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 figures
The planet, named after the Roman god of commerce, is the smallest in the solar system. By its size, it is inferior even to some of the satellites. The mass of Mercury is only 5.5% of the Earth's - 3.3 * 10 23 kg. The planet closest to the Sun is considerably inferior to ours and along the radius: 2439.7 km against 6371 km. One revolution around the star she performs for 88 days. At the same time Mercurian solar day lasts 176 terrestrial. In orbit, Mercury moves at an average speed of 48 km / s.
Distance from the sun
The distance from the Sun to Mercury is on average estimated to be slightly less than 58 million kilometers. The orbit of the planet is strongly elongated, so the exact meaning varies substantially throughout the year. 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 distance) is 69.7 million km. The difference between these two provisions is quite large. Being at 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 520 is unique for our corner of space. One of the reasons that led to such a difference is practically a 100% absence of the atmosphere. To warm up the air in the daytime and to its very rapid cooling at night is also facilitated by a loose soil that does not let heat into the bowels of the planet.
The planet closest to the Sun is different from Earth and the absence of seasons. This feature of Mercury is due 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 sun's rays. They are located near the poles. According to astronomical studies, in these zones there 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 one more feature. Their speeds are not the same in time. Around its axis, Mercury rotates, almost always over a certain period of time overcoming the same number of kilometers. Movement in orbit occurs with an ever-changing speed. On the segment near perihelion it exceeds the angular velocity of rotation about 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 some point it freezes in the sky, and then starts moving in the opposite direction, from west to east. If the observer was at such a moment at a longitude, distant from "hot longitude" by 90º, he could see two sunset or sunrise.
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 the closer to the Sun is the planet Mercury. The light, one might say, protects him from too curious scientists. However, the rapid development of space technology makes it possible to hope that soon all questions of astronomers related to Mercury will receive their answers. The launch of a new research station is planned in 2016.