The 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 consists of, with the exception of a tiny stone-metal core. The fact is that our ancestors, who owned the discoveries of the outer planets of the solar system, were convinced that all of them, like the Earth, had a surface, an air shell and underground layers. As it turned out, gas giants are deprived of all this, since they are representatives of a two-layer model of planets.
Discovery History and General Data on the Planet
Uranus is the seventh planet remotely from the Sun. It was discovered by William Herschel at the end of the 18th century, using the telescope for the first time for astronomical observations. Prior to this, for a long time, scientists believed that Uranus is 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 is possibly another SS planet. Of course, after confirming all the observations, the discovery became a sensation. However, at that time no one knew what atmosphere Uranus actually had and what its structure was. We now know that its orbit is one of the largest in the system. Around the Sun, the planet turns around 84 Earth years. Moreover, its circulation period on its axis is a little more than 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
It is believed that the appearance and physical data of Uranus are affected precisely by its core, as well as the process of its formation. Compared to the parameters of the planet itself (25,559 km - equatorial radius), the core is simply miniature. Consequently, it is not a source of energy or magnetic field, as is the case with 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 fall into 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. According to the first, the size and gravitational forces of the nucleus 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 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 say, the air shell of Uranus is divided into three parts:
- The troposphere lies most deeply. 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 a layer of the atmosphere located in the middle. It occupies heights 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. There is also water in the form of various modifications of ice and steam. However, the atmosphere of Uranus, the composition of which 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 kelvin, therefore they have a large mass.
Troposphere
The deepest layer of the atmosphere is now calculated only theoretically, as far as the technique of earthlings does not allow it to reach it yet. The stone core of the planet is surrounded by clouds consisting of ice crystals. They are heavy and put enormous pressure on the center of the planet. They are followed by clouds of ammonium hydrosulfide, then - air formations from hydrogen sulfide and ammonia. The most extreme part of the troposphere is occupied by methane clouds, which tint the planet in that 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 mantle of the planet. But this is only a hypothesis.
Stratosphere
The presence of the atmosphere of Uranus is ensured by compounds of heavy and light gases, and their synthesis colors the planet in a greenish tint. All these processes occur in the middle air layer, where ammonia and methane molecules with helium and hydrogen are found. Ice crystals here take completely different modifications than in the troposphere; thanks to ammonia, they absorb any light coming from space. The wind speed in the stratosphere reaches 100 m / s, so that all clouds quickly change their position in space. Auroras occur in the stratosphere , fogs often form. But precipitation such as snow or rain is not observed.
Exosphere
Initially, the atmosphere of Uranus was judged precisely by its outer shell. This is a thin strip of crystallized water, which is wrapped in 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), but methane, which in large quantities is in denser layers, is absent here. The wind speed in the exosphere reaches 200 m / s, the air temperature drops to 49 K. Therefore, the planet Uranus, whose atmosphere is so icy, has become the coldest in our system, even compared to its farthest neighbor - Neptune.
The mystery of the magnetic field of Uranus
Everyone knows that the greenish Uranus spins on 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 defines 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, 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 here were higher, Uranus would become a huge ocean, consisting of ordinary water, which is the source of life.
Uranus swallows 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 capable of absorbing 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 extraneous gases that are in outer space, which is paradoxical with its weak magnetic field. Carbon dioxide and carbon monoxide were detected in the middle atmosphere . It is believed that they were drawn to the planet from flying comets.
The ice kingdoms of our system
The two most extreme SS planets are Uranus and Neptune. Both are characterized by bluish hues, both are formed from gases. The atmosphere of Uranus and Neptune is almost the same, with the exception of proportions. The force of gravity and the mass of the nuclei of both planets are almost the same. The lower atmosphere of Neptune, like Uranus, is 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 is very hot near the core, but at the same time cools down in the extreme layers. So far, the planet is lifeless due to the lack of oxygen, as well as water in liquid form. But according to researchers, if the core temperature starts to rise, ice crystals will turn into a huge ocean in which new life forms can be born.