It's practically no secret that many celestial bodies revolve around the Sun, which, in addition to planets, also include their satellites, comets, asteroids and other particles. Modern scientists have managed not only to observe them through telescopes and other devices, but even to study their samples obtained through the use of probes. All this now allows us to confidently answer many questions about planets close to the Sun, their satellites and other celestial bodies.
General description of the planets of the solar system
There are a total of nine planets in our solar system. Each of them is distinguished by its astronomical and structural characteristics. Like the Earth, they all revolve not only around their own axis, but also around a common celestial body. The planets closest to the Sun are Mercury, Venus, Earth and Mars. They are also called "terrestrial planets". Their common characteristics are relatively small size,the predominance of solid elements in the structure, the absence of rings, as well as a small number of satellites. After them come the planets of the Jupiter group, which include Jupiter itself, as well as Saturn, Uranus and Neptune. They are characterized by a fairly dense atmosphere, as well as light components surrounding the core. Around each of them there are rings, consisting of fragmented substances, and numerous satellites rotate. As for Pluto, it is constantly in darkness, and some of the scientists do not consider it a planet at all.
Mercury
Almost every student knows what is the closest planet to the Sun. This is Mercury. In terms of size, it is in eighth place out of all representatives of the system. An interesting fact is that the satellites of Saturn and Jupiter (Titan and Ganymede, respectively) are larger in size. Mercury has a diameter of 4880 kilometers, and its orbit passes at a distance of almost 58 million kilometers from the Sun. In the entire history of this planet, only one ship flew to this planet (Mariner 10 in 1974-1975), so now there is information about only 45 percent of its surface. According to research by scientists, temperature fluctuations here range from 90 to 700 oK.
The closest planet to the Sun is somewhat reminiscent of the Moon. The fact is that there is no tectonic plate in it, and on the surface there are a large number of craters and huge abysses. In terms of such a parameter as density, Mercury is in second place in the system.after Earth. This planet has a weak magnetic field. Its power compared to the Earth is a hundred times smaller. Mercury has no satellites, and you can even see it with the naked eye.
Venus
The second planet, judging by the distance from the Sun, is Venus. In the case when such a criterion as magnitude is taken as the basis, it is in sixth place. Its diameter is more than 12 thousand kilometers, and the orbit passes 108 million kilometers from the Sun. The first spacecraft to approach Venus was Mariner 2 in 1962.
Compared to the Earth, Venus rotates very slowly. Due to the synchronization of its orbit and period of rotation, only one side of this planet is always turned towards us. Very often, Venus is called the "sister of the Earth", which is due to their great similarity. Indeed, its diameter is 95% of our planet, and its mass is 80%. The density and chemical composition are also quite similar. However, it should be noted that in many other parameters there are radical differences. There is every reason to believe that once there was a large amount of water on Venus, which eventually boiled away, so now it is completely dry. The planet has no magnetic field (due to slow rotation), as well as satellites. You can see it with the naked eye, because in our sky it is the brightest "star".
Earth
The third from the Sun is the Earth. Its diameter is 12,756.3 km, and the orbit passes bya distance of 149.6 million km from the heavenly body. Like other planets close to the Sun, it has a history of about 5.5 billion years. In the system, the Earth is considered the densest celestial body. Water covers 71% of its area. An interesting feature is that only here it exists in liquid form on the surface. Scientists suggest that this is largely due to the stability of temperature on our planet. The only natural satellite of the Earth is the Moon. In addition to her, many artificial bodies were launched into orbit.
Mars
Mars is in fourth place in terms of distance from the Sun and in seventh position in magnitude. Its orbit is located at a distance of almost 228 million km from the heavenly body, and its diameter is 6794 km. The first ship to fly to it was Mariner 4 in 1965. Like other planets close to the Sun, Mars boasts a rather original and interesting terrain. There are many craters, mountain ranges, flats and hills. The average temperature on Mars is about minus 55 degrees. You can even see it with the naked eye. As for satellites, this planet has two of them: Deimos and Phobos, which rotate not far from its surface.
