Things about Uranus

 What we know about the rolling planet 

Introduction:

Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the solar system. At its brightest, Uranus is visible to the unaided eye as a blue-green point of light. Both, Uranus and Neptune have similar chemical compositions which differ from the larger gas giants like Jupiter and Saturn. This is why scientists often classify Uranus and Neptune as 'ice giants' to distinguish them from other giant planets.

Uranus orbits the Sun once every 84 years, taking an average of 7 years to pass through each of the dozen constellations of the zodiac. In 2033, the planet will have made its third complete orbit around the Sun since being discovered in 1781. Uranus takes 17.24 hours to complete one rotation. Its mean distance from the Sun is nearly 2.9 billion kilometers, which is more than 19 times as far as the Earth. Uranus is relatively of a low density (about 1.3 times that of water).

The Uranian system has a unique configuration because its axis of rotation is tilted sideways, almost as if it rolls like a ball. Therefore, its north and south poles lie where most other planets have their equators. Plus, the planet is tidally locked; this means that each pole faces the sun for 42 years. When the Voyager 2 traveled to Uranus in 1986, the planet was seen as 'featureless' in visible light, without the cloud bands or storms. 

Atmosphere and Internal structure:

Uranus' atmosphere is similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, but it contains more 'ices' such as water, ammonia, and methane, along with traces of other hydrocarbons. The planet's atmosphere comprises of 82.5% hydrogen, 15.2% helium, and 2.3% methane. Uranus has the coldest planetary atmosphere in the solar system; its minimum temperature drops to 49 K (-224℃). It has a complex, layered cloud structure with water thought to make up the lowest clouds and methane as the uppermost layer of clouds. Methane in the Uranian atmosphere absorbs the red wavelengths of sunlight, giving the planet its blue-green color. 

The carbon-to-hydrogen ratio of Uranus is 24 times that of the Sun. Methane in the Uranian atmosphere absorbs the red wavelengths of sunlight, giving the planet its blue-green color. One unusual phenomenon on Uranus includes diamond rain, which is thought to sink thousands of miles below the surface of the icy giant planets such as Uranus and Neptune. Carbon and hydrogen and thought to compress under extreme heat and pressure deep in the atmosphere of these planets to form diamonds, which are then thought to sink downward, eventually settling around the cores of those worlds.

The relatively fast rotation of Uranus causes violent winds in the atmosphere. Because of the extreme axial tilt of Uranus, sunlight reaches some areas for the first time in years, it heats up the atmosphere triggering gigantic springtime storms. This leads to the formation of cloud markings on the visible surface to rotate around the planet with periods ranging from 18 hours near the equator to 14 hours at higher latitudes. In 2014, astronomers got their first glimpse at summer storms raging on Uranus. Similarly, these massive storms took place seven years after the planet reached its closest approach to the Sun, and it remains a mystery why the giant storms occurred after the sun's heating on the planet was at a maximum. 

Uranus has no solid surface because of its fluid interior structure. The standard model structure of Uranus consists of three layers: a rocky silicate/iron-nickel core in the center, an icy mantle in the middle, and an outer gaseous hydrogen/helium envelope. The core's mass is estimated to be about 0.55% of Earth's masses with a radius less than 20% of the whole of Uranus. Its internal structure is made up of a mantle of water, ammonia, and methane ices, as well as a core of iron and magnesium silicate. 

Moons and Rings:

Uranus has 27 known moons, five of which are relatively large; and a system of narrow rings. The rings of Uranus were first to be seen after Saturn's. Scientists have identified a set of two rings around the planet. The inner system of rings consists mostly of narrow, dark rings, while the outer system of two more distant rings are brightly colored: one red and the other blue. Anomalies in Uranus' rings lead scientists to suspect there might still be more moons.

Oberon, Titania, Miranda, Ariel, and Umbriel are the largest Uranian moons, first discovered by Herschel in 1787. Each one is comprised of roughly equal amounts of rock and ice, except for Miranda which is made primarily of ice, that may include ammonia and carbon dioxide. In the case of Titania and Oberon, it is believed that liquid water oceans may exist at the core/mantle boundary. 

After that in 1986, ten additional moons were discovered: Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Portia, Rosalind, Cressida, and Belinda. Each of these moons are roughly half water and half rock. Since the astronomers are using the Hubble telescope and ground-based observatories have raised a total of 27 known moons, and spotting these was tricky- they were as little as 8 to 10 miles (12 to 16 km) across, blacker than asphalt and nearly 3 billion miles (4.8 billion km) away. The space between Cordelia, Ophelia, and Miranda is a swarm of eight small satellites crowded together so tightly that astronomers don't yet understand how the little moons have managed to avoid crashing into each other. These moons are composed of ices contaminated with a dark material, which are most likely organic compounds darkened by exposure to UV radiation.

In addition to moons, Uranus may have a collection of Trojan asteroids - objects that share the same orbit as the planet - in a special region known as a Lagrange point. The first was discovered in 2013, despite the claims that were made that the planet's Lagrange point would be too unstable to host such bodies.