The sun has a large force of attraction, due to which it holds planets forming a whole system near it. Scientists are constantly studying the solar system and constantly make incredible discoveries that help to better understand the structure of space.
What is the solar system?
The solar system is a collection of planets orbiting a central star. Scientists were able to establish that she was approximately 4.57 billion years old, and she appeared due to the gravitational compression of a gas-dust cloud.
The system is based on a bright star - the Sun, which holds planets and other objects. causing them to orbit at a certain distance. It is many times larger in diameter than other objects located in the region of its attraction.
Interesting fact: The sun has such a large mass that all other planets of the system make up only 0.0014% of its weight.
In addition to the star, the Solar System contains eight major planets, as well as five dwarf planets. It is located in the Milky Way galaxy, in the sleeve of Orion.
Occurrence
Since the solar system is billions of years old, people can only hypothesize how it appears. The most popular is the nebular theory put forward by scientists Laplace, Kant and Swedenborg in the 18th century. It is based on the fact that the system was formed due to the gravitational collapse of one of the parts of a huge cloud consisting of gas and dust. In the future, the hypothesis was supplemented by data obtained in space exploration.
Now the process of the emergence of the solar system is described by the following steps:
- Initially, in this area of the universe there was a cloud consisting of helium, hydrogen and other substances obtained during the explosions of old stars. In a small part of it, compaction began, which became the center of gravitational collapse. He gradually began to attract surrounding substances.
- Due to the attraction of substances, the size of the cloud began to decrease, while the rotation speed increased. Gradually, his form turned into a disk.
- As the compression increased, the density of particles per unit volume increased, which led to a gradual heating of the substance due to frequent collisions of molecules.
- When the center of gravity collapse warmed up to several thousand Kelvin, it began to glow, which meant the formation of a protostar. In parallel with this, other seals began to appear in different areas of the disk, which in the future will serve as gravitational centers for planet formation.
- The final stage of the formation of the solar system began at a time when the temperature of the center of the protostar exceeded several million Kelvin. Then helium and hydrogen entered into a fusion reaction, which led to the appearance of a full-fledged star. The remaining disk seals gradually formed into planets that began to rotate in the same direction around the Sun, being on the same plane.
This process lasted a very long time, and scientists can only guess how many years it took to form the solar system.
The structure of the solar system
At the center of the system is the Sun, consisting of helium and hydrogen. The temperature on its surface is about 6000 degrees Celsius, and the size of the sphere is many times larger than other objects located in the region of its attraction. The star belongs to the yellow dwarf.
Interesting fact: The sun attracts objects at a distance of two light years. This is approximately 18.9 trillion kilometers.
Around the luminary at different distances are planets that are divided by scientists into two groups: earthly and gas.
Earth group planets
The Earth group is closer to the Sun. Its planets have a rocky structure and high density, which is why their size is smaller than that of gas giants.
Mercury
The planet closest to the Sun is also the smallest in the system. Its radius is only 2440 km. It received its name in honor of the god of trade Mercury. Its surface is gray, which is why many compare with the moon. The planet does not contain satellites, and due to strong solar winds, its atmosphere is almost completely discharged.
Venus
The second planet from the Sun, bears a name in honor of the ancient Roman goddess of love. Distinctive features are the absence of natural satellites and a high carbon dioxide content in the atmosphere. The radius of Venus practically coincides with the earth: 6051 km, which is only 5% less. Because of this, the planets are called “sisters.” However, outwardly Venus is very different, representing a ball of milky color. The surface consists almost entirely of frozen lava with rare meteorite craters.
Land
The third planet from the Sun, the only one where there are large territorial areas filled with water. Due to favorable climatic conditions and sufficient resources, it is the only source of life in the solar system. The radius of the planet is 6378 km.
Mars
The “red” planet is the farthest from the Sun, belonging to the earth group. It is also considered the smallest after Mercury. Its radius is 3396 km. The surface consists mainly of sandy and earthen reliefs, divided into light and dark areas, referred to as continents and seas, respectively. In the 21st century, Mars is of great interest to scientists. Since the planet is in relative reach, rovers are regularly sent to it to collect data.
Gas group planets
This group consists of four gas giants located at a greater distance from the Sun than other planets. The huge size is due to the low density and a large number of gaseous substances in the composition.
Jupiter
The largest planet in the solar system. Its radius is 69912 km, which is almost 20 times higher than the earth. Scientists can not yet accurately determine the composition of the planet, it is only known that it has more xenon, argon and krypton more than on the Sun. Jupiter also has 67 satellites, some of which are quite similar in size to planets. For example, Ganymede is 8% larger than Mercury, and Io has its own atmosphere. There is also a theory that Jupiter should have become a full-fledged star, but at the stage of development, it remained a planet.
Saturn
The sixth planet, famous for its rings, consisting of ice and rocky meteoroids. The radius of Saturn is 57360 km. Scientists have not yet studied in detail the composition of the surface, but were able to establish that it contains almost the same chemical elements as on the Sun. There are 62 satellites around Saturn.
Interesting fact: Not so long ago it was found that in addition to Saturn, other gas giants also possess rings, but they are not so noticeable. So far, one can only guess about the reasons for their appearance.
Uranus
The third largest planet in the solar system. Its radius is 25267 km. The temperature on Uranus is kept at -230 degrees Celsius, which makes it the coldest planet. It also has a unique feature: the axis of rotation is located at an angle, which is why when moving the planet gives the impression of a rolling ball. The surface consists mainly of ice, and there is also a small amount of helium and hydrogen.
Neptune
The eighth planet from the Sun was discovered not by observation, but by mathematical calculations. Observing anomalies in the movement of Uranus, scientists have suggested that they arose due to the presence of another large celestial body. Neptune has a radius of 24,547 km. The surface is similar to uranium, but the strongest winds in the system, accelerating to 260 m / s, walk on it.
Orbit Sequence
Each planet has a specific orbit in which it revolves around the sun.The time that she spends to return to the same point, having completed a full circle, is called the year, most often it is measured in earth days.
- Mercury is closest to the Sun, due to which it rotates around it in the smallest orbit, and the year on it lasts 88 days;
- Venus makes a complete revolution around the star in 224 days;
- for the Earth, the year lasts 365 days;
- Mars makes a complete revolution almost twice as long as the third planet: in 687 days;
- Jupiter, the closest gaseous giant to the Sun, has a year duration of 4332 days;
- Saturn makes a full revolution in 10759 days - it is almost 30 Earth years;
- Being practically the most distant planet from the Sun, Uranus passes around a circle in 30685 days;
- Neptune has the largest orbit, and it has to travel the largest distance during its year, which lasts 60,190 days - almost 165 years.
Each planet also rotates around its axis at a certain speed, which is why the length of the day is different for them.
Pluto is part of the solar system or not?
Since the 19th century, scientists have suggested that the ninth planet exists in the solar system, located farthest from the sun. In the 1930s, 23-year-old Clyde Tombo, an employee of the Mount Wilson Observatory, managed to discover Pluto. He did this by regularly photographing the starry sky and searching for moving elements. The object was discovered in the Kuiper belt.
In the same year, Pluto was officially declared the ninth planet. Due to a lack of data, it was correlated in size with the Earth. But further studies have shown that it has a radius of only 2376 km, and its mass is 6 times less than that of the moon.
Interesting fact: Pluto’s area is only 0.6 million sq. km less than that of Russia and equal to 17.1 million sq. km.
The surface of the planet consists mainly of stone and ice, like most bodies from the Kuiper belt. Around Pluto are five satellites. The orbit of rotation around the Sun is oval, and at the maximum approximation, the planet is closer to the star than Neptune, and at the maximum distance, the distance is 7.4 billion km.
In further studies of the Kuiper belt, scientists discovered several more small planets, the size of which does not differ much from Pluto. In 2006, it was decided to rank them dwarf status. Since then, Pluto has officially ceased to be the ninth planet of the solar system. However, some scientists still insist that it should be moved back from dwarf to main.
Other objects
In addition to the Sun and planets, other objects are present in the system. These include:
- dwarf planets, inferior in size to the main ones;
- Kuiper belt - a disk-shaped area where there are many ice bodies, located beyond the orbit of Neptune;
- Oort cloud - accumulation of ice conglomerates;
- comets - the formation of gas, dust and ice, moving in space;
- asteroids - stone formations moving between Mars and Jupiter;
- meteorites - small solid objects that fall to the Earth, at the moment they enter the atmosphere they turn into meteors and burn up before reaching the surface of the planet.
Asteroids and comets from neighboring galaxies can periodically fly into the solar system, but this phenomenon is quite rare.
Oort Cloud Beyond the Solar System
The Oort cloud is located around the solar system and the Kuiper belt. Its internal borders begin at a distance of 2000 to 5000 AU from the Sun, and the outer ones lie in the range of 100,000-200,000 AU For ease of study, scientists divide the area into external and internal parts.
The cloud consists of trillions of bodies, consisting of ethane, water, methane, ammonia, hydrogen and other substances. Also among them are stone asteroids, which make up 2% of the total number of objects. The size of almost all bodies does not exceed a kilometer in diameter, dwarf planets are a rare exception.
Interplanetary space
Many people think that there is nothing between the planets. However, this assumption is incorrect. The sun continuously emits charged particles that propagate in space at a speed of 1.5 million km / h and form the heliosphere. Such a stream is called the solar wind. If an object does not have its own magnetic field that can hold the atmosphere, charged particles will literally tear it off. Such a fate befell Mars and Venus.
Colonization
In the XX century, people began to actively explore space, not only observing it from telescopes, but also launching various satellites, shuttles, rockets, etc. Scientists are also searching for life-friendly planets. Unfortunately, a cataclysm can occur at any moment on Earth, because of which humanity will have to look for a new home. Therefore, the possible colonization of space is not an empty phrase for modern observatories.
Back in the last century, probes were sent to various planets, still transmitting information about their journey. This helps to better learn about the structure and features of the objects of the solar system.
As for direct colonization, in the 21st century it is already in the order of things to send moon rovers and rovers that walk on the surfaces of the Earth’s satellite and the fourth planet in search of life and other unusual finds. However, now mankind is still on the verge of space travel, so there is no reason to talk about a potential relocation to another planet. Moreover, most of the large bodies of the solar system are not suitable for life.
Why the solar system is stable
All planets revolve around the Sun in their own orbits, without any contact with each other. Also, they are constantly acting on the attraction of a star, based on the law of universal gravitation. And since there is no frictional force in space, planets move at a constant speed, and enviable stability has been operating in the solar system for billions of years.
Earth location
The position of the Earth in the solar system can be called the most profitable, because it was on this planet that life was born. The third planet revolves around the star in an ellipsoid. The maximum distance between the Earth and the Sun is 152 million km and is called aphelion, and the minimum is 147 million km and is called perigee.
Interesting fact: during the journey, the Earth reaches aphelion in June, and perigee in January. It is at the intersection of these points that a stable cooling or warming begins on the planet.
Due to its favorable location, the Earth is constantly heated by the sun. Depending on the season and location, the surface temperature varies from -89 to 57 degrees Celsius. This is enough for the emergence and development of life.
The place of the solar system in the galaxy
In the Middle Ages, people thought that the Earth was the center of the universe. Since then it was impossible to appreciate the vastness of space, such an assumption seemed the most logical. It was later established that the planet is only part of the solar system, where a giant star is located in the middle. And even later it became known that it is only part of a large galaxy - the Milky Way, which, in turn, is one of many in the universe.
Scientists have compiled a global Milky Way. It covers all known borders, and the total length is approximately 100,000 light years. For convenience, the galaxy is depicted as a flattened disk. The solar system is located almost to the side, located at a distance of 28,000 light years from the center.
Solar System Study
Since the mid-20th century, people have been making active attempts to study the planets of the solar system. In 1957, the USSR launched Sputnik-1 into Earth orbit. He spent several months in space collecting data about the planet.
Over the next two decades, until the 80s, people sent Voyagers to most of the planets of the system, who took many pictures close up. This helped to compile detailed descriptions of objects and study the composition.
Now, scientists daily receive a lot of information about the planets of the solar system, sent by dozens of satellites.
Why do planetary orbits lie in the same plane?
In the solar system, stars and planets are on the same plane. Only a few orbits pass at a slight slope. Scientists believe that this is due to the formation of objects at one time and from one substance.
During the galactic collapse, when the solar system was born, the gaseous cloud gradually narrowed and turned into a rotating disk. Accordingly, when future planets began to turn into seals, they were already on the same plane.
The movement of the planets around the sun
The ancient Greek astronomer Ptolemy was the first to suggest that the planets and the Sun do not stand still, but rotate in orbits. However, due to a lack of technology and knowledge, the scientist believed that all objects move around the Earth.
The hypothesis that the movement of planets occurs around the Sun was put forward by Nikolai Copernicus. He built his own model of the solar system and wrote on its basis the work “On the Rotation of the Celestial Spheres”. The work was published in 1543 in Nuremberg. After some time, Kepler proved that the orbit of the planets is not round, but ellipsoidal. In 1687, Newton discovered the law of gravity, which explained the interaction of planets and the sun.
Interesting fact: Newton's law helped prove that the tides on Earth are due to lunar activity.
Now people have enough knowledge and technology to predict the exact trajectory of any planet. It is on the basis of these data that rockets and satellites are launched, which must meet the object at a certain point in space and after a fixed time.
