Mercury can often be seen in the morning or evening hours - at this time it seems like a bright star in the twilight sky. In ancient times they even believed that these were two different stars - the peoples who inhabited the Earth then gave these "stars" two names - Horus and Light, Roginea and Buddha, Hermes and Apollon.
General information
Mercury is the closest to the luminary of the planets of the solar system. He is the smallest of the entire "family", but has a very high density. Almost 80% of the total mass of the object is in the core. The diameter of Mercury is almost 5 thousand kilometers.
Mercury rotates faster than other planets. This happens so that he does not leave his orbit. The year of Mercury is only 88 earth days. At the same time, around this time the planet rotates only a half times. Thus, the Mercury day is equal to 59 Earth. From sunrise to sunset, 179 earth days pass at all.
Despite the fact that the planet is quite bright, and the diameter of Mercury allows it to be visible from the Earth, we do not see it so often. This happens because Mercury is too close to the Sun. Thus, it is possible to see him only at a time when he is moving away from the body to a maximum distance.
The diameter of Mercury is slightly larger than the Moon, but its density is much higher. It is possible that the center density is 8900 kilograms per cubic meter. This suggests that the core consists of iron. Moreover, in this case, the core, having a radius of 1800 km, is ¾ of the radius of the planet.
Actually, it is precisely the diameter of Mercury that allows some scientists since the 19th century to claim that earlier this planet was a satellite of Venus, which was lost as a result of the disaster. It is possible that this catastrophe was a collision with another planet, as a result of which Mercury not only ended up in its current orbit, but also received a lot of damage that is observed today in the images of the planet.
Surface
It became possible to make out the surface of Mercury in 1974, when Mariner 10 flying by sent photos. It turned out that the surface of the red planet is very similar to our moon. The "Earth" of Mercury is dotted with rocks and craters, including those having the form of diverging rays. These craters were formed from collisions with many meteorites. Rocks also appeared at a time when the core of the planet was shrinking, while pulling together the crust.
Since Mercury is a planet, it cannot emit light. We observe it as a star only because the surface of the planet has a good reflectivity - the reflected light of the Sun is visible from the Earth.
Atmosphere
Some signs indicate the presence of atmosphere in Mercury. But it is much more - a thousand times - discharged than the earth. It does not allow you to retain heat or protect the planet from excessive heat. That is why on the planet there is a huge difference between daytime and nighttime temperatures.
The almost conventional atmosphere of Mercury consists of helium, hydrogen, carbon dioxide, neon and argon, oxygen. Proximity to the luminary suggests the influence of the solar wind on the planet. This increases the likelihood of a planet having an electric field that is twice as intense as the earth’s, and is much more stable.
Temperature
Given the almost complete absence of the planet’s atmosphere, the surface heats up during the day and cools significantly at night. The hemisphere, turned to the Sun, glows to 440 degrees Celsius. At the same time, the night hemisphere, unable to retain heat without an atmosphere, cools down to -180 degrees.
Diameter
The diameter of Mercury is 4878 kilometers. This is almost 2.5 times smaller than the size of our planet, but at the same time 1.5 times larger than the moon. For a long time it was believed that the diameter of Mercury in kilometers does not change. However, recent research and data transmitted by the spacecraft indicate that its size is variable. New data made it possible for astrophysicists to find out that the last 4 billion years have made adjustments to the volume of the planet. The diameter of the planet Mercury during this time decreased by 14 kilometers. The outer shell of the planet is just one plate, unlike the Earth, where the surface consists of several plates.
As a result of cooling and subsequent compression of the crust, the diameter of the planet Mercury was significantly reduced. Moreover, this decrease is much more significant than under the same conditions occurs on the Moon or Mars. The data transmitted by the Messenger spacecraft provide an opportunity to study the evolution of the planet. Perhaps soon new sensations await us.
Forecasts
Of course, no one can give an exact scenario for the future. Only the assumption that with further cooling of the planet the diameter of Mercury may still decrease is quite realistic.
However, there is a version according to which in the distant future the planets of our system will collide. Mercury will either fall on the Sun or crash into Venus. This, however, will not happen any sooner than in billions of years.
Scientists from France have created a model of the behavior of the solar system over the next 5 billion years. Based on the available data, it was concluded that after 3.5 billion years, the orbits of the planets intersect, provoking a collision. In this model, almost all planets can approach a dangerous distance from the Earth, except for Mercury, which, most likely, will fall on the Sun.
But still, most scientists recognize that the likelihood of such a future is only 1%. This model shows only that it is, in principle, possible. In addition, 3.5 billion years is quite a significant time, and at that time, it would be quite probable for humanity to be completely alike about what it was faced with.