Uranus, the seventh planet from the Sun, is twenty times further out from the Sun than the Earth. This giant planet is covered with a thick atmosphere of hydrogen and helium, but is far smaller than a gas giant like Jupiter. Uranus is fourteen times the mass of the Earth, and about four times the size. Most of the planet, beneath the thick gas is a mix of mainly water and ammonia, in a great slushy ocean and this earns Uranus the name of an ice giant. There are clouds of water and methane in its atmosphere. If you were to dive down into Uranus then at first it would be cold, about -370 F – the coldest place in a planet in our Solar System – but as you descended it would get hotter and hotter as the weight of the planet squashes things down. At the center of Uranus, there is probably a rocky core, and the temperature may reach as high as 8,500 F!
The most amazing thing about Uranus is that it spins almost on its side! Most planets spin so that their north and south poles are pointing away from the direction they orbit around the Sun, but Uranus is tilted a little more than all the way over (by 98 degrees) – so its north and south poles actually point the opposite way from most planets. It takes Uranus 84 years to orbit around the Sun, and for half of that time the north pole points towards the Sun, and then for the other half of the time the south pole points towards the Sun.
Think about it
What could have made Uranus tilt over on its side? When the planets were forming, four billion years ago, another big planet might have collided with Uranus and pushed it over onto its side. There’s no easy way a planet can right itself and so Uranus has stayed that way ever since.
Rings and moons
Like the other giant planets, Uranus has a lot of moons, 27 in total. Most of them are quite small. The biggest is called Titania and is only half the size of the Earth’s Moon. Uranus also has some rings, but most of the material they are made from is dark and hard to see, although the rings are probably quite young, no more than 600 million years old!
Image of Uranus and its rings, a strange cloud is also visible
The only spacecraft to ever visit Uranus was the robotic explorer Voyager 2. In 1986 it sped past Uranus and took many images and collected a bunch of data. NASA is planning another mission to visit the ice giants. So if you’re lucky, we’ll soon be able to get stunning close up images of this amazing planet from deep in our solar system. When we look at these bright blue images, it might be hard to imagine that these places are real. But remember that these are some of our closest neighbors in space, and you can even see them yourself if you have a good telescope and know where to look!
Illustration of Uranus, its moons, and its rings. Two new rings and a moon were discovered using the Hubble Space Telescope – in orbit around the Earth.