaller by about 2 (0.8 in) a year.
Tell me more: Jupiter
Clouds: Jupiter’s stripes are clouds in its violent atmosphere. They are pulled into bands parallel to the equator by the planet’s fast spin.
Zones: White bands of cool rising air.
Spots: Giant weather storms.
Belts: Red-brown bands of warmer, falling air.
Great Red Spot: This weather storm is bigger than Earth. It rotates anticlockwise every 6-7 days, and has been raging for more than 300 years.
Four biggest planets
Jupiter
Diameter: 142,984 km (88,846 miles)
Distance from Sun: 778.3 million km (483.6 million miles)
Rotation: 9.9 hours
Orbit of the Sun: 11.9 years
Saturn
Diameter: 120,536 km (74,898 miles)
Distance from Sum: 1.43 billion km (888 million miles)
Rotation: 10.7 hours Orbit of the Sun: 29.5 years
Uranus
Diameter: 51,118 km (31,763 miles)
Distance from Sun: 2.87 billion km (1.78 billion miles)
Rotation: 17.3 hours
Orbit of the Sun: 84.0 years
Neptune
Diameter: 49,532 km (30,760 miles)
Distance from Sun: 4.5 billion km (2.8 billion miles)
Rotation: 16.1 hours Orbit of the Bun: 164.8 years
FAST FACTS: Giant planet structure
Temperature and density increase towards the centre of giant planets. This affects the physical state of the material the planets are made up of.
In Jupiter and Saturn, squashed gases become fluid and more like liquids. Deeper still, the gases are like molten metal.
In the heart of all four giants are round cores of rocky and metallic material.
All four giant planets have rings. They look solid from a distance but are made of individual pieces that follow their own orbits around their planet.
Jupiter is named after the king of the Roman gods and ruler of the heavens.
Weird or what?
Jupiter has a powerful magnetic field – it is as if there is a large bar magnet inside the planet. It’s the strongest field of any planet – about 20,000 times more forceful than Earth’s.
Ringed world
- As Saturn orbits the Sun, its rings can be seen from different angles.
- Th rings are made of particles and chunks of dirty ice in orbit around the planet.
- The pieces range in size from dust grains to large boulders several metres across.
- The pieces are also very reflective. The rings shine brightly and are easy to see.
You won’t believe it!
Saturn is the least dense of all the planets – if you could put it in a bath of water, it would float.
Tell me more: Saturn
- Saturn is named after the father of the Roman god Jupiter.
- The first to see Saturn’s rings was Italian astronomer Galileo Galilei in 1610. He thought they were handle-like ears fixed to the sides of the planet.
- None of the gas giants are perfect spheres. They are all oblate (squashed balls). Saturn’s diameter is almost one-tenth bigger at its equator than at its poles.
Uranus
- Uranus is named after the father of the Roman god Saturn.
- Uranus became the seventh planet in the Solar System, and the first to be discovered by telescope when it was unexpectedly spotted by astronomer William Herschel on 13 March 1781.
- Uranus rolls around its orbit on its side. The planet is tilted over by 98 degrees, possibly as a result of a collision with a large asteroid when it was young.
- Like the other three gas giants, Uranus’s atmosphere is mostly hydrogen. It also contains methane, which absorbs red light and makes the planet blue.
Neptune
- Neptune is named after the Roman god of the sea.
- It’s the fourth largest of the gas giants.
- Neptune is about 30 times further from the Sun than Earth.
- It is the coldest giant -200°C (-320°F) at its cloud tops, and has the faster winds of any planet, reaching speeds up to 2,160 kph (1,340 mph) near its equator.
You won’t believe it!
Neptune was only discovered on 23 September 1846. Although it had been noticed many times before, astronomers thought it was a star.