Images taken from the Voyager 2 satellite back in the distant 90s showed us amazing results. The mysterious greenish atmosphere of Uranus is all that this planet is made of, with the exception of 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 shell and underground layers. As it turned out, the gas giants are deprived of all this, as they are representatives of the two-layer model of the planets.
History of discovery and general data about the planet
Uranus is the seventh planet in terms of distance from the Sun. It was discovered by William Herschel at the end of the 18th century, when he was the first to use a telescope for astronomical observations. Before that, for a long time, scientists believed that Uranus was only a distant, very bright star. Herschel himself, making notes about this celestial body, initially compared it with a comet, later came to the conclusion that this may be another SS planet. Of course, after confirming all the observations, the discovery became a sensation. However, at that time, no one knew what kind of atmosphere Uranus actually had.and what is its structure. We now know that its orbit is one of the largest in the system. The planet revolves around the Sun in 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 the formation of the atmosphere
It is believed that the appearance and physical data of Uranus is influenced by its core, as well as the process of its formation. Compared to the parameters of the planet itself (25,559 km - the equatorial radius), the core is simply miniature. Therefore, it does not provide energy or a magnetic field, as in the case of Jupiter, and also does not sufficiently heat all the gases that make up the atmosphere of Uranus. Its composition, in turn, cannot be compared with the composition of Jupiter or Saturn, although all these planets are included in the same category. The fact is that Uranus is surrounded by icy 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 small quantities. There are two versions of this paradox. In accordance with the first, the size and gravitational forces of the core at the time of the 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 high-resolution images. They allowed scientists to establish the exact structure of the planet itself, as well as its atmosphere. So to speak, the air shell of Uranus is divided into three parts:
- The troposphere lies deepest. 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.
- Stratosphere - the layer of the atmosphere in the middle. Occupies heights from 50 to 4000 km.
- Exosphere. The outer atmosphere of Uranus, where pressure tends to zero and the air temperature is at its lowest.
All these layers contain the following gases in various proportions: helium, hydrogen, methane, ammonia. There is also water in the form of various modifications of ice and steam. However, the atmosphere of Uranus, whose composition is comparable to the air shell of Jupiter, is incredibly cold. If in the largest gas giant the air masses are heated to the maximum, then here they are cooled to 50 kelvins, and therefore have a large mass.
Troposphere
The deepest layer of the atmosphere is currently calculated only theoretically, since the technology of earthlings does not yet allow to reach it. The stone core of the planet is surrounded by clouds consisting of ice crystals. They are heavy and put tremendous pressure on the center of the planet. They are followed by clouds of ammonium hydrosulfide, then - air formations of hydrogen sulfide and ammonia. The most extreme part of the troposphere is occupied by methane clouds, whichtint the planet in the same green color. The air temperature in the troposphere is considered the highest on the planet. It fluctuates within 200 K. Because of this, some researchers believe that a large ice layer forms the planet's mantle. But this is just a hypothesis.
Stratosphere
The presence of the atmosphere of Uranus is provided by compounds of heavy and light gases, and their synthesis paints the planet in a greenish hue. All these processes take place in the middle air layer, where molecules of ammonia and methane meet with helium and hydrogen. Ice crystals here take on completely different modifications than in the troposphere; thanks to ammonia, they absorb any light coming from space. The speed of winds in the stratosphere reaches 100 m / s, due to which all clouds quickly change their position in space. Auroras occur in the stratosphere, fogs often form. But there is no precipitation such as snow or rain.
Exosphere
Initially, the atmosphere of Uranus was judged precisely by its outer shell. It is a thin strip of crystallized water that is shrouded in strong wind currents and is the focus of the lowest temperature in the solar system. It consists of light gases (molecular hydrogen and helium), while methane, which is found in large quantities in denser layers, is absent here. The wind speed in the exosphere reaches 200 m / s, the air temperature drops to 49 K. That is why the planet Uranus, whose atmosphere is soicy, has become the coldest in our system, even compared to its more distant neighbor, Neptune.
The mystery of Uranus' magnetic field
Everyone knows very well that the greenish Uranus spins around its axis, lying on its side. Scientists believe that at the time of the 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 that determines the north and south of the planet relative to the equator, the magnetic axis is offset by 59 degrees. This creates, firstly, an uneven distribution of gravity, and secondly, an unequal tension in the northern and southern hemispheres. Nevertheless, most likely, it is this mysterious position that provides 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 here were higher, Uranus would become a huge ocean, consisting of ordinary water, which is the source of life.
Uranus 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 comes from the Sun, from other stars and planets, touching the atmosphere of Uranus, turns into a greenish tint. Recently, scientists have noticed that the planet also swallows foreign gases that are in outer space, which is paradoxical with its weakmagnetic field. Carbon dioxide and carbon monoxide were found in the composition of the middle layers of the atmosphere. It is believed that they were attracted to the planet from passing comets.
The ice realms of our system
The two outermost planets of the SS are Uranus and Neptune. Both are characterized by bluish hues, both are formed from gases. The atmosphere of Uranus and Neptune is practically the same, except for the proportions. The force of gravity and the mass of the cores of both planets is almost the same. The lower layers of the atmosphere of Neptune, like Uranus, are formed from crystallized water mixed with methane and hydrogen sulfide. Here, near the core, the ice giants heat up to 200 or more Kelvin, thereby forming their 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 shell is the main constituent part of Uranus. It heats up strongly near the core, but at the same time it cools down as much as possible in the outermost layers. So far, the planet is lifeless due to the lack of oxygen, as well as liquid water. But if the temperature of the core begins to rise, the researchers predict, the ice crystals will turn into a huge ocean in which new forms of life can emerge.
