The solar system is the planetary system made up of the Sun and the celestial elements that are held together with the Sun by gravity. The Sun is a G2-class main sequence star 1.39 million kilometers in diameter. The Sun represents 99.86% of the mass of the solar system and is the closest star to Earth.
The solar system is located in the Local Interstellar Cloud, located in the Local Bubble of the Orion arm, within the Milky Way . The Milky Way is between 150 and 230 thousand light years in size and has between 100-400 billion stars. For reference, there is no planet in our solar system that is more than one light year from the Sun.
In the space between these celestial bodies is interplanetary matter. By one definition, the solar system is bounded by the heliopause, the edge of the heliosphere.
How Is the Solar System Formed?
In addition to the Sun, the Solar System contains eight planets, five dwarf planets, more than one million known asteroids, 644 planet moons, dwarf planets, and asteroids, and 3,701 known comets. Most of these objects revolve around the Sun in orbits with small inclinations relative to the ecliptic.
Most of the large elements orbiting the Sun move in the same virtual plane, called the ecliptic plane.
The Sun, the Central Star of the Solar System
The sun is the central and only star in our planetary system and is the source of solar energy.
The sun contains by its attraction all the planets of the solar system that orbit around it; in addition to other bodies that belong to him.
It is a medium star but, due to its proximity, it is the only star that can be seen with the naked eye in its circular shape.
The Sun emits energy in the form of radiation from the nuclear fusion reactions of hydrogen atoms that take place inside it. This energy is vital for life, as they allow the Earth to be kept in temperature ranges suitable for life and so that some basic elements of the food chain can photosynthesize.
It is estimated that the Sun was formed about 5000 million years ago and that it is in the middle of its life.
Planets of the Solar System
The solar system includes:
- Terrestrial planets: Mercury, Venus, Earth, Mars.
- Giant planets: Jupiter, Saturn, Uranus, Neptune
All the planets and most elements of the solar system rotate around the Sun in the same direction that our central star rotates (counterclockwise when viewed from the Sun's North Pole).
Most of the planets revolve around their axis in the same direction that they revolve around the Sun with the exceptions being Venus and Uranus.
The orbits of objects around the Sun are described by Kepler's laws. According to them, each object rotates on an ellipse, in one of whose foci is the Sun.
Satellites of Planets and Moons
Most of the planets in the solar system have their own subordinate systems. Many are surrounded by satellites, some of the satellites are larger than Mercury.
The four largest planets are gas giants. These planets also have rings, thin bands of tiny particles that rotate in very close orbits almost in unison.
What Are Dwarf Planets?
A dwarf planet is a spherical object that moves in a heliocentric orbit, but has not cleared the surrounding space.
What Are the Minor Bodies of the Solar System?
A minor body in the solar system is a celestial body that orbits around the Sun and is not a planet, a dwarf planet, or a satellite. The minor bodies of the solar system include: asteroids (small planets), meteorites and meteorite bodies, comets.
The minor bodies of the solar system are grouped into:
- Asteroid belt.
- Trans-Neptunian objects and the Kuiper Belt.
- Oort cloud.
What Is the Origin of the Solar System?
According to modern thinking, the solar system was formed about 5 billion years ago as a result of the accumulation and compression by gravity of a cloud of gas dust.
In the compression process, the dimensions of the gas and dust cloud decreased and the rotation speed of the cloud increased. Most of the mass had been concentrated in the center and it began to heat up much more than the surrounding disk.
Due to the rotation, the compression speeds of the clouds parallel and perpendicular to the axis of rotation were different, which caused the flattening of the cloud and the formation of a characteristic protoplanetary disk and a hot, dense protostar in the center. The planets were formed by accretion of this disk.
In 50 million years, the pressure and density of hydrogen in the center of the protostar became high enough to start a nuclear fusion reaction of hydrogen atoms. This nuclear energy is the origin of solar energy.
As the Sun burns its hydrogen fuel reserves, the energy released to support the nucleus tends to run out, causing the Sun to contract. This increases the pressure inside and heats the core, thus accelerating the combustion of the fuel.