Atmosphere of Uranus: composition. What kind of atmosphere does Uranus have?

The images received from the Voyager 2 satellite in the far 90s showed amazing results. The mysterious greenish atmosphere of Uranus is everything that this planet consists of, except for a tiny stone-metal core. The fact is that our ancestors, who own the discoveries of the outer planets of the solar system, were sure that all of them, like the Earth, have a surface, an air envelope and underground layers. As it turned out, gas giants are deprived of all this, as they are representatives of a two-layer model of planets.

History of discovery and general data on the planet

At a distance from the Sun, Uranus is the seventh planet. It was discovered by William Herschel at the end of the 18th century, for the first time using a telescope for astronomical observations. Before that, scientists had long believed that Uranus was only a remote, very bright star. Herschel himself, making notes about this celestial body, initially compared it to a comet, later came to the conclusion that this is possibly another planet of the SS. Of course, after confirming all observations, the discovery was a sensation. However, at that time no one yet knew what kind of atmosphere Uranus really had and what kind of structure it had. Now we know that its orbit is one of the largest in the system. Around the Sun, the planet turns around for 84 Earth years. At the same time, its period of revolution around its axis is just over 17 hours. Because of this, the atmosphere of Uranus, which already consists of heavy gases, becomes incredibly dense and exerts tremendous pressure on the core.

History of atmosphere formation

It is believed that the appearance and physical data of Uranus is influenced by its core, as well as the process of its formation. In comparison with the parameters of the planet itself (25,559 km - equatorial radius), the nucleus is simply miniature. Consequently, it is not a source of energy or a magnetic field, as in the case of Jupiter, and it also does not sufficiently heat all the gases that make up the atmosphere of Uranus. Its composition, in turn, can not be compared with the composition of Jupiter or Saturn, although all these planets fall into one category. The fact is that Uranium is surrounded by ice gases, ice in its highest modifications, clouds of methane and other heavy elements. Light gases such as hydrogen and helium are present in the atmosphere only in a small amount. There are two versions of this paradox. In accordance with the first, the size and gravitational forces of the nucleus at the time of formation of the SS were too small to attract light gases. The second is that in the place where Uranus was formed, there were only heavy chemical components, which became the basis of the planet.

The presence of the atmosphere, its composition

Uranus was first studied in detail only after the Voyager 2 journey, which took pictures with a higher resolution. They allowed scientists to establish the exact structure of the planet itself, as well as its atmosphere. So to say, the air cover of Uranus is divided into three parts:

• The troposphere lies deeper than all. The pressure here is in the range from 100 to 0.1 bar, and the height of this layer does not exceed 500 km from the conditional level of the mantle.
• The stratosphere is the layer of the atmosphere that finds in the middle. It occupies altitudes from 50 to 4000 km.
• Exosphere. The external atmosphere of Uranus, where the pressure tends to zero, and the air temperature is as low as possible.

In all these layers, the following gases are contained in various proportions: helium, hydrogen, methane, ammonia. Also there is water in the form of various modifications of ice and steam. However, the atmosphere of Uranus, whose composition is comparable with the air envelope of Jupiter, is characterized by an incredible coldness. If the air masses are heated to the maximum in the largest gas giant, then they are cooled to 50 Kelvin, and therefore have a large mass.

Troposphere

The deepest layer of the atmosphere is now calculated only theoretically, since the technics of earthlings can not yet reach it. The stone core of the planet is surrounded by clouds consisting of ice crystals. They are heavy and exert tremendous pressure on the center of the planet. They are followed by clouds of ammonium hydrosulfide, then - air formations from hydrogen sulphide and ammonia. The most extreme part of the troposphere is occupied by methane clouds, which tint the planet in the same green color. The air temperature in the troposphere is considered to be the highest on the planet. It fluctuates within 200 K. Because of this, some researchers believe that the planet's mantle forms a large ice layer. But this is only a hypothesis.

Stratosphere

The presence of the Uranus atmosphere provides connections of heavy and light gases, and their synthesis colors the planet in a greenish tinge. All these processes occur in the middle air layer, where molecules of ammonia and methane meet with helium and hydrogen. Crystals of ice here take very different modifications than in the troposphere, they, thanks to ammonia, absorb any light coming from space. The wind speed in the stratosphere reaches 100 m / s, due to which all clouds quickly change their position in space. In the stratosphere, aurorae occur , and fogs are often formed. But there is no such precipitation as snow or rain.

Exosphere

Initially, what kind of atmosphere Uranus, judged by its outer shell. It is a thin strip of crystallized water, which is enveloped by strong currents of winds and is the focus of the lowest temperature in the solar system. It consists of light gases (molecular hydrogen and helium), methane, which is in large quantities in denser layers, is absent here. The speed of the wind in the exosphere reaches 200 m / s, the air temperature drops to 49 K. Therefore, the planet Uranus, whose atmosphere is so icy, became the coldest in our system, even compared to its more distant neighbor Neptune.

The mystery of the magnetic field of Uranus

Everyone knows that the greenish Uranus spins around its axis, lying on its side. Scientists believe that at the time of formation of the SS, the planet collided with an asteroid or other cosmic body, which changed its position, distorting the magnetic field. From the axis, which determines the north and south of the planet relative to the equator, the magnetic axis is shifted by 59 degrees. This creates, first, uneven distribution of gravity, and secondly - unequal tension in the northern and southern hemispheres. Nevertheless, most likely, it is this mysterious position that ensures the presence of the atmosphere of Uranus and its unique composition. Around the core only heavy gases are retained, in the middle layers - crystallized water. Perhaps if the air temperature were higher here, Uranus would become a huge ocean, consisting of ordinary water, which is the source of life.

Uranium absorbs everything and everything around

As we said above, the atmosphere of Uranus is filled with a huge amount of methane. This gas is quite heavy, because it is able to absorb infrared rays. That is, all the light that emanates from the Sun, from other stars and planets, touching the atmosphere of Uranus, turns into a greenish shade. Recently, scientists have noticed that the planet also swallows extraneous gases that are in outer space, which is paradoxical with its weak magnetic field. In the middle layers of the atmosphere, carbon dioxide and carbon monoxide were detected . It is believed that they were drawn to the planet from comets passing by.

The ice kingdoms of our system

The two most extreme planets of the SS are Uranus and Neptune. Both are characterized by bluish shades, both are formed from gases. The atmosphere of Uranus and Neptune is practically the same, except for proportions. The force of gravity and the mass of the nuclei of both planets are practically the same. The lower layers of the Neptune atmosphere , like Uranus, are formed from crystallized water mixed with methane and hydrogen sulphide. Here, near the core, the ice giants are heated to 200 or more Kelvin, thereby forming their own magnetic field. The atmosphere of Uranus and Neptune has the same amount of molecular hydrogen in its composition - more than 80 percent. The outer air layer of Neptune is also characterized by strong winds, but the air temperature here is slightly higher - 60 K.

Conclusion

The presence of the atmosphere of Uranus in principle ensures the existence of this planet. The air envelope is the main constituent part of Uranus. It is strongly heated near the core, but at the same time it cools down as much as possible in the extreme layers. So far, the planet is lifeless because of the lack of oxygen, as well as water in liquid form. But according to the researchers' forecasts, if the temperature of the nucleus begins to rise, the ice crystals will turn into a huge ocean in which new forms of life can arise.