A cold and windy planet, Uranus is the seventh planet from the Sun in our Solar System.
Below we cover what Uranus is like, how far is it from Earth, if it could be habitable by humans, and loads other Uranus facts.
The discovery of Uranus and how it got its name
Sir William Herschel discovered Uranus in 1781. The dimness of the planet may have prevented the planted from being discovered earlier. Initially, Herschel believed Uranus was a comet. But after a couple of years, Uranus was confirmed to be a planet, partly due to the observations made by Johann Elert Bode, another astronomer.
Herschel wanted to name the planet Georgian Sidus, in remembrance of King George III. However, Johann Bode suggested the planet be named Uranus instead, after Ouranos, the Greek deity. Most other planets have been named after ancient Roman gods. Uranus is the only planet with a Greek deity’s name behind it.
Uranium, the radioactive element, got its name from Uranus, after its discovery in 1789, eight years post Uranus was found.
Where is Uranus?
Uranus is the seventh planet from the Sun.
Since our solar system is constantly moving, the distance between Uranus and Earth changes every day. The closest both get to each other is at a gap of 2.6 billion kilometers. The farthest distance between the two is 3.2 billion kilometers.
As far as the distance between the Sun and Uranus is concerned, the gap constantly keeps changing between the two too. Since Uranus moves elliptically around the Sun, it is 2.5 billion kilometers away at its closest point. The farthest could be 3 billion kilometers.
This massive distance from the Sun is the reason why Uranus gets so little warmth and light.
What is it like on Uranus?
Uranus is predominantly water and ice. It is the coldest of all planets, with the atmospheric temperature capable of falling as low as -224 degrees Celsius – despite not being the farthest from the Sun.
The planet is extremely windy and cold and it has an icy atmosphere, which is dramatically different from other big planets.
Uranus’ atmosphere is primarily gas comprising atomic helium and molecular hydrogen, with little amounts of methane. The atmosphere’s helium and hydrogen composition has more methane than Saturn or Jupiter.
Methane gas takes in light on the spectrum’s red end, giving the planet its blue-green color. If you flew down via the atmosphere’s layers, the clouds in your surrounding would become denser, colder and bluer since the gases would have absorbed a lot of the spectrum visible.
Deep underneath, you would find Uranus’ unruly magnetic field, which is slanted 60 degrees, a lot stronger on one of the poles, and moved some thousand kilometers off-center. Some astronomers think the planet’s warped field could be the outcome of the vast ionic liquid oceans hidden under the greenish clouds.
The deeper layers of clouds could go as low as 360 degrees under zero, which is colder compared to any other solar system planet. Yet, the exterior layer could hit temperature levels in excess of 500 degrees Celsius, a lot higher than other gas giants.
Uranus rotates once on its axis approximately every 17 hours and does so in the opposite direction of Earth. Like Venus, it turns east to west.
Since the planet is located much farther from the Sun, it takes 84 Earth years for the planet to orbit the Sun completely. Uranus is not alone during this journey, it is accompanied by its 13 known rings and 27 known moons.
Due to its unique sideways rotation, the planet has some unusual seasons. The north pole of the planet gets no sunlight for 21 years during winter and sunlight for 21 years during summer. It then gets 42 years of night and day time during fall and spring, wherein the cycling between day and night happens every 17 hours.
In 2007, the planet reached its equinox, which indicates the period when the equator is directly facing the Sun and equal amounts of sunlight hitting the hemispheres.
What is Uranus made of?
Uranus’ density is 1.27 grams every cubic centimetre, which makes it the least dense planet after Saturn. The low density denotes the planet is predominantly ice instead of gas.
Uranus’ upper layer is hydrogen, with helium mixed in it. Below that layer is an icy mantle surrounding an ice core and rock.
The atmosphere atop is composed of ammonia, water, and methane ice crystals, which provide Uranus its pale blue hue.
How big is Uranus?
Uranus is the third biggest planet after Jupiter and Saturn. It is the biggest of the icy planets.
The mean radius is 25,362 kilometers, which makes its diameter four times Earth’s diameter.
Like several other solar system bodies, Uranus’ rapid speed induces a marginal bulge near its center.
At its poles, Uranus’ radius is 24,973 kilometers. But near the equator, the planet expands to 25,559 kilometers. Due to this bulge, Uranus’ shape is an oblate spheroid.
Is there life on Uranus?
Uranus has no support for life. The extreme temperatures and the sun not showing up for years at a time account for this.
The biggest practical reason why Uranus isn’t ideal for human occupation though is the lack of a solid surface. The planet is primarily made of ice with an atmosphere of helium and hydrogen.
How many moons does Uranus have?
Uranus has 27 moons.
Its moons are named after Alexander Pope and William Shakespeare-created characters, including Titania, Miranda, Umbriel, and Oberon.
All the moons are frozen with dark exteriors. Some of them are rock and ice mixtures.
Umbriel is strangely dark but has a mysteriously bright band. Oberon is crater-covered and has one huge mountain. Miranda is the most interesting of all the moons – it has terraces, ice canyons, and other unique-looking surface areas. It’s scarred by fissures and cracks.
Uranus’ moons motions can be termed as ‘unstable’ and ‘random’. The moons constantly push and pull each other gravitationally, creating a lot of unpredictability surrounding their long-term orbits. In the future, some of these moons are likely to crash into each other.
Does Uranus have rings?
Though not as renowned as Saturn’s rings, Uranus has some extremely thin rings of its own – two outer rings and eleven inner rings. They were probably created when one or several of Uranus’ moons broke up during impact.
The inner rings were found during 1977. The two external rings were discovered during 2003-2005, thanks to the images sent by Hubble Space Telescope.
The outermost ring is bright blue in color. The rings encircle the planet’s equator. However, when observed from Earth, the rings look like they are standing almost straight. This is due to Uranus being tipped almost totally on its side in relation to the solar system’s plane.
Scientists believe a collision immediately post the formation of Uranus resulted in this intriguing misalignment.
What missions have humans sent to explore around Uranus?
Voyager 2, in 1986, is the only spacecraft to have come anywhere close to the planet, being 81,500 kilometers away from the planet.
It was launched during August 1977. The spacecraft returned Uranus’ close-up shots, and also images of its rings and moons. It is believed the spacecraft is still in function, flying in deep space and positioned 16 billion kilometers or more from Earth.
Other than Voyager 2, no other spacecraft has been sent to study the planet up-close and at length. When Voyager 2 made a visit, Uranus’ south pole was directly confronting the Sun (almost), with the north pole turned away.
Uranus still has a lot of mystery surrounding it, and one of the reasons for this could be the lack of attention or coverage it has received from Earth. Uranus is located extremely far from Earth – 2.5 billion to 3.2 billion kilometers away.
Uranus is also not easy to predict. Though the upper atmosphere’s fluctuating temperatures and chaotic movement of the moons isn’t too fast to hinder or intimidate a spacecraft, there are definitely reasons to be wary of undiscovered debris and moons orbiting the planet.
NASA considered sending the Cassini-Huygens mission to Uranus after it was done studying Saturn but it would have taken a decade for the mission to travel from Saturn to Uranus. Not to mention, Cassini had already taken seven years to reach Saturn from Earth.
The plan was later withdrawn and Cassini made a suicidal dive into Saturn deliberately in 2017.
Uranus planet information
- Distance from Earth: 2.735 billion kilometers
- Distance from Sun: 2.871 billion kilometers
- Temperature: -216 degrees Celsius to 577 degrees Celsius (outer layer)
- Mass: 8.68 × 10^25 kg (equivalent to 15 Earths)
- Surface area: 8.083 billion km²
- Volume: 6.83×1013 cubic kilometers
- Diameter: 51,118 kilometres
- Radius: 25,362 kilometres
- Orbital period: 84 years