Around the Sun are moving the eight largest celestial bodies - planets. In addition to the Earth, in the solar system there are such planets as Mercury - the closest to the sun, Venus - the second planet from the Sun, Mars, Saturn, Jupiter, Neptune, Uranus. This is the order of the planets. Previously, Pluto was also referred to planets, but since 2006 this space object has lost its status, and today it is considered a planetoid, a minor planet. Almost all space objects can be seen in the sky with the naked eye, only Uranus and Neptune can be viewed through a telescope.
The sizes of the planets and the sun
People have known about planets since ancient times. The closest neighbors of the Earth are Mars and Venus, whose radius is 6052 kilometers, the farthest - Uranus and Neptune.
All the celestial bodies of the solar system are divided into two categories. The first group includes objects of the Earth group, or the so-called internal planets closest to the Sun - these are Earth, Mars, Mercury and Venus. All these celestial bodies have a solid surface, they have a high density, despite the inner liquid core. The largest in this group is Earth.
The second category includes all other objects, called "giant planets." They are located farthest from the Sun, and the size of the planets of this group is much greater than the Earth. They are also called outer planets. For example, the weight of Jupiter is three hundred times the weight of the Earth. In addition, giant planets differ in structure from the objects of the earth group: they mainly consist of gases (hydrogen and helium), and this is similar to other stars. They are also called "gas giants."
The sizes of the planets affect their speed of rotation around their own axis, the duration of the day and night.
In addition to the described celestial bodies, the composition of our system includes planetary moons. A total of 54 satellites revolve around the planets. The moon is a satellite of the Earth, Mars and Neptune have two satellites each. Saturn has the most satellites - seventeen, and some of them are larger than the moon. Uranus and Jupiter have many satellites, and only Mercury and Venus are left alone.
Thousands of various small bodies still plow the Solar System along and across: comets, asteroids, millions of meteorites, particles of gas and dust matter, scattered atoms of various chemical elements, flows of atomic particles.
The asteroid belt is located between Jupiter and Mars. An asteroid is a small cosmic body. The sizes of asteroid planets vary from a few tens of meters to a thousand kilometers. The largest of them are Juno, Pallas, Ceres.
In general, all the cosmic bodies of the solar system are in equilibrium due to the attraction of the sun. They all revolve around the star in the same plane (along the ecliptic), and in the same direction. The exception is only some comets. Almost all celestial bodies rotate around their axis.
The mass of the Sun accounts for almost 99.80% of the mass of the entire solar system. The remaining mass is 99% taken over by gas giants (Saturn and Jupiter). According to astronomers, the size of our system is at least 60.0 billion kilometers - it is very difficult to imagine such a distance. Between the stars, the distance is measured in astronomical units. One a. e. equals the distance between the Sun and the Earth (approximately 150.0 million km).
To represent the scale of the solar system and the size of the planets, you can use the following model, the parameters of which will be reduced by a billion times. Thus, the Earth’s diameter will be 1.3 cm, the Moon will be located at a distance of 30 cm from it, Jupiter will be the size of a grapefruit, and a person can be compared to an atom. The diameter of the Sun will be one and a half meters, and it will be located 150 meters from the Earth. The nearest star in this model will be at a distance of forty thousand kilometers.