Mercury is often seen in the morning or evening - at this time it seems a bright star in the twilight sky.In ancient times, even we thought it was two different stars - peoples of the earth then, gave these "stars" two names - Gore and light Rogineya Buddha, Hermes and Apollo.
General
Mercury - the closest to the luminary of the planets of the solar system.It is the smallest of the entire "family", but has a very high density.Almost 80% of the mass of the object falls on the core.The diameter of Mercury is about 5000 kilometers.
Mercury rotates faster than the other planets.This happens so that it did not go away from its orbit.Mercury year - only 88 Earth days.At the same time around him during that time the planet rotates just half.Thus, the Mercurian day are 59 earth.From sunrise to sunset as passes and did 179 Earth days.
Despite the fact that the planet is bright enough, and the diameter of Mercury allows you to be visible from the Earth, we see it is not so often.This happens for the reason that Mercury is too close to the sun.To see it, so you can only at the time when he moves away from the sun at the maximum distance.
Mercury diameter slightly larger than the Moon, but its density is much higher.It is possible that center density - 8900 kg per cubic meter.This suggests that the core is composed of iron.And in this case, the core having a radius of 1800 km is ¾ planet radius.
Actually, it is the diameter of Mercury allows some scholars since the XIX century to assert that before the planet Venus was a satellite that was lost in the crash.It is possible that the disaster was a collision with another planet, in which Mercury was not only on its current orbit, but also received a lot of damage observed in the images of the planet today.
surface
Browse Mercury's surface was made possible in 1974 when flying past "Mariner 10" sent pictures.It turned out that the red planet is very similar to our moon."Earth" Mercury is covered with rocks and craters, including shaped diverging rays.These craters were formed by collisions with a lot of meteorites.Rocks also emerged at a time when the core of the planet shrank, pulling at the same time and bark.
As Mercury - the planet, the light emitting it can not.We see it as a star only because the planet's surface has good reflectivity - is visible from Earth reflected light of the sun.
atmosphere
Some signs indicate the presence of an atmosphere on Mercury.But it is much more - thousands of times - no charge than Earth.It does not allow to keep warm or protect the planet from over-heating.That is why in the world there is a huge difference between day and night temperatures.
Almost conditional Mercury's atmosphere is composed of helium, hydrogen, carbon dioxide, neon and argon, oxygen.Proximity to the luminary, the estimated impact on the planet of the solar wind.This increases the risk of an electric field of a planet twice more intense than the Earth, and thus much more stable.
temperature
Given the almost complete absence of the planet's atmosphere, surface heats and cools during the day at night is essential.Hemisphere tilted toward the sun, heating up to 440 degrees Celsius.In this hemisphere night, not able to keep the heat without air, it cools down to -180 degrees.
diameter
diameter of Mercury is 4878 kilometers.This is almost 2.5 times smaller than the size of our planet, but it is 1.5 times larger than the Moon.For a long time it was thought that Mercury's diameter in kilometers does not change.However, recent studies and data made spacecraft suggest that the size of its change.The new data have enabled astrophysicists to determine that the last 4 billion years have adjusted the volume of the planet.The diameter of the planet Mercury during this period decreased by 14 kilometers.The outer shell of the planet - it's just one plate, unlike Earth where the surface consists of several plates.
As a result of cooling and subsequent compression of the diameter of the planet Mercury's crust was significantly reduced.Moreover, this decrease is much greater than if the same conditions occur on the Moon or Mars.The data are transferred spacecraft "Messendzher" provide an opportunity to study the evolution of the planet.Perhaps soon we are waiting for new sensations.
Forecasts
Of course, the exact scenario of the future, no one can give.Enough only realistic assumption that a further cooling of the planet Mercury's diameter can be reduced further.
But there is a version, according to which in the distant future of our planet will face the system.Mercury or fall on the Sun, or crash into Venus.This, however, did not happen sooner than a billion years old.
Scientists from France have created a model of behavior of the solar system in the next 5 billion years.On the basis of the available data it is concluded that by 3.5 billion years of planetary orbits intersect, causing the collision.In this model, almost all of the planet can get close to the dangerous distance to the Earth, except Mercury, which is likely to fall to the sun.
Yet, most scientists acknowledge that the likelihood of such a future - only 1%.This model shows only what it is in principle possible.In addition, 3.5 billion years - it is a significant amount of time, and at that time, humanity is likely to be a completely still, as with what face.
