The closest to the Sun planet mercury in our time remains one of the most poorly understood, despite the fact that watching it has involved the astronomers of the Ancient world. Small size and small distance from the sun do not allow today to obtain detailed information about a space object.
Mercury in numbers
The planet, named after the Roman god of commerce, is the smallest in the solar system. In size, it is inferior even to some satellites. The mass of Mercury is only 5.5% of the earth - 3.3 * 10 23 kg. The planet closest to the Sun is significantly inferior to ours and along the radius: 2,439.7 km versus 6371 km. It makes one revolution around the star in 88 days. At the same time, the Mercury sunny day lasts 176 earthly. In orbit, Mercury moves at an average speed of 48 km / s.
Remoteness from the star
The distance from the Sun to Mercury is estimated at an average of slightly less than 58 million kilometers. The orbit of the planet is greatly extended, so the exact value during the year varies significantly. At perihelion (the point of maximum approximation) the distance from the Sun to Mercury is 45.9 million km, in aphelion (the point of maximum removal) - 69.7 million km. The difference between these two positions is quite large. Being in perihelion, Mercury is closer to the Sun 1.5 times than in aphelion.
The distance separating the “winged” planet and the Earth also varies greatly. The range is from 82 to 217 million kilometers.
Features of the planet mercury is largely due to its unique position in the Solar system. According to scientists, the light from the time of planet formation reduced its momentum. This has led to a synchronization of the rotation of mercury around its axis and around the Sun. Stellar day here last 58,65 earth, accounting for two-thirds of the year on the planet. The result of these matches are so-called hot-longitude — two surface, appearing alternately turned to the Sun at the moment of passing the perihelion of the planet. The temperature in these meridians is extremely high even by the standards of mercury.
The planet is characterized by significant daily fluctuations: from +350 to -170 ºС. The difference of 520º is unique to our corner of the cosmos. One of the reasons that led to such a difference is the almost 100% absence of the atmosphere. Loose ground, which does not allow heat into the bowels of the planet, contributes to the warming of the air during the daytime and its very fast cooling at night.
The planet closest to the Sun is different from Earth and the absence of seasons. This feature of Mercury is obliged to the position of its axis: it is perpendicular to the plane of the orbit. As a result, there are places on the planet that are never illuminated by the rays of the sun. They are located near the poles. According to astronomical research, in these zones is a layer of ice up to two meters thick.
Strange behavior of the sun
The rotation of Mercury around the axis and around the Sun is characterized by another feature. Their speeds are not the same in time. Mercury rotates around its axis, almost always over a certain period of time overcoming the same number of kilometers. Movement in orbit occurs at a constantly changing speed. On the segment near the perihelion, it exceeds the angular velocity of rotation around the axis. This ratio is maintained for eight days. For a hypothetical observer on Mercury, it is expressed in the “inadequate behavior” of the Sun. At a certain moment, it freezes in the sky, and then begins to move in the opposite direction, from west to east. If the observer were at such a moment in longitude, at a distance of 90º from the “hot longitude”, he would have been able to see two sunset or sunrise lights.
The closest planet to the Sun is similar with his terrain with the Moon. Studies using the probe "Messenger" was opened by scientists many craters of mercury. The difference of the world from the earth of a satellite in the homogeneity of the surface. Mercury is covered with craters, the Moon is also characterized by a large difference in the topography of the surface of its two hemispheres.
Craters testify to the absence of significant movement of the planet's crust for the past three-four billion years of erosional processes. The latter suggests that the atmosphere on mercury is missing initially, from the moment of its formation.
All closer to the Sun is the planet Mercury. The light, one might say, protects it from too curious scientists. However, the rapid development of space technology allows us to hope that in a short time all the questions of astronomers related to Mercury will receive their answers. The launch of a new research station is planned for 2016.