Uranus, the third largest planet in the Solar System, is named after the ancient Greek god of the heavens.
With its uniform bluish-green appearance, the planet looks quite boring at first glance;
however, it is probably the most unusual planet traveling around the Sun.
Although it belongs to the family of giant planets, it is only four times larger than Earth.
Yet, since it is 19 times farther from the Sun than the Earth, it takes almost 84 years for Uranus to orbit around it.
Like the rest of the gaseous planets, Uranus turns around its axis fairly quickly.
The day is only 17 hours long.
Although Uranus belongs to the family of gaseous planets
it contains less hydrogen
than other gaseous planets and a much higher percentage of rocks and ice.
Hydrogen constitutes 83% of the atmosphere
There also about 15% helium
and 2% methane
Methane has the ability to absorb red light from the Sun, making the planet appear blue.
Even though Voyager 2
spacecraft did not see any bright features in the atmosphere, this does not mean that they do not exist.
They might appear for a limited time when the seasons change,
which would be a challenge as the seasons seldom change with such a long year on Uranus totaling 84 Earth years.
Under the thick layer of clouds, Uranus has a surface of ice and rocks.
The planet does not have a layer of liquid hydrogen like Jupiter and Saturn,
but it has larger rock core. At such a great distance from the sun, Uranus is a bitterly cold planet.
The temperature is about -195°K
, which is actually higher than expected.
This means that Uranus also has his own internal source of energy due to gravitational contraction
Uranus has an unusual magnetic field
which is moved out of center and inclined by 60 degrees off its axis.
Because of the great distance it is difficult to study Uranus with a telescope.
Even with big telescope it looks like pale bluish-green circle.
The only spacecraft that visited the planet was the Voyager 2
It main contributions included photographing the planet and discovering five new rings and four moons.
Like the other gaseous planets, Uranus has rings and moons. Uranus's rings are dark like Jupiter's.
Uranus has 27 moons of which the five largest are: Miranda, Ariel, Umbriel, Titania and Oberon. All of them are named after Shakespearean heroes.
While the biggest satellites formed together with the planet, the smallest ones are probably captured objects from Kuiper belt
The orientation of Uranus on its axis is quite unusual. While the other planets have axises almost perpendicular or slightly tilted to their orbital plane,
Uranus's axis almost lies directly in this plane. It looks like something "kicked" the planet aside.
As a result the seasons are quite strange. During the summer in the south hemisphere the south pole looks towards the sun and is the "hottest" place in the planet.
The summer lasts about 42 years and the sun never sets on the pole (similar to "white nights" around the Earth's poles).
When the seasons change the equator is the hottest place. The cloud activity seems to increase during this time.
Thereafter the summer for the north hemisphere begins another 42 year cycle.