Our solar system is at the center of the milky way galaxy, where it does not have a static position, but instead performs a rotation every 200 million years.
The solar system, as a very small part of the milky way, consists of different “stars”.
The sun
It is a medium-sized star with a diameter of almost 1.4 million kilometers (it could contain more than a million Earths inside it). It makes up more than 99% of the total mass of the solar system. The Sun is a gigantic nuclear melting pot of gas, which incandesces at temperatures of over 300 million degrees. In this process, hydrogen is converted into helium and 4 million tons of mass are converted into energy every second. Only about half a trillionth of the total solar radiation reaches the Earth.
The planets
In the solar system, there are nine planets with different sizes and orbits. The planet Mercury, which has a diameter of almost 5,000 kilometers, is the smallest planet and is the closest to the sun, with an orbital period of 3 months. In contrast, Jupiter, with a diameter of 140,000 kilometers, is the largest planet. It circles the sun in fifth position every 11 ¾ years. Pluto, which is 40 times further away from the sun than the earth, takes almost 250 years to circle the sun. The other planets are Venus, Earth, Mars, Saturn, Uranus and Neptune.
The Earth
With a diameter of approximately 12,700 kilometers, the Earth is the fifth largest planet and the third closest to the sun. The Earth moves around the sun in 365 ¼ days on a slightly elliptical orbit. Two intrinsic components of the Earth's motion are responsible for the change of day and night and the seasonal change of each year.
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On the one hand, the earth performs a spinning motion around its own axis, taking 24 hours to complete one rotation, corresponding to one day.
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On the other hand, the Earth's axis is tilted about 23.5 degrees relative to the orbit around the sun, causing one hemisphere to receive more sunlight and heat than the other for half a year. The summer season lasts on the side of the Earth tilted towards the sun, and the winter season on the side tilted away from the sun.
The gravitational forces of the sun and the moon cause a circular precession of about 12 meters per day at the earth's poles, which results in a change in the earth's inclination every 26,000 years.
Satellites and the Moon
They orbit the planets of the solar system as satellites. There are 32 satellites in all, with 12 belonging to Jupiter, 10 to Saturn, 5 to Uranus, 2 each to Neptune and Mars, and 1 to Earth – the Moon. The largest satellites are the moons of Jupiter and Saturn.
The moon as Earth satellite has a diameter of ¼ of the Earth, 1/81 of its weight and 3/5 of its density. The moon needs 27.3 days for one orbit around the Earth, and 29.5 days for rotation around its own axis. The fact that we always see the same side of the moon from the Earth, with the exception of an area of 18%, results from both moon movements. The moon's surface is covered with craters ranging in diameter from a few meters to 250 kilometers and with rim hills up to 4570 meters high. Bizarre rock formations, fine-grained dust and sand cover the moon's surface.
Comets
As the oldest parts of the solar system, the comets fly around the sun in elliptical orbits. When they approach the sun, the comet's tail glows due to contact with the solar winds.
Asteroids and meteors
Asteroids are irregularly shaped objects ranging in size from 1 to 480 miles. Most of the 1600 asteroids are found in orbits between Mars and Jupiter and are thought to be the remains of an earlier planet that broke apart.
Meteoroids are smaller than asteroids, some no larger than a grain of dust. Millions of meteoroids enter the Earth's atmosphere each year, where they heat up and glow, but some may reach the surface. Over 30 elements have been identified in meteorites.
