The word "astronomy" has Greek origin, and it was created from the Greek words “astro” + “nomos”, which together mean “the law of the stars”. Astronomy is a science that studies the origin and evolution, as well as the physical and chemical properties of all objects outside of Earth's atmosphere.

Part of the galaxy generated by the action of the gravitational force of the Sun is called the Solar planetary system.

General characteristics of the Solar Planetary System

-The Sun is the central Star

-In addition to the Sun, the solar system consists of planets, dwarf planets, satellites, asteroids, meteoroids, comets, objects in the Kuiper belt and interplanetary material

-Dominant gravitational influence comes from the Sun

- All objects in the Solar System move around the Sun along elliptical paths (orbits)

-The planets are the largest objects and many have their followers - satellites. The largest are Ganimed (Jupiter), Titan (Saturn) and Kalisto (Jupiter)

Тhе Sun is 149.6 mil. km from the Earth. It consists of six zones: the core, the radiation zone, the convective zone, the photosphere, the chromosphere and the corona. The energy is generated in the core and transmitted to the surface by radiation and convection.

Mercury is the smallest planet in the Sun's system and closest to the Sun. One day on Mercury is equal to 59 days on Earth, and a year lasts the same as 88 Earth days. It has a solid, rocky surface covered with craters.

Venus is a bit smaller than Earth. One Venus day is longer than one Venus year. One Venus day is comparable to 243 earth days and the period of the revolution of 225 earth days. It rotates in the opposite direction as Earth. Venus’ mass, density and gravity is similar to Earth’s and it’s atmosphere is mostly comprised of carbon dioxide.

Earth is the the only known planet (so far) where life exists. The surface of the planet is rocky and 70% of the planet's surface is covered by water. There is a core which is made of iron and nickel. Around the core, there is a rocky cover. The earth also has an atmosphere, which contains 78% nitrogen, 21% oxygen, and 1% of other elements. Earth has one satellite – our moon.

Mars’ rotation period is similar to the Earth (one day on Mars lasts just over 24 hours). The year on Mars lasts 687 earth days. Its surface is rocky and dry. Mars has visible seasonal changes and has two known satellites, Fobos (Phobos) and Deimos.

Jupiter is the largest planet in the solar system. It is a gaseous planet mostly composed of ammonia. In 1979, rings around Jupiter were discovered. Of Jupiter's 67 known satellites, the largest are Europe (Europe), Ganimed (Ganymede), and Kalisto (Callisto).

Saturn is built mostly of hydrogen and helium. By volume it is 755 times larger than Earth. In the upper layers of the atmosphere, winds on Saturn reach 500 miles/second, which is five times faster than the fastest winds on Earth. These winds cause the formation of yellow and golden clouds around the planet. Due to strong pressures, the inner core of the planet is in solid state. The overheated core is a mixture of hydrogen in liquid and molten metals. The outer layer of the planet is made of hydrogen in a liquid state. Saturn's magnetic field is 578 times stronger than the Earth's magnetic field. Saturn has 62 satellites. With a diameter of 5,150 km, the satellite called Titan is second largest satellite in the solar system.

Uranus rotates retrograde, from the east to the west, and the axis around which it rotates is at an angle of 980 to the orbital plane, so it appears to roll on its side during the revolution. The atmosphere is mostly made of hydrogen and helium. It has 27 satellites, of which Oberon and Titania are the largest.

Neptune is made of ice. One year of Neptune lasts for 165 Earth years and the day last for 16 hours. The winds on Neptune are nine times stronger than the winds on Earth and its magnetic field is 27 times stronger than Earth’s. Neptune has 14 satellites. The greatest is Triton.


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