What is the solar system?

The solar system is a collection of all celestial bodies centered on the sun and constrained by the sun's gravity. Including eight planets (from close to the sun to far away from the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune), as well as at least 173 known satellites, five confirmed dwarf planets and hundreds of millions of small bodies in the solar system.

Broadly speaking, the solar system includes the sun, four inner planets similar to the earth, an asteroid belt composed of many small rocks, four giant outer planets filled with gas and a second small celestial body area called the Kuiper Belt. At present, there are eight planets in the solar system, namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Extended data:

The main structure of the solar system:

1, sun

The sun is the parent star of the solar system, the only celestial body in the solar system that emits light by itself, and the most important and important member.

2. Interplanetary matter

In addition to light, the sun constantly sends out a stream of electrons (plasma), which is called the solar wind. The speed of this particle flow is 6.5438+0.5 million kilometers per hour, forming a thin atmosphere (solar circle) in the solar system, with a range of at least 654.38+0.000 astronomical units (heliopause), which is what we call interplanetary matter.

3. Inner solar system

Traditionally, the inner solar system is the name of the region of terrestrial planets and asteroid belts, which is mainly composed of silicates and metals. This area is squeezed very close to the sun, and the radius is shorter than the distance between Jupiter and Saturn.

4. Earthlike planets

Mercury (0.4 astronomical unit) is the closest planet to the sun and the smallest planet (0.055 earth mass). It has no natural satellites, and the only known geological features are folded ridges that may have been produced during early history and contraction, except for impact craters.

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