There are eight planets in our solar system. Pluto, which since its discovery in 1930 was considered a full-fledged ninth planet, in 2006 was "demoted" by the International Astronomical Union (IAU) to the title of a dwarf planet or asteroid. Mercury, the planet closest to the Sun, is named after the ancient Roman god, the patron saint of travelers, merchants and thieves. The name was given because of the great mobility, even the "fussiness" of the planet, which revolves around the Sun in 88 Earth days. Due to the proximity to our luminary, there are extreme conditions on Mercury that exclude the emergence and preservation of life of the Earth type.
Mercury: physical characteristics
Mercury - not only the planet closest to the Sun, it is also the smallest. The radius of Mercury is 2440 kilometers. This is less than the radius of Titan (moon of Saturn) and Ganymede (moon of Jupiter). If there were a sufficiently massive planet next to Mercury, then it would most likely be attracted by it and would also become a satellite. But he managed to avoid this fate, remaining in the status of the planet. Comparative characteristics of Mercury and Earth:
|Equator||15 330 km||40 000 km|
|Average radius||2439.7 km||6371 km|
|Surface area||74,800,000 sq. km||510,000,000 sq. km|
|Mass of the planet||3.33022x1023kg||5.9726x1024kg|
|Acceleration of gravity||3.7 m / s2||9.78 m / s2|
|Average density||5.427 g / cm3||5.5153 g / cm3|
|First space velocity||3.1 km / s||7.91 km / s|
|Second space velocity||4.25 km / s||11.186 km / s|
|Axis tilt||2, 11 ′||23 ° 26'21 ”|
|The volume of the planet||6.083x1010||10, 8321x1011|
|Distance from the Sun||46-70 million km||150 million km|
The daily temperature drops on the surface of Mercury are the largest in the solar system. This became possible due to the almost complete absence of the atmosphere and the loose state of the upper layers of the Mercurian soil, which makes it difficult to transfer excess heat into the interior of the planet. The average daytime temperature is about plus 350 degrees Celsius, at night - minus 170 degrees Celsius, that is, the daily fluctuations are 520 degrees. For comparison: although the second planet from the Sun - Venus - has an even higher daytime temperature (plus 470 degrees), but daily fluctuations due to a very thick and dense atmosphere and the presence of the "greenhouse effect" are almost absent or very insignificant.
Surface and interior of Mercury
The closest planet to the Sun has a surface that strongly resembles the lunar: it is also covered with a large number of craters formed from impacts of meteorites. A similar situation has developed due to a very thin atmosphere, which could protect the planet from strikes from space. Unlike the Moon, there are so-called escarps on Mercury - slopes hundreds of kilometers long. Presumably, they arose during the cooling of the planet, when it was compressed. As a result of this compression, the surface area has decreased by one percent.
According to the calculations of astrophysicists, Mercury has a liquid core with a high iron content, due to which the planet has a fairly strong magnetic field. The size of the core is up to 75 percent of the planet's diameter. The crust is about three hundred kilometers thick, and the mantle contains a high content of silicates. More accurate information about the state of the interior of Mercury is not yet available.
Investigation of Mercury
Mercury belongs to the planets visible from the Earth with the naked eye, therefore it was studied by the astronomers of Babylon and Ancient Greece. But due to the lack of telescopes, all studies for a long time were reduced to determining the parameters of the orbit, and, moreover, due to the close angular distance from the Sun, observation of Mercury is often difficult. In the 17th century, studies began with the help of telescopes, and in the 20th century, with the help of radio telescopes and interplanetary automatic stations. The first scanning of the planet's surface with a radio telescope was made in 1965. And the first spacecraft - "Mariner-10" - approached Mercury at a distance of 320 km in 1974.
Mercury remains the least explored terrestrial planet today. The start of the joint European-Japanese automatic station "BepiColombo" is scheduled for July 9, 2016. The station will deliver two research modules to the orbit of Mercury, one of which was created by Russia. The modules will revolve around the planet in highly elongated orbits: European - at a distance of 400 to 1500 km, and Japanese - from 450 to 15000 km. The modules are expected to operate in orbit for about a year..