|Distance from Sun:||1.784 billion mi|
|Polar Diameter:||49,946 km|
|Orbital period:||84 years|
|Mass:||8.68 × 10^25 kg (15 Earths)|
|Effective Temperature:||-216 °C|
|Moons:||(27, including Miranda, Titania, Ariel, Umbriel & Oberon)|
|Date of Discovery:||March 13, 1781 by William Herschel|
Uranus in the third of the gas giants, the third largest planet in our Solar System in relation to diameter, and the fourth most massive in our Solar System.
Named after the father of the Roman god, Saturn, it is also the first planet that was actually discovered in what we call “modern history by William Herschel.
Herschel almost missed finding Uranus, as he was really charting stars when he found a disk-like object that he thought was a comet. By the time he was done calculating the orbit, he realized it was a planet.
Thus far, Voyager 2 is the only spacecraft that has visited Uranus, which happened in 1986.
Although thousands of pictures were taken of Uranus and its rings and moons, they didn’t show much detail other than the greenish-blue color.
The Hubble Telescope has given a lot more insight into the atmosphere of Uranus, including that it has latitudinal bands that are similar to other gas giants.
The winds on Uranus can also reach over 576 km/hr. One of the reasons the atmosphere is so difficult to see is that the cloud layers that are visible are made up of mostly methane, which absorbs red color wavelengths and reflects only those that are green and blue.
Below the outer layer of methane, the atmosphere is around 83% hydrogen, 15% helium and trace amounts of acetylene and methane.
This is similar to other gas giants, but Uranus differs in that its atmosphere is mostly ice, whereas the others are gas. It means that the atmosphere is around -224 degrees C, the coldest in the Solar System, and it is constant.
The inside of Uranus is believed to contain two layers which are the core and a mantle. Scientists think that the core is mostly made up of rock and ice and the mantle is around 13.3 times the mass of the Earth and made up of water, ammonia, and other elements.
The difference between Uranus and other gas giants also relates to the mantle as it may be “icy” but it’s also hot and thick. Unlike other gas giants, Uranus doesn’t emit more energy than it gets from the Sun and scientists are interested in finding out why Uranus generates so little heat.
One of the most unique aspects of Uranus is its odd rotation when compared to all of the other planets. Ever planet (except Uranus) has an axis of rotation that is nearly perpendicular with its orbital plane.
Uranus’ axis has an almost 98 degree tilt, which means that it rotates on its side. The resulting situation is that it’s north pole points only half of the year towards the sun and the south pole points the other half of its year.
Daytime on one of the hemisphere means night on the other for 42 Earth years at a time.
Surprisingly, Uranus does have rings, although they weren’t discovered until 1977. The reason for the late discovery is not only the distance from the Earth, but also their low reflection in light.
Voyager 2 spacecraft did a flyby of some of the rings in its 1986 mission and then later the Hubble Telescope found two additional rings in 2005.
These rings are a bit different than those that we are familiar with around Saturn as they are made up of much larger particles of both ice and dust as opposed to Saturn’s much smaller size and mostly ice.
William Herschel’s discovery of Uranus allowed him to choose the name of “Georgian Sidus” after King George III, however, the scientific community didn’t like it and later accepts the name suggested by astronomer Johann Bode of the Greek god Ouranos.