Uranus, definition and study. A-Z Index of Cognitio.

Uranus is the seventh planet of the solar system in order away from the Sun.

Sun, definition and study. A-Z index of Cognitio.


Brings the name of the Greek god of heaven Uranus, father of Crono (Saturn), in turn father of Zeus (Jupiter). Although it is also visible to the naked eye, like the other five planets known since antiquity, it was never recognized as such because of its low brightness and its particularly slow orbit; It was only discovered on March 13, 1781 by William Herschel, thus becoming the first planet to be discovered through a telescope. A curiosity about his discovery is that it came quite unexpectedly: the planets visible to the naked eye (up to Saturn) were known for millennia and no one suspected the existence of other planets until the discovery of Herschel that he noticed as a particular star he seemed to move. From that moment on, no one was more sure of the real number of planets in our solar system.

Solar system, definition and study. A-Z Index of Cognitio.

Solar system

The chemical composition of Uranus is similar to that of Neptune and both have a different composition than that of the largest gigantic (Jupiter and Saturn). For this reason astronomers sometimes prefer to refer to these two planets by treating them as a separate class, the “ghostly giants”. The atmosphere of the planet, though similar to that of Jupiter and Saturn for the abundant presence of hydrogen and helium, contains a high proportion of “ice”, such as water, ammonia and methane, along with traces of hydrocarbons .

Atmosphere, definition and study. A-Z index of Cognitio.


Uranus is also the coolest of the solar system, with a minimum temperature that can drop to -224 ° C. Like the other giant planets, Uranus has a system of planetary rings, a magnetosphere, and numerous satellites; seen from Earth, because of the planet’s inclination, its rings may sometimes appear as a concentric system surrounding the planet, or as in 2007 and 2008 appear to be cut. Uranus exploration was only done using the Voyager 2 probe and no further exploratory missions are currently planned at the site. To overcome the lack of direct information, variations in the atmosphere of the planet are studied through telescopic observation campaigns, in particular by using the Large Field Planetary Room on board the Hubble Space Telescope. The Voyager 2 probe reached the planet’s maximum approach on January 24, 1986, at a distance of approximately 81,500 km. The observations lasted only six hours, but allowed astronomers to learn Uranus much more than they had learned over 200 years of observations from Earth.

Astronomical observation, definition and study. A-Z index of Cognitio.

Astronomical observation

However, the initial analysis of the data was a huge disappointment: there were no parallel bands or clouds, as opposed to what had been observed by Earth. The atmosphere of a blue-green color was uniform and completely devoid of details. It was only thanks to the treatment of images that appeared both clouds and other formations. 

The probe discovered new moons, sent the first images of the rings to Earth and discovered geologic activity on the major moons: dark deposits at the bottom of frozen craters indicated the presence of dirty water due to volcanic activity. The standard model of the Uranus structure is divided into three layers: the rock layer (silicates, iron, nickel) in the center, an icy coat in the middle, and a gaseous layer of hydrogen and helium outside. The mass of Uranus is about 14.5 times that of Earth, making it the least massive of giant planets, despite its diameter, about four times that of Earth, is slightly larger than that of Neptune. The internal structure of Uranus means that it does not have a solid crust; the atmospheric gas becomes increasingly dense by moving inwardly and gradually converts into liquid. The atmosphere of Uranus is rather regular compared to other gigantic, even compared to Neptune, the most similar in other respects. When Voyager 2 approached Uranus in 1986, only a dozen cloud formations were observed on the planet. One explanation for this is the low internal warmth of Uranus compared to that of other giant planets.  It is highly unlikely that there may be anything to call life on Uranus. Uranus is a gaseous giant, and therefore does not have a definite solid surface. Even the atmosphere is unsuitable: beyond the composition it has pressures and prohibitive temperatures. On the surface the temperatures are very low, around -223 ° C, and where these may be acceptable, it is the pressure along with the lack of sunlight, and hence of a source of energy, to prevent advanced chemical processes underlying any form of life. The natural Uranus satellites known are 27, and among them the top 5 are: Ariel, Umbriel, Titania, Oberon, Miranda. Uranus also possesses a perceptible ring system, consisting of dark and powdered material up to 10 km in diameter.

Uranus, definition and study. A-Z Index of Cognitio.



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Uranus, definition and study. A-Z Index of Cognitio.