About 5 billion. In the very center of the sun formed, around it - the planet.

Structurally, our star system is divided into two regions: four planets of the earth group and the asteroid belt - the inner part. Four gas giants plus objects beyond Neptune - the outer part.

Due to the fact that Pluto, since 2006, is not considered a planet, a class of small bodies called “plutoids” has arisen.

Earth Planets of the Solar System

This is a group of celestial bodies characterized by high density:

• Mercury.
• Venus.
• Land.
• Mars.

To a greater extent, their composition is formed by solid materials: silicates - rock-forming minerals and metallic iron.

The internal structure of the terrestrial planets: Iron-nickel core, silicate mantle. Rich in silicates with an admixture of incompatible elements - the bark. In Mercury, it is destroyed by meteorites.

The chemical composition of the planets is represented by the following substances:

• Aluminum.
• Iron.
• Oxygen.
• Silicon.
• Magnesium.
• Heavy elements.

Interesting fact: these planets do not have rings!

Solar System Planets - Gas Giants

Planets from the outer group: Neptune, Saturn, Uranus, Jupiter have a fairly large volume. But low density, since they contain: ammonia, hydrogen, helium, methane and a number of light gases. Two of the four extreme celestial bodies contain more ice than their neighbors.

This suggests the sequence of occurrence of the solar system:

• The first was the sun.
• The second is the planets of the earth group.
• Thirdly, the first pair of giant planets.
• Fourth - Uranus and Neptune.

Due to the small specific gravity, gas giants have compression in the region of the poles and have a high daily rotation speed. They emit a significant amount of their own thermal energy into space, while reflecting cosmic rays well.

Huge celestial bodies have an atmosphere in which hurricane winds blow at speeds of up to one thousand meters per second (Saturn - 500m / sec.). Gigantic gas vortices arise: a large red spot on Jupiter, a large dark spot on Neptune, small spots on Saturn.

The structure of the gas planets is layered. It is possible that it contains a stone or metal core and hydrogen is present in the form of a metal.

Interesting fact: the mass of gas giant satellites is only one ten thousandth of them.

Dwarf planets of the solar system

In addition to the eight planets, there are many other celestial bodies in the solar system. A number of them, according to the classification of the union of astronomers, is called dwarf planets. These are cosmic bodies: orbiting the Sun, spherical in shape (formed under the influence of gravitational forces), no one's satellites, unable to attract small objects of their own orbit.

Today they include:

• Pluto is a former planet from the Kuiper belt, having five of its own satellites.
• Haumea is an egg-shaped body with the highest rotation speed in the inhabited planetary system. It is also located in the Kuiper belt and is the owner of two satellites.
• Makemake is the largest object in the Kuiper belt with one natural satellite.
• Eris - is located in the area of ​​the scattered disk.
• Ceres - from the asteroid belt.

Almost fifty more celestial bodies claim the title of "dwarf". The boundaries of the planetary system of our habitation are not established even approximately, and space research continues.

Solar system planets in order

The beginning of the second millennium AD brought significant adjustments to the harmonious picture of the universe. It turns out that at the very beginning of formation, the solar system looked very different.

For example: in its inner part could be located from 50 to 100 planets; and the outside was much smaller and more compact.Further disasters led to the redistribution of mass and migration of bodies within the system. As confirmed by the study of stellar systems of nearby galaxies. But so far this is just a beautiful hypothesis, requiring confirmation by scientific facts. Our star-planet system is quite stable. No planetary migration is expected in the next few billion years.

The first planet from the Sun - Mercury

The smallest planet closest to the Sun - Mercury, got its name for the speed and speed of movement. The "messenger of the gods" cannot be slow.
The period of its orbit is 88 Earth days, and around its own axis - 58 days 15 hours 30 minutes, which is 2/3 of the Mercury year. During this time, the planet approaches the Sun at a distance of 46 million km, and moves away - at 69.8 million km.

Physical Parameters of Mercury:

• Mass - 3.33 · 1020 tons = 0.055 Earth masses.
• Volume - 6, 083 · 1019 m3 = 0.056 earth volume.
• Density - 5427 kg / m3 = 0.984 specific gravity of earth soil.
• Diameter - 4879.4 km = 0.383 of the diameter of our planet. Interestingly, it remains the same both at the poles and at the equator.
• The speed of orbital rotation ranges from 38.7 to 56.6 km / s.
• There are no seasons on the planet.
• The temperature fluctuation range reaches 620 ° C.

The atmosphere of Mercury is very rarefied and contains atoms brought by the solar wind or torn from the surface of the planet by it.

Mercury structure

• Liquid iron-nickel core with a very high iron content, a radius of 1800 km.
• Silicate mantle, up to 600 km thick.
• The crust destroyed by meteorites. Data on its thickness is contradictory. According to some sources: 100 - 300 km, according to others: 15 - 37 km.

The second planet from the Sun - Venus

Our closest neighbor, Venus, is named after the Roman goddess and beauty, in many ways similar to Earth. The star was represented by ancient observers as two different celestial objects.

She has a capricious character: spinning in the opposite direction (relative to her “brothers” in the star system) is counterclockwise. And it’s very slow: the revolution around its axis (the average starry day) lasts 243 days and 26 minutes. While a year on Venus has a duration of 224.7 Earth days.

Interesting fact: New Year on Venus - every day. And sometimes there may even be two.

The movement of the planet around the Star takes place in a practically circular orbit (eccentricity = 0.0067), at a distance of about 108 million km. The difference between the farthest and closest to the Sun, the points of motion of Venus, does not exceed 1.3%.

Physical data of Venus

• Mass - 4.87 · 1021 tons = 0.815 Earth masses.
• Volume - 9.38 · 1020 m3 = 0.857 of the earth's volume.
• Density - 5243 kg / m3 = 0.951 specific gravity of earth soil.
• Diameter - 12103.6 km = 0.949 of the diameter of our planet. Like Mercury, polar compression is zero.
• The speed of movement in orbit is 35 km / s.
• The seasons do not change, due to the small angle of inclination of the axis of rotation of the planet to the plane of rotation around the Sun.
• The temperature on the surface of Venus reaches + 464 ° C.

The atmosphere of our nearest “neighbor” is extremely dense and consists mainly of CO2.
The internal structure of the planet is standard: crust, mantle, core. The only feature indicating a solid state of the nucleus is the absence of a magnetic field.

Third Planet from the Sun - Earth

The largest of the inner planets. A name that literally means that which is below and has no deification. However, it is here that life exists in all its diversity.

Astronomical parameters played a small role in this:

• The orbit period is 365.25 days.
• One revolution around its own axis lasts 24 hours without 3 minutes and 56 seconds.
• It is approaching the Sun by 147 million. It is moving away from it by 152 million km.

Physical characteristics:

• Age - 4.54 billion years.
• Mass - 5.97 · 1021 tons.
• Volume - 10.83 · 1020 m3.
• Density - 5515 kg / m3.
• Diameter - 12742 km.
• The orbital speed is 29.78 km / s.
• Seasonality In this regard, the Earth was lucky: winter, spring, summer and autumn succeed each other, creating favorable conditions for the life of organisms.
• Temperature difference: from - 89.2 ° С (July 21, 1983, Vostok station, Antarctica) to + 58.4 ° С (September 13, 1922, Al-Aziziya, Libya; the same temperature was recorded at the same time in Saudi Arabia).

The satellite is the Moon, if you do not take into account more than 8 thousand artificial aircraft flying around our planet.

Speaking about the Earth, one cannot ignore a particularly interesting fact: its surface is more than 70% covered with water resources that are in liquid form (there are also polar ice shells). There is no such thing anywhere else in the solar system.

The fourth planet from the Sun - Mars

The red planet bears the name of the Roman god of war, assigned to it by association with the “red” shade of the surface. Two satellites of Mars were named after the sons of another war god - the ancient Greek: Phobos - in translation means "fear", Deimos - no less ruthless "horror".

The duration of the Martian year is 686.98 days of the Earth. The period of revolution around its own axis (stellar day) is 24 hours 37 minutes 23 seconds. The planet’s sunny day is 2.5 minutes longer than stellar days and 2.7% more than Earth's.

Characteristics of mars

• Age - 4.65 billion years.
• Mass - 6.42 · 1020 tons = 0.107 Earth masses.
• Volume - 1.63 · 1020 m3 = 0.151 earth volume.
• Density - 3933 kg / m3 = 0.714 of the specific gravity of the Earth.
• Diameter: 6752.4 km = 0.531 Earth - polar; 6792.4 km = 0.532 terrestrial - equatorial.
• The orbital speed is 24.13 km / s.
• Seasonality The Martian seasons are special: in the northern hemisphere - long cold spring and summer; in the south, on the contrary, they are warm and short.
• Temperature difference: from - 153 ° С (in winter at the poles) to + 20 ° С. (The record number obtained by the rover Spirit + 35 ° C).

Mars has a rarefied atmosphere. Which leads to the constant occurrence of dust storms and vortices, covering its surface for a long time. There is a weak magnetic field on the planet. This can be explained by the structural features of the iron core: in the center it is solid, and on the outer periphery it is liquid.

Fifth Planet from the Sun - Jupiter

Jupiter is the largest planet in the solar system, named after the ancient Roman supreme god.

Jupiter mass:

• 2.5 times (71.16%) more than the mass of all other planets orbiting our luminary.
• 318 more than the mass of the Earth.
• 1000 times less than the mass of the sun.
• And the dimensions are such that the Earth in comparison with it looks like a small "crumb." The radius in the equator region is 71.4 thousand km, which is 11.2 times greater than the earth.
• A year on Jupiter lasts 12 Earth years, and a day lasts only 10 hours. The average distance to the Sun is 778.6 million km.

Interesting fact: according to astronomers, it is the “elder brother” who acts as the protector of our planet from cosmic impacts of arriving celestial bodies.

The phenomena of the planet:

• Winds blowing at a speed of more than 160 m / s.
• Atmospheric stripes.
• The big red spot is a hurricane, known since 1664.
• A small red spot is a newly formed giant whirlwind.
• 79 satellites, shadows from which heat the planet!
• Thousands of kilometers of colossal lightning, of huge energy power.
• Belts of increased radioactivity.
• Steady high brightness auroras.
• Large x-ray spot.
• Temporary moons!
• Weak rings due to their occurrence of volcanic activity of satellites.

Sixth planet from the sun - Saturn

The second largest planet in the solar system, bearing the name of the agricultural god of ancient Roman mythology. Its geometrical compression of the radius is unique for the whole system:

• 54,400 km - in the vicinity of the poles.
• 60 300 km - at the equator.
• The mass of the planet is 5.68 · 1023 tons = 95 masses of the Earth = 21.31% of the mass of the planets of the solar system.

Astronomical parameters of Saturn

• The period of revolution around the Sun is 29.5 years.
• The average distance to the Sun is 1430 million km.
• The speed of rotation around its own axis is different! At the equator, it is higher, which is explained by the gas composition of the planet. The accepted length of the day is 10 hours 34 minutes.

Interesting features

• Wind speed reaches 1800 km / h.
• The magnetic field has a length of up to 1 million km.
• 82 satellites.
• The most noticeable rings.
• The large white oval is an atmospheric phenomenon that appears with a frequency of 30 years.
• Ring Northern Lights.
• Cloudy hexagon at the North Pole, retaining its almost regular shape, for 20 years of continuous rotation!

Seventh planet from the Sun - Uranus

The seventh planet of the solar system, discovered through a telescope by the English astronomer W. Herschel, did not immediately get its name. Nevertheless, the name of the ancient Greek god was assigned to her. The period of the revolution of Uranus around the Sun lasts 84 Earth years, and the stellar days change every 17 hours and 14 minutes.

The mass of the planet is:

• 3.25% of the total planetary mass of our star system.
• 8.68 · 1022 tons = 15.54 Earth masses.
• Moreover, it is the least massive of the gas giants, since a significant amount of ice is present in its composition.

An interesting feature is the inclination of the axis of rotation. The planet, as it were, "lies on its side upside down, and at the same time rotates in the opposite direction from orbital motion."

Currently, Uranus has 13 rings and 27 satellites. Perhaps further studies will make some adjustments to these data.

Eighth Planet from the Sun - Neptune

The extreme planet of the solar system, named after the god of the seas. She spends almost 165 years to go in orbit, while she turns around her own axis and manages in 16 hours of Earth time.
Neptune owes its appearance to the mathematical calculations of the Frenchman W. Le Verrier.

Physical parameters of the planet

• Mass - 1.02 · 1023 tons = 17 Earth masses = 3.84% of the mass of the planets of the Solar system.
• Diameter - 49530 km = 4 Earth diameters.
• 5 rings.
• 14 satellites.

The atmospheric features of Neptune are such that they allow the winds to accelerate to 600 m / s. This is a record figure in the system. In addition, a large dark spot, a vortex formation similar to that located on Jupiter, was discovered on the surface of the planet.

Pluto - Dwarf Planet

The largest of the dwarf planets, named after the ancient Roman god of the underground kingdom of the dead, moves around the Sun in a retrograde orbit.
Pluto needs 248 years to complete its annual orbit. The duration of the day is 6.4 earth days and nights.

Physical Parameters of Pluto

• Mass - 1.3 · 1019 tons = 0.0022 Earth masses.
• Diameter - 2376 km.

It should be noted that these data have been repeatedly specified and do not claim to be completely objective. The planet has 5 natural satellites. One of them, Charon, is so large and close that some astronomers classify them as a double planet.

Interesting fact: planet name, proposed by an eleven-year-old girl: Venice Burnie.

Ninth planet

It is assumed that the list of planets in the solar system is not yet complete. Somewhere in the region of the scattered disk (a remote region of our star system), another planet may exist. It is she who can explain some anomaly in the behavior of transneptune bodies.
This interesting hypothesis was expressed in 2014 by astronomers C. Trujillo and S. Sheppard, additionally substantiated in 2016 by K. Batygin and M. Brown.

It is assumed that its mass is 10 times greater than the mass of the Earth, and the period of revolution around the Sun can last 20,000 years!

"Discovery" and exploration of the solar system

Man began to explore the outer space from ancient times. Milestones of this path:

• BC and at the very beginning of its astronomers had to use only their vision and the good location of the objects of the heavens.
• Everything changed in 1610, thanks to the creation of the first Italian telescope by the great Italian Galileo Galilei.
• October 4, 1957.Launch of the first in the history of mankind artificial satellite Sputnik-1.
• April 12, 1961 is a significant date in the history of our civilization. Yuri Alekseevich
• Gagarin - the first person to be in space.
• July 21, 1961 Neil Armstrong sets foot on the moon.

These are the most important events in the study of our star system. Besides:

• Many spacecraft launched.
• Created artificial satellites of the planets.
• The surface of celestial bodies is "plowed" by rovers and rovers.
• Powerful telescopes have been put into orbit.
• The International Space Station has begun work.

And this is just the beginning. The Pioner-10 automatic interplanetary station, which launched on March 3, 1972, was able to leave the Solar System! Perhaps in a couple of million years she will reach the vicinity of the star Aldebaran!