URANUS
Uranus is the third biggest planet, and is four times bigger across than Earth. It is so far from the Earth that it is barely visible with the naked eye. Because of this it was not discovered until 1700s, with the help of a telescope
Who discovered Uranus?
In March 1781, an English astronomer named William Herschel was looking at the sky through a telescope. He spied what he thought must be a new comet. But it was actually a new planet. Until then, astronomers knew of only six planets. The new planet, which was late called Uranus , turned out to be twice as far away from the Sun as Saturn.
Why is Uranus sometimes called the topsy-turvy planet?
All planets spin as they orbit the Sun. We say they spin round their axis (an imaginary line that goes through their north and south poles). In most planets the axis is nearly upright as the planet spins. But Uranus spins on an axis at right-angle to normal, so it is as if Uranus is lying on its side. This means that, at times in its orbits, Uranus’ poles point straight at the Sun. As a result, they become hotter than the rest of the planet, instead of always being colder, as on Earth.
How many rings does Uranus have?
Astronomers use to think that Saturn was the only planet that had rings circling it. But, in 1977, they discovered that Uranus had rings too. There are about 11 main rings, made up of bits of rock up to a metre across, which whizz round the planet at high speed. The particles in some of the rings are kept in place by tiny ‘shepherd’ moons.
Which probe has visited Uranus?
We can find out very little about Uranus through telescopes because it is so far away. Most of what we know comes from Voyager 2 space probe, which visited Uranus in 1986. Voyager 2 had earlier visited Jupiter(1979) and Saturn(1981). It has now gone far beyond the planets, and will soon leave the Solar System and begin a journey to the stars.
What is Uranus made of?
Uranus has a thick atmosphere of hydrogen, helium and methane ice, and a mantle of water, ammonia and methane ice. At the centre there is an iron silicate core.
What is Uranus’ moons like?
We can only see the five largest of Uranus’ moons from Earth – Miranda, Ariel, Umbriel, Titania and Oberon. Ten smaller moons were discovered by Voyager 2. The large moons are great balls of rock and ice, pitted with craters, and with long cracks in their surface. Titania is the biggest moon. It is about 1,600 kilometres across.
What is special about Miranda?
Miranda is the smallest moon that can be seen from Earth, with a diameter of only about 500 kilometres. Close-up photographs show it to be the most interesting moon of all. Its surface is a patchwork of different kinds of landscape – craters, grooves, cliffs and valleys. Astronomers think that, ages ago, Miranda shattered into pieces when it collided with another body. Then the pieces came together to create the landscape we see today.
URANUS DATA
Diameter at equators : 51,000 km
Average distance from Sun : 2,870 million km
Minimum distance from Earth : 2,600 million km
Turns on axis : 17 hours 14 minutes
Circles Sun : 84 Earth-years
Temperature at cloud tops : -200°C
Satellites : 15
Uranus is the third biggest planet, and is four times bigger across than Earth. It is so far from the Earth that it is barely visible with the naked eye. Because of this it was not discovered until 1700s, with the help of a telescope
Who discovered Uranus?
In March 1781, an English astronomer named William Herschel was looking at the sky through a telescope. He spied what he thought must be a new comet. But it was actually a new planet. Until then, astronomers knew of only six planets. The new planet, which was late called Uranus , turned out to be twice as far away from the Sun as Saturn.
Why is Uranus sometimes called the topsy-turvy planet?
All planets spin as they orbit the Sun. We say they spin round their axis (an imaginary line that goes through their north and south poles). In most planets the axis is nearly upright as the planet spins. But Uranus spins on an axis at right-angle to normal, so it is as if Uranus is lying on its side. This means that, at times in its orbits, Uranus’ poles point straight at the Sun. As a result, they become hotter than the rest of the planet, instead of always being colder, as on Earth.
How many rings does Uranus have?
Astronomers use to think that Saturn was the only planet that had rings circling it. But, in 1977, they discovered that Uranus had rings too. There are about 11 main rings, made up of bits of rock up to a metre across, which whizz round the planet at high speed. The particles in some of the rings are kept in place by tiny ‘shepherd’ moons.
Which probe has visited Uranus?
We can find out very little about Uranus through telescopes because it is so far away. Most of what we know comes from Voyager 2 space probe, which visited Uranus in 1986. Voyager 2 had earlier visited Jupiter(1979) and Saturn(1981). It has now gone far beyond the planets, and will soon leave the Solar System and begin a journey to the stars.
What is Uranus made of?
Uranus has a thick atmosphere of hydrogen, helium and methane ice, and a mantle of water, ammonia and methane ice. At the centre there is an iron silicate core.
What is Uranus’ moons like?
We can only see the five largest of Uranus’ moons from Earth – Miranda, Ariel, Umbriel, Titania and Oberon. Ten smaller moons were discovered by Voyager 2. The large moons are great balls of rock and ice, pitted with craters, and with long cracks in their surface. Titania is the biggest moon. It is about 1,600 kilometres across.
What is special about Miranda?
Miranda is the smallest moon that can be seen from Earth, with a diameter of only about 500 kilometres. Close-up photographs show it to be the most interesting moon of all. Its surface is a patchwork of different kinds of landscape – craters, grooves, cliffs and valleys. Astronomers think that, ages ago, Miranda shattered into pieces when it collided with another body. Then the pieces came together to create the landscape we see today.
URANUS DATA
Diameter at equators : 51,000 km
Average distance from Sun : 2,870 million km
Minimum distance from Earth : 2,600 million km
Turns on axis : 17 hours 14 minutes
Circles Sun : 84 Earth-years
Temperature at cloud tops : -200°C
Satellites : 15
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