planets solar system- a bit of history

Previously, a planet was considered to be any body that revolves around a star, glows with light reflected from it, and has a size larger than that of asteroids.

Also in Ancient Greece mentioned seven luminous bodies that move across the sky against the background of fixed stars. These cosmic bodies were: Sun, Mercury, Venus, Moon, Mars, Jupiter and Saturn. Earth was not included in this list, since the ancient Greeks considered the Earth to be the center of all things.

And only in the XVI century Nicolaus Copernicus in his scientific work titled "On the Revolution of the Celestial Spheres" came to the conclusion that not the Earth, but the Sun should be in the center of the planetary system. Therefore, the Sun and the Moon were removed from the list, and the Earth was added to it. And after the advent of telescopes, Uranus and Neptune were added, in 1781 and 1846, respectively.
Last open planet The solar system from 1930 until recently was considered to be Pluto.

And now, almost 400 years after Galileo Galilei created the world's first telescope for observing stars, astronomers have come to the next definition of a planet.

Planet- this is a celestial body that must satisfy four conditions:
the body must revolve around a star (for example, around the Sun);
the body must have sufficient gravity to be spherical or close to it;
the body should not have other large bodies near its orbit;
the body does not have to be a star.

In turn, the polar star is a cosmic body that emits light and is a powerful source of energy. This is explained, firstly, by the thermonuclear reactions occurring in it, and secondly, by the processes of gravitational compression, as a result of which a huge amount of energy is released.

Planets of the solar system today

solar system- This is a planetary system that consists of a central star - the Sun - and all natural space objects revolving around it.

So, today the solar system consists of of the eight planets: four inner, so-called planets terrestrial group, and the four outer planets, called the gas giants.
The terrestrial planets include Earth, Mercury, Venus and Mars. All of them consist mainly of silicates and metals.

The outer planets are Jupiter, Saturn, Uranus and Neptune. The composition of gas giants consists mainly of hydrogen and helium.

The sizes of the planets in the solar system vary both within groups and between groups. So, the gas giants are much larger and more massive than the terrestrial planets.
Closest to the Sun is Mercury, then as far as the distance: Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

It would be wrong to consider the characteristics of the planets of the solar system without paying attention to its main component: the Sun itself. Therefore, we will start with it.

The sun planet is a star that gave rise to all life in the solar system. Planets, dwarf planets and their satellites, asteroids, comets, meteorites and cosmic dust revolve around it.

The sun arose about 5 billion years ago, is a spherical, hot plasma ball and has a mass that is more than 300 thousand times the mass of the Earth. The surface temperature is over 5,000 degrees Kelvin, and the core temperature is over 13 million K.

The Sun is one of the largest and brightest stars in our galaxy, which is called the Milky Way Galaxy. The Sun is located at a distance of about 26 thousand light years from the center of the Galaxy and makes a complete revolution around it in about 230-250 million years! For comparison, the Earth makes a complete revolution around the Sun in 1 year.

Mercury planet

Mercury is the smallest planet in the system and is closest to the Sun. Mercury has no satellites.

The surface of the planet is covered with craters that arose about 3.5 billion years ago as a result of massive bombardments by meteorites. The diameter of the craters can range from a few meters to more than 1000 km.

The atmosphere of Mercury is highly rarefied, consists mainly of helium and is blown by the solar wind. Since the planet is located very close to the Sun and does not have an atmosphere that would keep warm at night, the temperature on the surface ranges from -180 to +440 degrees Celsius.

By earthly standards, Mercury makes a complete revolution around the Sun in 88 days. On the other hand, a Mercury day is equal to 176 Earth days.

Venus planet

Venus is the second closest planet to the Sun in the solar system. Venus is only slightly smaller than Earth, which is why it is sometimes referred to as "Earth's sister". Has no satellites.

The atmosphere consists of carbon dioxide mixed with nitrogen and oxygen. The air pressure on the planet is more than 90 atmospheres, which is 35 times more than the earth.

Carbon dioxide and, as a result, the greenhouse effect, a dense atmosphere, as well as proximity to the Sun, allow Venus to carry the title of "hottest planet". The temperature on its surface can reach 460°C.

Venus is one of the brightest objects in the Earth's sky after the Sun and Moon.

Planet Earth

Earth is the only known planet in the universe today that has life on it. The earth has the large sizes, mass and density among the so-called inner planets solar system.

The age of the Earth is about 4.5 billion years, and life appeared on the planet about 3.5 billion years ago. The Moon is a natural satellite, the largest of the satellites of the terrestrial planets.

The atmosphere of the Earth is fundamentally different from the atmospheres of other planets due to the presence of life. Most of the atmosphere is nitrogen, but it also contains oxygen, argon, carbon dioxide and water vapor. Ozone layer and the Earth's magnetic field, in turn, weaken the life-threatening effects of solar and cosmic radiation.

Due to the carbon dioxide contained in the atmosphere, the greenhouse effect also takes place on Earth. It does not appear as strongly as on Venus, but without it, the air temperature would be approximately 40 ° C lower. Without the atmosphere, temperature fluctuations would be very significant: according to scientists, from -100 ° C at night to + 160 ° C during the day.

About 71% of the Earth's surface is occupied by the oceans, the remaining 29% are continents and islands.

mars planet

Mars is the seventh largest planet in the solar system. The "Red Planet", as it is also called due to the presence of a large amount of iron oxide in the soil. Mars has two moons: Deimos and Phobos.
The atmosphere of Mars is highly rarefied, and the distance to the Sun is almost one and a half times greater than that of the Earth. Therefore, the average annual temperature on the planet is -60 ° C, and temperature drops in some places reach 40 degrees during the day.

Distinctive features of the surface of Mars are impact craters and volcanoes, valleys and deserts, ice polar caps like those on Earth. On Mars is the most high mountain in the solar system: the extinct volcano Olympus, whose height is 27 km! As well as the largest canyon: the Marinera Valley, the depth of which reaches 11 km, and the length is 4500 km

Jupiter planet

Jupiter is the largest planet in the solar system. It is 318 times heavier than the Earth, and almost 2.5 times more massive than all the planets in our system combined. In its composition, Jupiter resembles the Sun - it consists mainly of helium and hydrogen - and radiates a huge amount of heat, equal to 4 * 1017 watts. However, in order to become a star like the Sun, Jupiter must be another 70-80 times heavier.

Jupiter has as many as 63 satellites, of which it makes sense to list only the largest ones - Callisto, Ganymede, Io and Europa. Ganymede is the largest moon in the solar system, larger than even Mercury.

Due to certain processes in the inner atmosphere of Jupiter, many vortex structures appear in its outer atmosphere, for example, stripes of clouds of brown-red shades, as well as the Great Red Spot, a giant storm known since the 17th century.

saturn planet

Saturn is the second largest planet in the solar system. Business card Saturn is, of course, its ring system, which consists mainly of ice particles different sizes(from tenths of a millimeter to several meters), as well as rocks and dust.

Saturn has 62 moons, the largest of which are Titan and Enceladus.
In its composition, Saturn resembles Jupiter, but in density it is inferior even to ordinary water.
The outer atmosphere of the planet looks calm and homogeneous, which is explained by a very dense layer of fog. However, the wind speed in some places can reach 1800 km/h.

Uranus planet

Uranus is the first planet to be discovered with a telescope, and also the only planet in the solar system that wraps around the sun, "lying on its side."
Uranus has 27 moons named after Shakespearean heroes. The largest of them are Oberon, Titania and Umbriel.

The composition of the planet differs from the gas giants in the presence of a large number of high-temperature modifications of ice. Therefore, along with Neptune, scientists have identified Uranus in the category of "ice giants". And if Venus has the title of "hottest planet" in the solar system, then Uranus is the coldest planet with a minimum temperature of about -224 ° C.

Neptune planet

Neptune is the most distant planet from the center of the solar system. The history of its discovery is interesting: before observing the planet through a telescope, scientists calculated its position in the sky using mathematical calculations. This happened after the discovery of inexplicable changes in the movement of Uranus in its own orbit.

To date, 13 satellites of Neptune are known to science. The largest of them - Triton - is the only satellite that moves in the opposite direction to the rotation of the planet. The fastest winds in the solar system also blow against the rotation of the planet: their speed reaches 2200 km/h.

The composition of Neptune is very similar to Uranus, therefore it is the second "ice giant". However, like Jupiter and Saturn, Neptune has an internal source of heat and radiates 2.5 times more energy than it receives from the Sun.
The planet's blue color comes from traces of methane in the outer atmosphere.

Conclusion
Pluto, unfortunately, did not have time to get into our parade of planets in the solar system. But it is absolutely not worth worrying about this, because all the planets remain in their places, despite changes in scientific views and concepts.

So, we answered the question of how many planets are there in the solar system. There are only 8 .

The solar system is a system of planets, which includes its center - the Sun, as well as other objects of the Cosmos. They revolve around the sun. More recently, 9 objects of the Cosmos that revolve around the Sun were called “planet”. Now scientists have established that beyond the boundaries of the solar system there are planets that revolve around stars.

In 2006, the Union of Astronomers declared that the planets of the solar system are spherical cosmic objects revolving around the sun. On the scale of the solar system, the Earth appears to be extremely small. In addition to the Earth, eight planets revolve around the Sun in their individual orbits. All of them are larger than the Earth. They rotate in the plane of the ecliptic.

Planets in the solar system: types

Location of the terrestrial group in relation to the Sun

The first planet is Mercury, followed by Venus; next comes our Earth and finally Mars.
The terrestrial planets do not have many satellites or moons. Of these four planets, only Earth and Mars have moons.

The planets that belong to the terrestrial group are highly dense, composed of metal or stone. Basically, they are small and rotate around their own axis. Their rotation speed is also low.

gas giants

These are four space objects that are on greatest distance from the Sun: at number 5 is Jupiter, followed by Saturn, then Uranus and Neptune.

Jupiter and Saturn are impressive planets, made up of compounds of hydrogen and helium. The density of gas planets is low. They rotate at high speed, have satellites and are surrounded by asteroid rings.
“Ice giants”, which include Uranus and Neptune, are smaller, their atmospheres contain methane, carbon monoxide.

Gas giants have a strong gravitational field, so they can attract many space objects, unlike the terrestrial group.

According to scientists, asteroid rings are the remains of moons altered by the gravitational field of the planets.

dwarf planet

Dwarfs are space objects, the size of which does not reach the planet, but exceeds the dimensions of the asteroid. There are many such objects in the solar system. They are concentrated in the Kuiper belt region. The satellites of the gas giants are dwarf planets that have left their orbit.

Planets of the solar system: the process of emergence

According to the hypothesis of cosmic nebulae, stars are born in clouds of dust and gas, in nebulae.
Due to the force of attraction, substances are combined. Under the influence of the concentrated force of gravity, the center of the nebula is compressed and stars are formed. Dust and gases are transformed into rings. The rings rotate under the influence of gravity, and planetasimals form in whirlpools, which increase and attract cosmetic objects to themselves.

Under the influence of the force of gravity, the planetazimals are compressed and acquire a spherical shape. Spheres can combine and gradually turn into protoplanets.



There are eight planets within the solar system. They revolve around the sun. Their location is:
The nearest “neighbor” of the Sun is Mercury, followed by Venus, then the Earth, then Mars and Jupiter, further from the Sun are Saturn, Uranus and the last one, Neptune.

Universe (space)- this is the whole world around us, boundless in time and space and infinitely diverse in the forms that eternally moving matter takes. The boundlessness of the Universe can be partly imagined on a clear night with billions of different sizes of luminous flickering points in the sky, representing distant worlds. Rays of light at a speed of 300,000 km / s from the most distant parts of the universe reach the Earth in about 10 billion years.

According to scientists, the universe was formed as a result of the "Big Bang" 17 billion years ago.

It consists of clusters of stars, planets, cosmic dust and other cosmic bodies. These bodies form systems: planets with satellites (for example, the solar system), galaxies, metagalaxies (clusters of galaxies).

Galaxy(Late Greek galaktikos- milky, milky, from Greek gala- milk) is an extensive star system that consists of many stars, star clusters and associations, gas and dust nebulae, as well as individual atoms and particles scattered in interstellar space.

There are many galaxies in the universe of various sizes and shapes.

All stars visible from Earth are part of the Milky Way galaxy. It got its name due to the fact that most of the stars can be seen on a clear night in the form of the Milky Way - a whitish blurry band.

In total, the Milky Way Galaxy contains about 100 billion stars.

Our galaxy is in constant rotation. Its speed in the universe is 1.5 million km/h. If you look at our galaxy from its north pole, then the rotation occurs clockwise. The sun and the stars closest to it make a complete revolution around the center of the galaxy in 200 million years. This period is considered galactic year.

Similar in size and shape to the Milky Way galaxy is the Andromeda Galaxy, or the Andromeda Nebula, which is located at a distance of about 2 million light years from our galaxy. Light year- the distance traveled by light in a year, approximately equal to 10 13 km (the speed of light is 300,000 km / s).

For clarity, the study of the movement and location of stars, planets and other celestial bodies the concept of the celestial sphere is used.

Rice. 1. The main lines of the celestial sphere

Celestial sphere is an imaginary sphere of arbitrarily large radius, in the center of which is the observer. Stars, the Sun, the Moon, planets are projected onto the celestial sphere.

The most important lines on the celestial sphere are: a plumb line, zenith, nadir, celestial equator, ecliptic, celestial meridian, etc. (Fig. 1).

plumb line- a straight line passing through the center of the celestial sphere and coinciding with the direction of the plumb line at the point of observation. For an observer on the surface of the Earth, a plumb line passes through the center of the Earth and the point of observation.

The plumb line intersects with the surface of the celestial sphere at two points - zenith, over the observer's head, and nadire - diametrically opposite point.

The great circle of the celestial sphere, the plane of which is perpendicular to the plumb line, is called mathematical horizon. It divides the surface of the celestial sphere into two halves: visible to the observer, with the apex at the zenith, and invisible, with the apex at the nadir.

The diameter around which the celestial sphere rotates is axis of the world. It intersects with the surface of the celestial sphere at two points - north pole of the world And south pole of the world. north pole called the one from which the rotation of the celestial sphere occurs clockwise, if you look at the sphere from the outside.

The great circle of the celestial sphere, whose plane is perpendicular to the axis of the world, is called celestial equator. It divides the surface of the celestial sphere into two hemispheres: northern, with a peak at the north celestial pole, and south, with a peak at the south celestial pole.

The great circle of the celestial sphere, the plane of which passes through the plumb line and the axis of the world, is the celestial meridian. It divides the surface of the celestial sphere into two hemispheres - eastern And western.

The line of intersection of the plane of the celestial meridian and the plane of the mathematical horizon - noon line.

Ecliptic(from Greek. ekieipsis- eclipse) big circle the celestial sphere, along which the apparent annual movement of the Sun occurs, more precisely, its center.

The plane of the ecliptic is inclined to the plane of the celestial equator at an angle of 23°26"21".

To make it easier to remember the location of the stars in the sky, people in antiquity came up with the idea of ​​combining the brightest of them into constellations.

Currently, 88 constellations are known that bear the names of mythical characters (Hercules, Pegasus, etc.), zodiac signs (Taurus, Pisces, Cancer, etc.), objects (Libra, Lyra, etc.) (Fig. 2).

Rice. 2. Summer-autumn constellations

Origin of galaxies. The solar system and its individual planets still remains an unsolved mystery of nature. There are several hypotheses. It is currently believed that our galaxy formed from a gas cloud composed of hydrogen. At the initial stage of the evolution of the galaxy, the first stars formed from the interstellar gas-dust medium, and 4.6 billion years ago, the solar system.

Composition of the solar system

The set of celestial bodies moving around the Sun as a central body forms solar system. It is located almost on the outskirts of the Milky Way galaxy. The solar system is involved in rotation around the center of the galaxy. The speed of its movement is about 220 km / s. This movement occurs in the direction of the constellation Cygnus.

The composition of the solar system can be represented in the form of a simplified diagram shown in fig. 3.

Over 99.9% of the mass of the matter of the solar system falls on the Sun and only 0.1% - on all its other elements.

Hypothesis of I. Kant (1775) - P. Laplace (1796)	Hypothesis of D. Jeans (early 20th century)	Hypothesis of Academician O.P. Schmidt (40s of XX century)	Hypothesis of a Calemic V. G. Fesenkov (30s of XX century)
The planets were formed from gas-dust matter (in the form of a hot nebula). Cooling is accompanied by compression and an increase in the speed of rotation of some axis. Rings appeared at the equator of the nebula. The substance of the rings collected in red-hot bodies and gradually cooled down.	A larger star once passed by the Sun, and gravity pulled out a jet of hot substance (a prominence) from the Sun. Condensations formed, from which later - planets	The gas-dust cloud revolving around the Sun should have taken a solid shape as a result of the collision of particles and their movement. Particles coalesced into clusters. The attraction of smaller particles by clumps should have contributed to the growth of the surrounding matter. The orbits of the clumps should have become almost circular and lying almost in the same plane. Condensations were the embryos of the planets, absorbing almost all the matter from the gaps between their orbits.	The Sun itself arose from a rotating cloud, and the planets from secondary condensations in this cloud. Further, the Sun greatly decreased and cooled to its present state.

Rice. 3. Composition of the solar systems

Sun

Sun is a star, a giant hot ball. Its diameter is 109 times the diameter of the Earth, its mass is 330,000 times the mass of the Earth, but average density small - only 1.4 times the density of water. The sun is located at a distance of about 26,000 light years from the center of our galaxy and revolves around it, making one revolution in about 225-250 million years. The orbital speed of the Sun is 217 km/s, so it travels one light year in 1400 Earth years.

Rice. 4. The chemical composition of the Sun

The pressure on the Sun is 200 billion times higher than at the surface of the Earth. The density of solar matter and pressure rapidly increase in depth; the increase in pressure is explained by the weight of all overlying layers. The temperature on the surface of the Sun is 6000 K, and inside it is 13,500,000 K. The characteristic lifetime of a star like the Sun is 10 billion years.

Table 1. General information about the sun

The chemical composition of the Sun is about the same as that of most other stars: about 75% is hydrogen, 25% is helium, and less than 1% is all other chemical elements(carbon, oxygen, nitrogen, etc.) (Fig. 4).

The central part of the Sun with a radius of approximately 150,000 km is called solar core. This is a nuclear reaction zone. The density of matter here is about 150 times higher than the density of water. The temperature exceeds 10 million K (on the Kelvin scale, in terms of degrees Celsius 1 ° C \u003d K - 273.1) (Fig. 5).

Above the core, at distances of about 0.2-0.7 of the radius of the Sun from its center, there is radiant energy transfer zone. Energy transfer here is carried out by absorption and emission of photons separate layers particles (see Fig. 5).

Rice. 5. Structure of the Sun

Photon(from Greek. phos- light), an elementary particle that can exist only by moving at the speed of light.

Closer to the surface of the Sun, vortex mixing of the plasma occurs, and the energy transfer to the surface occurs

predominantly by the movements of the substance itself. This type of energy transfer is called convection and the layer of the Sun, where it occurs, - convective zone. The thickness of this layer is approximately 200,000 km.

Above the convective zone is the solar atmosphere, which is constantly fluctuating. Both vertical and horizontal waves with lengths of several thousand kilometers propagate here. The oscillations occur with a period of about five minutes.

The inner layer of the sun's atmosphere is called photosphere. It consists of light bubbles. This granules. Their dimensions are small - 1000-2000 km, and the distance between them is 300-600 km. About a million granules can be simultaneously observed on the Sun, each of which exists for several minutes. The granules are surrounded by dark spaces. If the substance rises in the granules, then around them it falls. The granules create a general background against which one can observe such large-scale formations as torches, sunspots, prominences, etc.

sunspots- dark areas on the Sun, the temperature of which is lowered compared to the surrounding space.

solar torches called the bright fields surrounding sunspots.

prominences(from lat. protubero- I swell) - dense condensations of relatively cold (compared to the ambient temperature) matter that rise and are held above the surface of the Sun by a magnetic field. To the emergence magnetic field The sun can be driven by the fact that different layers of the sun rotate at different speeds: the inner parts rotate faster; the core rotates especially fast.

Prominences, sunspots, and flares are not the only examples of solar activity. It also includes magnetic storms and explosions that call flashes.

Above the photosphere is chromosphere is the outer shell of the sun. The origin of the name of this part of the solar atmosphere is associated with its reddish color. The thickness of the chromosphere is 10-15 thousand km, and the density of matter is hundreds of thousands of times less than in the photosphere. The temperature in the chromosphere is growing rapidly, reaching tens of thousands of degrees in its upper layers. At the edge of the chromosphere are observed spicules, which are elongated columns of compacted luminous gas. The temperature of these jets is higher than the temperature of the photosphere. Spicules first rise from the lower chromosphere by 5000-10000 km, and then fall back, where they fade. All this happens at a speed of about 20,000 m/s. Spikula lives 5-10 minutes. The number of spicules existing on the Sun at the same time is about a million (Fig. 6).

Rice. 6. The structure of the outer layers of the Sun

The chromosphere surrounds solar corona is the outer layer of the sun's atmosphere.

The total amount of energy radiated by the Sun is 3.86. 1026 W, and only one two billionth of this energy is received by the Earth.

Solar radiation includes corpuscular And electromagnetic radiation.Corpuscular fundamental radiation- this is a plasma stream, which consists of protons and neutrons, or in other words - sunny wind, which reaches near-Earth space and flows around the entire Earth's magnetosphere. electromagnetic radiation is the radiant energy of the sun. It reaches the earth's surface in the form of direct and scattered radiation and provides a thermal regime on our planet.

In the middle of the XIX century. Swiss astronomer Rudolf Wolf(1816-1893) (Fig. 7) calculated a quantitative indicator of solar activity, known throughout the world as the Wolf number. Having processed the data on observations of sunspots accumulated by the middle of the last century, Wolf was able to establish the average 1-year cycle of solar activity. In fact, the time intervals between years of maximum or minimum Wolf numbers range from 7 to 17 years. Simultaneously with the 11-year cycle, a secular, more precisely 80-90-year cycle of solar activity takes place. Inconsistently superimposed on each other, they make noticeable changes in the processes taking place in the geographic envelope of the Earth.

A. L. Chizhevsky (1897-1964) (Fig. 8) pointed out the close connection of many terrestrial phenomena with solar activity back in 1936, who wrote that the vast majority of physical and chemical processes on Earth are the result of the impact space forces. He was also one of the founders of such a science as heliobiology(from Greek. helios- the sun), studying the influence of the Sun on the living substance of the geographic shell of the Earth.

Depending on solar activity, such physical phenomena occur on Earth, such as: magnetic storms, the frequency of auroras, the amount of ultraviolet radiation, the intensity of thunderstorm activity, air temperature, atmospheric pressure, precipitation, the level of lakes, rivers, ground water, salinity and efficiency of the seas, etc.

The life of plants and animals is associated with the periodic activity of the Sun (there is a correlation between the solar cycle and the period of the growing season in plants, the reproduction and migration of birds, rodents, etc.), as well as humans (diseases).

At present, the relationship between solar and terrestrial processes continues to be studied with the help of artificial Earth satellites.

terrestrial planets

In addition to the Sun, planets are distinguished in the Solar System (Fig. 9).

By size, geographical indicators and chemical composition, the planets are divided into two groups: terrestrial planets And giant planets. The terrestrial planets include, and. They will be discussed in this subsection.

Rice. 9. Planets of the solar system

Earth is the third planet from the Sun. A separate section will be devoted to it.

Let's summarize. The density of the matter of the planet depends on the location of the planet in the solar system, and, taking into account its size, the mass. How
The closer the planet is to the Sun, the higher its average density of matter. For example, for Mercury it is 5.42 g/cm2, Venus - 5.25, Earth - 5.25, Mars - 3.97 g/cm 3 .

The general characteristics of the terrestrial planets (Mercury, Venus, Earth, Mars) are primarily: 1) comparatively small size; 2) high temperatures on the surface and 3) the high density of the matter of the planets. These planets rotate relatively slowly on their axis and have few or no satellites. In the structure of the planets of the terrestrial group, four main shells are distinguished: 1) a dense core; 2) the mantle covering it; 3) bark; 4) light gas-water shell (excluding Mercury). Traces of tectonic activity have been found on the surface of these planets.

giant planets

Now let's get acquainted with the giant planets, which are also included in our solar system. This , .

Giant planets have the following general characteristics: 1) large size and mass; 2) quickly rotate around an axis; 3) have rings, many satellites; 4) the atmosphere consists mainly of hydrogen and helium; 5) have a hot core of metals and silicates in the center.

They are also different: 1) low temperatures on a surface; 2) low density of matter of the planets.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

2. What planets are part of the solar system?

The terrestrial planets (Mercury, Venus, Earth and Mars) and the giant planets (Jupiter, Saturn, Uranus and Neptune).

3. Complete the sentences regarding the general characteristics of the planets of the solar system

Option 1.

• The planet with the largest semi-axis of the orbit -Neptune.
• Which of the giant planets is closest to Earth?Jupiter.
• Which terrestrial planet has the longest orbital period around the sun?Mars.
• The largest planet isJupiter.
• The largest mass of the planets of the terrestrial group hasEarth.
• Which planet has the smallest mass?Mercury.
• Which planet has the most average density:Saturn.
• The planet with the longest period of rotation around its axis -Venus.
• Planet with one moonEarth.
• The solar system contains the following giant planets:Jupiter, Saturn, Uranus and Neptune.

Option 2.

• Which planet orbits closest to the Sun?Mercury.
• The closest planet to Earth isVenus.
• The giant planet with the shortest orbital period around the SunJupiter.
• Which terrestrial planet is the largest in size:Earth.
• The planet with the largest mass isJupiter.
• The planet whose mass is closest to the mass of the Earth isVenus.
• The planet with the highest average density isEarth.
• The planet that rotates the fastest on its axisJupiter.
• Planets that do not have a satellite:Mercury and Venus.
• Terrestrial planets:Mercury, Venus, Earth and Mars.

4. Complete the sentences concerning the main properties of the bodies of the solar system

The bulk of the solar system is concentrated in Sun.

The shape of the orbits of the planets almost circular.

The planes of the orbits of the planets almost coincide with the plane of the ecliptic.

Most planets rotate around their axes in the same direction, with the exception of Venus and Uranus.

What groups are the planets divided by their physical and dynamic properties: terrestrial planets and giant planets.

5. In a number of numbers expressing the average distances of the planets from the Sun, some regularity is observed. Calculate the values ​​of the semi-major axes of the orbits of the planets using the Titius-Bode formula and draw a conclusion

Planet	exponent n	Calculated distance, a.u.	True distance, a.u.
Mercury	-∞	0,4	0,39
Venus	0	0,7	,72
Earth	1	1	1
Mars	2	1,6	1,52
asteroid belt	3	2,8	2,9
Jupiter	4	5,2	5,2
Saturn	5	10	9,54
Uranus	6	19,6	19,19
neputn	7	38,8	30,07

Conclusions: The rule of planetary distances is well suited to the true distances of the planets from the Sun up to Uranus (with an error for Saturn and Uranus of 0.5 AU. The orbit of Neptune does not fit into the rule.

The science

We all know from childhood that at the center of our solar system is the Sun, around which the four nearest planets of the terrestrial group, including Mercury, Venus, Earth and Mars. They are followed by four gas giant planets: Jupiter, Saturn, Uranus and Neptune.

After Pluto ceased to be considered a planet in the solar system in 2006, and moved into the category of dwarf planets, the number of major planets has been reduced to 8.

Although many people know the general structure, there are many myths and misconceptions regarding the solar system.

Here are 10 facts you may not have known about the solar system.

1. The hottest planet is not closest to the Sun

Many people know that Mercury is the closest planet to the Sun, whose distance is almost two times less than the distance from the Earth to the Sun. It's no surprise that many people believe that Mercury is the hottest planet.

In fact Venus is the hottest planet in the solar system- the second planet close to the Sun, where the average temperature reaches 475 degrees Celsius. This is enough to melt tin and lead. At the same time, the maximum temperature on Mercury is about 426 degrees Celsius.

But due to the absence of an atmosphere, the surface temperature of Mercury can vary by hundreds of degrees, while carbon dioxide on the surface of Venus maintains a virtually constant temperature at any time of the day or night.

2. The boundary of the solar system is a thousand times farther from Pluto

We tend to think that the solar system extends to the orbit of Pluto. Today, Pluto is not even considered a major planet, but this idea has remained in the minds of many people.

Scientists have discovered many objects orbiting the Sun, which are much further than Pluto. These are the so-called trans-Neptunian or Kuiper belt objects. The Kuiper belt extends for 50-60 astronomical units (the astronomical unit or the average distance from the Earth to the Sun is 149,597,870,700 m).

3. Almost everything on planet Earth is a rare element

The earth is mainly made up of iron, oxygen, silicon, magnesium, sulfur, nickel, calcium, sodium and aluminum.

Although all of these elements have been found in different places throughout the universe, they are only trace elements that overshadow the abundance of hydrogen and helium. Thus, the Earth for the most part consists of rare elements. This does not speak of any special place planet Earth, since the cloud from which the Earth formed contained a large amount of hydrogen and helium. But since they are light gases, they were blown into space by the heat of the sun as the Earth formed.

4. The solar system has lost at least two planets

Pluto was originally considered a planet, but due to its very small size (much smaller than our moon), it was renamed a dwarf planet. Astronomers also once believed that there is a planet Vulcan, which is closer to the Sun than Mercury. Its possible existence was discussed 150 years ago to explain some of the features of Mercury's orbit. However, later observations ruled out the possibility of Vulcan's existence.

Besides, latest research showed what was possible there was a fifth giant planet, similar to Jupiter, which revolved around the Sun, but was ejected from the solar system due to gravitational interaction with other planets.

5. Jupiter has the largest ocean of all the planets

Jupiter, which orbits in cold space, five times farther from the Sun than the planet Earth, was able to hold much more high level hydrogen and helium during formation than our planet.

One might even say that Jupiter is mostly made up of hydrogen and helium. Considering the mass of the planet and chemical composition, as well as the laws of physics, under cold clouds, an increase in pressure should lead to the transition of hydrogen to a liquid state. That is, on Jupiter there should be deepest ocean liquid hydrogen.

According to computer models on this planet, not only is the largest ocean in the solar system, its depth is approximately 40,000 km, that is, it is equal to the circumference of the Earth.

6. Even the smallest bodies in the solar system have satellites

It was once believed that only such large objects as planets could have natural satellites or moons. The fact that satellites exist is sometimes even used to determine what a planet really is. It seems counterintuitive that small cosmic bodies could have enough gravity to hold a satellite. After all, Mercury and Venus don't have them, and Mars only has two tiny moons.

But in 1993, the Galileo interplanetary station discovered the Dactyl satellite, just 1.6 km wide, near the asteroid Ida. Has since been found moons orbiting about 200 other minor planets, which greatly complicated the definition of "planet".

7. We live inside the sun

We usually think of the Sun as a huge hot ball of light located at a distance of 149.6 million km from the Earth. In fact the outer atmosphere of the sun extends much further than the visible surface.

Our planet is orbiting within its rarefied atmosphere, and we can see it when the gusts solar wind cause the appearance of the aurora. In this sense, we live inside the Sun. But the solar atmosphere doesn't end on Earth. Auroras can be observed on Jupiter, Saturn, Uranus and even distant Neptune. The farthest region of the solar atmosphere is the heliosphere extends at least 100 astronomical units. This is about 16 billion kilometers. But since the atmosphere is shaped like a drop due to the movement of the Sun in space, its tail can reach from tens to hundreds of billions of kilometers.

8. Saturn isn't the only planet with rings.

While Saturn's rings are by far the most beautiful and easy to observe, Jupiter, Uranus and Neptune also have rings. While the bright rings of Saturn are made up of icy particles, the very dark rings of Jupiter are mostly dust particles. They may contain minor fragments of decayed meteorites and asteroids, and possibly particles of the volcanic moon Io.

The ring system of Uranus is slightly more visible than that of Jupiter, and may have formed after the collision of small satellites. Neptune's rings are faint and dark, like those of Jupiter. The dim rings of Jupiter, Uranus and Neptune impossible to see through small telescopes from Earth, because Saturn became best known for its rings.

Contrary to popular belief, there is a body in the solar system with an atmosphere essentially similar to that of Earth. This is Saturn's moon Titan.. It is larger than our Moon and is close in size to the planet Mercury. Unlike the atmospheres of Venus and Mars, which are much thicker and thinner, respectively, than those of Earth and are composed of carbon dioxide, Titan's atmosphere is mostly nitrogen.

The Earth's atmosphere is approximately 78 percent nitrogen. The similarity to the Earth's atmosphere, and especially the presence of methane and other organic molecules, has led scientists to believe that Titan can be considered an analogue of the early Earth, or there is some kind of biological activity. For this reason, Titan is considered the best place in the solar system to search for signs of life.