The Earth is a satellite of the Sun in cosmic space, forever circling around this source of heat and light, which makes life on Earth possible. The brightest celestial objects we constantly observe, besides the Sun and Moon, are our neighboring planets. They belong to those nine worlds (including the Earth) that revolve around the Sun (and its radius is 700 thousand km, i.e. 100 times the radius of the Earth) at distances reaching several billion kilometers. A group of planets together with the Sun makes up the Solar System. Although the planets appear similar to stars, they are actually much smaller and darker. They are visible only because they reflect sunlight, which appears very bright because planets are much closer to Earth than stars. But if we moved our most powerful telescopes to the nearest star, then even with their help we would not be able to see these satellites of the Sun.
In addition to the planets, the solar “family” includes satellites of the planets (including our satellite, the Moon), asteroids, comets, meteoroids, and the solar wind. The planets are arranged in the following order: Mercury, Venus, Earth (one satellite - the Moon), Mars (two satellites - Phobos and Deimos), Jupiter (15 satellites), Saturn (16 satellites), Uranus (5 satellites), Neptune (2 satellites ) and Pluto (one satellite). The Earth is forty times closer to the Sun than Pluto and two and a half times farther than Mercury. It is possible that there are one or more planets beyond Pluto, but searching for them among the many stars weaker than 15th magnitude is too painstaking and does not justify the time spent on them. Perhaps they will be discovered “at the tip of the pen,” as has already been the case with Uranus, Neptune and Pluto. There should be planets around many other stars, but there is no direct observational data about them, and there are only some indirect indications.
Since 1962, planets and their satellites have been successfully studied by spacecraft. The atmospheres and surface of Venus and Mars were studied, the surface of Mercury, the cloud cover of Venus, Jupiter, Saturn, and the entire surface of the Moon were photographed, images of the satellites of Mars, Jupiter, Saturn, and the rings of Saturn and Jupiter were obtained. The descending spacecraft examined the physical and chemical properties of the rocks that make up the surface of Mars, Venus, and the Moon (samples of lunar rocks were delivered to Earth and carefully studied).
According to their physical characteristics, planets are divided into two groups: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn, Uranus, Neptune). Little is known about Pluto, but it appears to be closer in structure to the terrestrial planets.
On October 4, 1957, the world's first artificial Earth satellite was launched into low-Earth orbit. Thus began the space age in human history. Since then, artificial satellites have been regularly helping to study the cosmic bodies of our galaxy.
Artificial Earth satellites (AES)
In 1957, the USSR was the first to launch a satellite into low-Earth orbit. The United States was the second to do this, a year later. Later, many countries launched their satellites into Earth orbit - however, satellites purchased from the USSR, USA or China were often used for this. Nowadays satellites are launched even by radio amateurs. However, many satellites have important tasks: astronomical satellites explore the galaxy and space objects, biosatellites help conduct scientific experiments on living organisms in space, meteorological satellites help predict the weather and observe the Earth's climate, and the tasks of navigation and communication satellites are clear from their names. Satellites can be in orbit from several hours to several years: for example, manned spacecraft can become a short-term artificial satellite, and a space station can become a long-term spacecraft in Earth orbit. In total, more than 5,800 satellites have been launched since 1957, 3,100 of them are still in space, but of these three thousand, only about one thousand are operational.
Artificial lunar satellites (ALS)
At one time, ISLs were very helpful in studying the Moon: when entering its orbit, satellites photographed the lunar surface in high resolution and sent pictures to Earth. In addition, by changing the trajectory of the satellites, it was possible to draw conclusions about the gravitational field of the Moon, the features of its shape and internal structure. Here the Soviet Union was again ahead of everyone: in 1966, the Soviet automatic station Luna-10 was the first to enter lunar orbit. And over the next three years, 5 more Soviet satellites of the Luna series and 5 American satellites of the Lunar Orbiter series were launched.
Artificial satellites of the Sun
It is curious that until the 1970s, artificial satellites appeared near the Sun... by mistake. The first such satellite was Luna 1, which missed the Moon and entered the orbit of the Sun. And this despite the fact that switching to a heliocentric orbit is not so easy: the device must reach the second cosmic speed without exceeding the third. And when approaching planets, the device can slow down and become a satellite of the planet, or speed up and completely leave the solar system. But NASA satellites orbiting the Sun near the Earth's orbit began to perform detailed measurements of solar wind parameters. The Japanese satellite observed the Sun in the X-ray range for about ten years - until 2001. Russia launched a solar satellite in 2009: Coronas-Photon will study the most dynamic solar processes and monitor solar activity around the clock to predict geomagnetic disturbances.
Artificial satellites of Mars (ISM)
The first artificial satellites of Mars were... three ISMs at once. Two space probes were launched by the USSR (“Mars-2” and “Mars-3”) and another by the USA (“Mariner-9”). But the point is not that the launch was a “race” and there was such an overlap: each of these satellites had its own task. All three ISMs were launched into significantly different elliptical orbits and performed different scientific research, complementing each other. Mariner 9 produced a map of the surface of Mars for mapping, and Soviet satellites studied the characteristics of the planet: the flow of solar wind around Mars, the ionosphere and atmosphere, topography, temperature distribution, the amount of water vapor in the atmosphere and other data. In addition, Mars 3 was the first in the world to make a soft landing on the surface of Mars.
Artificial Satellites of Venus (ASV)
The first WIS were again Soviet spacecraft. Venera 9 and Venera 10 entered orbit in 1975. Having reached the planet. They were divided into satellites and devices lowered to the planet. Thanks to WIS radar, scientists were able to obtain radio images with a high degree of detail, and the devices that softly descended to the surface of Venus took the world's first photographs of the surface of another planet... The third satellite was the American Pioneer Venera 1 - it was launched three years later.
The Earth is a satellite of the Sun in cosmic space, forever circling around this source of heat and light, which makes life on Earth possible. There are other satellites circling around the Sun - the planets of the Solar System; each of them receives more or less solar heat and light, depending on its distance from the Sun, and they are located in the following order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. We are forty times closer to the Sun than Pluto, and 2½ times farther than Mercury. Almost every book on astronomy contains a description of a visual model of the solar system, where the Sun and planets are depicted as different fruits of various sizes, and the orbits, i.e., the paths of the planets around the central luminary, are depicted as circles of different sizes. There is no need to describe such a whole model again. Its main purpose is to show the comparative sizes of the planets and the Sun and to help imagine the enormity of the distances between the planets in comparison with their sizes. Let us limit ourselves to reminding that if 149 600000 km, representing (rounded) the distance of the Earth from the Sun, and making up astronomical unit distances, depicted in our model with a length of one meter, then the Sun will be depicted as a cherry, the Earth will be depicted as a speck of dust, less than a tenth of a millimeter, the largest of the planets, Jupiter, as a pinhead, and the smallest of the planets, Mercury and Pluto, as specks of dust, two to three times smaller in diameter, than a speck of dust model of the Earth. They won't even be visible to the eye. In addition to the main members of the solar system listed above, the solar family includes the satellites of the planets, including the Moon, which accompanies the globe and kindly illuminates it at night. It also includes many small planets - asteroids, small and large comets, which will be discussed later. But even smaller than asteroids are meteorites. These are stones of all possible sizes, mostly small, floating in outer space. Every year some of them fall to Earth.
Natural satellites are relatively small cosmic bodies that orbit larger “host” planets. In part, an entire science is dedicated to them - planetology.
In the 70s, astronomers assumed that Mercury had several celestial bodies dependent on it, since they detected ultraviolet radiation around it. It later turned out that the light belonged to a distant star.
Modern equipment allows us to study the planet closest to the Sun in more detail. Today, all planetary scientists in unison insist that it has no satellites.
Moons of the planet Venus
Venus is called Earth-like because they have similar compositions. But if we talk about natural space objects, then the planet named after the goddess of love is close to Mercury. These two planets in the solar system are unique in that they are completely alone.
Astrologers believe that Venus could have previously seen these, but to date not a single one has been discovered.
How many natural satellites does the Earth have?
Our native Earth has many satellites, but only one natural one, which every person knows about from infancy - this is the Moon.
The size of the Moon is more than a quarter of the diameter of the Earth and is 3475 km. It is the only celestial body with such large dimensions relative to the “host”.
Surprisingly, its mass is small - 7.35 × 10²² kg, which indicates low density. Multiple craters on the surface are visible from Earth even without any special devices.
What moons does Mars have?
Mars is a fairly small planet that is sometimes called red because of its scarlet hue. It is given by iron oxide, which is part of its composition. Today, Mars boasts two natural celestial objects.
Both moons, Deimos and Phobos, were discovered by Asaph Hall in 1877. They are the smallest and darkest objects in our comic system.
Deimos is translated as the ancient Greek god who spreads panic and terror. Based on observations, it is gradually moving away from Mars. Phobos, bearing the name of the god who brings fear and chaos, is the only satellite that is so close to the “master” (at a distance of 6000 km).
The surfaces of Phobos and Deimos are abundantly covered with craters, dust and various loose rocks.
Moons of Jupiter
Today, the giant Jupiter has 67 satellites - more than other planets. The largest of them are considered the achievement of Galileo Galilei, as they were discovered by him in 1610.
Among the celestial bodies orbiting Jupiter, it is worth noting:
- Adrasteus, with a diameter of 250 × 147 × 129 km and a mass of ~3.7 × 1016 kg;
- Metis - dimensions 60×40×35 km, weight ~2·1015 kg;
- Thebe, with a scale of 116×99×85 and a mass of ~4.4×1017 kg;
- Amalthea - 250×148×127 km, 2·1018 kg;
- Io with a weight of 9·1022 kg at 3660×3639×3630 km;
- Ganymede, which with a mass of 1.5·1023 kg had a diameter of 5263 km;
- Europe, occupying 3120 km and weighing 5·1022 kg;
- Callisto, with a diameter of 4820 km and a mass of 1·1023 kg.
The first satellites were discovered in 1610, some from the 70s to the 90s, then in 2000, 2002, 2003. The last of them were discovered in 2012.
Saturn and its moons
62 satellites have been found, of which 53 have names. Most of them consist of ice and rocks, characterized by a reflective feature.
The largest space objects of Saturn:
How many moons does Uranus have?
At the moment, Uranus has 27 natural celestial bodies. They are named after characters from famous works authored by Alexander Pope and William Shakespeare.
Names and list by quantity with description:
Moons of Neptune
The planet, whose name is similar to the name of the great god of the seas, was discovered in 1846. She was the first to be found using mathematical calculations, and not through observations. Gradually, new satellites were discovered until they counted 14.
List
Neptune's moons are named after nymphs and various sea deities from Greek mythology.
The beautiful Nereid was discovered in 1949 by Gerard Kuiper. Proteus is a non-spherical cosmic body and is studied in detail by planetary scientists.
Giant Triton is the iciest object in the solar system with a temperature of -240°C, and is also the only satellite that rotates around itself in the direction opposite to the rotation of the “master”.
Almost all of Neptune's satellites have craters and volcanoes on their surface - both fire and ice. They spew from their depths mixtures of methane, dust, liquid nitrogen and other substances. Therefore, a person will not be able to stay on them without special protection.
What are “planetary satellites” and how many are there in the solar system?
Satellites are cosmic bodies that are smaller in size than the “host” planets and rotate in the orbits of the latter. The question of the origin of satellites is still open and is one of the key ones in modern planetology.
Today, 179 natural space objects are known, which are distributed as follows:
- Venus and Mercury – 0;
- Earth – 1;
- Mars – 2;
- Pluto – 5;
- Neptune – 14;
- Uranium – 27;
- Saturn – 63;
- Jupiter - 67.
Technology improves every year, finding more celestial bodies. Perhaps new satellites will be discovered soon. We can only wait, constantly checking the news.
The largest satellite in the solar system
Ganymede, a satellite of the giant Jupiter, is considered the largest in our solar system. Its diameter, according to scientists, is 5263 km. The next largest is Titan with a size of 5150 km - the “moon” of Saturn. The top three is closed by Callisto, the “neighbor” of Ganymede, with whom they share one “master”. Its scale is 4800 km.
Why do planets need satellites?
Planetologists have always asked the question “Why are satellites needed?” or “What effect do they have on the planets?” Based on observations and calculations, some conclusions can be drawn.
Natural satellites play an important role for the “hosts”. They create a certain climate on the planet. No less important is the fact that they serve as protection against asteroids, comets, and other dangerous celestial bodies.
Despite such a significant impact, satellites are still not necessary for the planet. Even without their presence, life can form and be maintained on it. This conclusion was reached by the American scientist Jack Lissauer from the NASA Space Science Center.
The central star of our system, around which all the planets pass in different orbits, is called the Sun. Its age is about 5 billion years. It is a yellow dwarf, so the size of the star is small. It is not used up very quickly. The solar system has reached approximately the halfway point of its life cycle. After 5 billion years, the balance of gravitational forces will be disrupted, the star will increase in size and gradually warm up. converts all of the sun's hydrogen into helium. At this point, the size of the star will be three times larger. Ultimately, the star will cool down and shrink. Today the Sun consists almost entirely of hydrogen (90%) and some helium (10%).
Today, the satellites of the Sun are 8 planets, around which other celestial bodies revolve, several dozen comets, as well as a huge number of asteroids. All these objects move in their orbit. If you add up the mass of all the solar satellites, it turns out that they are 1000 times lighter than their star. The main celestial bodies of the system deserve detailed consideration.
General concept of the solar system
To consider the satellites of the Sun, you need to familiarize yourself with the definitions: what is a star, planet, satellite, etc. A star is a body that radiates light and energy into space. This is possible due to the thermonuclear reactions occurring in it and compression processes under the influence of gravity. There is only one star in our system - the Sun. There are 8 planets orbiting around it.
A planet today is a celestial body that revolves around a star and has a spherical (or close to it) shape. Such objects do not emit light (they are not a star). They can reflect it. Also, the planet does not have any other large celestial bodies near its orbit.
A satellite is an object that orbits another, larger star or planet. It is held in orbit by the gravitational force of this large celestial body. To understand how many satellites the Sun has, it should be noted that this list, in addition to planets, includes asteroids, comets, and meteorites. It is almost impossible to count them.
Planets
Until recently, it was believed that our system has 9 planets. After much discussion, Pluto was removed from this list. But he is also part of our system.
The 8 main planets are held in their orbits by the Sun. A satellite (planet) may also have celestial bodies orbiting around it. There are quite large objects. All planets are divided into 2 groups. The first includes the inner satellites of the Sun, and the second - the outer ones.
The planets of the terrestrial (first) group are as follows:
- Mercury (closest to the star).
- Venus (the hottest planet).
- Earth.
- Mars (the most accessible object for research).
They consist of metals, silicates, and their surface is hard. The outer group are the gas giants. These include:
- Jupiter.
- Saturn.
- Uranus.
- Neptune.
Their composition is characterized by a high content of hydrogen and helium. These are systems.
Satellites of the planets
When considering the question of how many satellites the Sun has, we should mention the celestial bodies revolving around the planets. In Ancient Greece, Venus, Mercury, Sun, Mars, Moon, Jupiter, Saturn were considered planets. It was only in the 16th century that Earth was included in this list. The sun has taken on its central significance in our system in the understanding of people. The Moon turned out to be a satellite of the Earth.
With the advent of more advanced technologies, it was found that almost all planets have their own satellites. Only Venus and Mercury do not have them. Today, about 60 satellites of planets are known, which are characterized by different sizes. The least famous of them is Leda. This one is only 10 km in diameter.
Most of these objects located in the orbit of gas giants were discovered using automatic space technology. She provided scientists with photographs of such celestial objects.
Mercury and Venus
Our star has two rather small objects closest to itself. The sun's satellite Mercury is the smallest planet in the system. Venus is slightly larger than him. But both of these planets do not have their own satellites.
Mercury has a highly rarefied helium atmosphere. It revolves around its star in 88 Earth days. But the duration of revolution around its axis for this planet is 58 days (by our standards). The temperature on the sunny side reaches +400 degrees. At night, temperatures down to -200 degrees are recorded here.
Venus's atmosphere consists of hydrogen with admixtures of nitrogen and oxygen. There is a greenhouse effect here. Therefore, the surface heats up to a record +480 degrees. This is more than on Mercury. This planet is best seen from Earth, as its orbit is closest to us.
Earth
Our planet is the largest among all representatives of the terrestrial group. It is unique in many ways. Earth has the largest celestial body orbiting among the first 4 planets from a star. The satellite of the Sun, which is our planet, differs significantly from all others in its atmosphere. Thanks to this, life became possible on it.
About 71% of the surface is water. The remaining 29% is land. The basis of the atmosphere is nitrogen. It also includes oxygen, carbon dioxide, argon and water vapor.
The Earth's satellite, the Moon, has no atmosphere. There is no wind, sounds, or weather. It is a rocky, bare surface covered with craters. On Earth, traces of meteorite impacts are smoothed out under the influence of the life activity of various species, thanks to wind and weather. There is nothing on the moon. Therefore, all traces of her past are reflected very clearly.
Mars
It is the final planet of the terrestrial group. It is called the “Red Planet” due to the high content of iron oxide in the soil. This is a fairly Earth-like satellite. It revolves around the Sun for 678 Earth days. Scientists believed that life could once exist here. However, studies have not confirmed this. The satellites of Mars are Phobos and Deimos. They are smaller in size than the Moon.
It's colder here than on our planet. At the equator the temperature reaches 0 degrees. At the poles it drops to -150 degrees. This world is already available for astronaut flights. The spacecraft can reach the planet in 4 years.
In ancient times, rivers flowed across the surface of the planet. There was water here. Nowadays there are ice caps at the poles. Only they do not consist of water, but of atmospheric carbon dioxide. Scientists theorize that water may be frozen in large clumps beneath the planet's surface.
Gas giants
Behind Mars are the largest objects that accompany the Sun. The planets (satellites of the planets of this group) were studied using various techniques. The largest object in our system is Jupiter. It is 2.5 times more massive than all the planets orbiting the Sun combined. It consists of helium, hydrogen (which is similar to our star). The planet radiates heat. However, to be considered a star, Jupiter needs to become 80 times heavier. Has 63 satellites.
Saturn is slightly smaller than Jupiter. He is famous for his rings. These are ice particles of various diameters. The planet's density is less than that of water. Has 62 satellites.
Uranus and Neptune are located even further than the previous two planets. They were discovered using a telescope. They contain a large number of high-temperature modifications of ice. These are the Ice Giants. Uranus has 23 moons, and Neptune has 13.
Pluto
The sun's satellites are also complemented by a small object called Pluto. From 1930 to 2006 it held the title of planet. However, after lengthy discussions, scientists came to the conclusion that this is not a planet. Pluto falls into a different category. From the point of view of the current planetary classification, this is a prototype. The surface of the object is covered with frozen ice made of methane and nitrogen. Pluto has 1 satellite.
Having studied the main satellites of the Sun, it should be said that this is a whole system consisting of a large number of different objects. Their characteristics and indicators are different. All these objects are united by a force that forces them to invariably rotate around their central star.
