Number of known earth satellites. How many artificial Earth satellites are there? What is a satellite

Humanity has only just learned that the Earth has another satellite besides the Moon.

The second satellite of the Earth, astronomers say, differs from the big Moon in that it completes a full revolution around the Earth in 789 years. Its orbit is shaped like a horseshoe, and is located at a distance comparable to the distance from Earth to Mars. The satellite cannot approach our planet closer than 30 million kilometers, which is 30 times further than the distance to the Moon.

Relative motion of the Earth and Cruithne in their orbits.

Scientists say that the Earth's second natural satellite is the near-Earth asteroid Cruithney. Its peculiarity is that it intersects the orbits of three planets: Earth, Mars and Venus.

The diameter of the second Moon is only five kilometers, and this natural satellite of our planet will come to its closest distance to Earth in two thousand years. At the same time, scientists do not expect a collision between the Earth and Cruithne, which has approached our planet.

The satellite will pass from the planet at a distance of 406,385 kilometers. At this moment, the Moon will be located in the constellation Leo. Our planet's satellite will be fully visible, but the size of the Moon will be 13 percent smaller than at the time of its closest approach to the Earth. A collision is not predicted: the Earth's orbit does not intersect anywhere with Cruithney's orbit, since the latter is in a different orbital plane and is inclined to the Earth's orbit at an angle of 19.8 °.

Also, according to experts, in 7899 years our second moon will pass very close to Venus and there is a possibility that Venus will attract it to itself and thereby we will lose “Cruithney”.

The new moon Cruithney was discovered on October 10, 1986 by British amateur astronomer Duncan Waldron. Duncan spotted it in a photograph from the Schmidt telescope. From 1994 to 2015, the maximum annual approach of this asteroid to the Earth occurs in November.

Due to the very large eccentricity, the orbital speed this asteroid changes much more strongly than that of the Earth, so from the point of view of an observer on Earth, if we take the Earth as a reference system and consider it stationary, it turns out that not the asteroid, but its orbit rotates around the Sun, while the asteroid itself begins to describe ahead of the Earth a horseshoe-shaped trajectory, reminiscent of a “bean” in shape, with a period equal to the period of revolution of the asteroid around the Sun - 364 days.

Cruithne will approach Earth again in June 2292. The asteroid will make a series of annual approaches to the Earth at a distance of 12.5 million km, as a result of which there will be a gravitational exchange of orbital energy between the Earth and the asteroid, which will lead to a change in the orbit of the asteroid and Cruitney will again begin to migrate from the Earth, but this time in the other direction , - it will lag behind the Earth.

The Moon is the only natural satellite of the Earth. We were once so sure of this that we didn’t even give our moon a specific name. On the other hand, this is completely justified, because The Moon, being the brightest and largest object in the night sky, needs no further introduction. The remaining 6 satellites of the Earth are so small and distant that they can only be seen through powerful telescopes. In addition, they revolve around the Sun, but are influenced by the Earth's gravity.

One can argue for a long time about whether such objects are natural satellites, but since, so to speak, the official point of view on this matter has not yet been determined, then nothing prohibits classifying them as such. The International Astronomical Union, the leading organization in determining what this or that celestial body is and how this body should be correctly called, promises in the near future to give a clear definition of the concepts of “satellite” and “component of the gravitational system.” Therefore, for now we have this, we have it.

So, together with the Moon, the Earth has 7 satellites. 5 of them are quasi-orbital asteroids or simply quasi-satellites, another one belongs to the class of Trojan asteroids. Up to a certain point, both of them (in in this case other) were quite ordinary asteroids and rotated in their more or less stable orbits around the Sun, until one day they ran into a huge Earth, relative to their dimensions, as a result of which they fell into a 1:1 orbital resonance with the latter. In other words, the rotation of the Earth and the “captured” asteroids has been synchronized and now they make one revolution around the Sun in the same amount of time.

Otherwise, these two types are fundamentally different from each other, so we will consider each separately.

Quasi-satellites of the Earth

What is a quasi-satellite? In principle, it can become almost any celestial body that finds itself in a 1 to 1 orbital resonance with the planet. Despite completely coinciding orbital periods, quasi-satellites always have a greater eccentricity (the degree of deviation from the circle) of the orbit, and sometimes also a pronounced inclination relative to the ecliptic plane (the plane in which the planet rotates).

The main feature of quasi-satellites, as well as Trojan asteroids, is that at any given time they are exactly the same distance from the Earth as they were a year ago. Actually, for this reason they are considered natural satellites.

On the other hand, their “loyalty” to the planet is not always stable: the duration of the gravitational tandem can range from several orbital periods to hundreds of thousands of orbits.

Cruithney

The largest and most famous among the Earth's quasi-orbital satellites is an asteroid Cruithney (3753). It was discovered back in 1986 by an amateur astronomer and became the first known celestial body in the solar system to move in such a strange but stable orbit. Later, astronomers discovered similar companions to Venus, Jupiter, Saturn, Uranus, Neptune and even Pluto.

Unfortunately, we don’t really know what Cruitney is. This is an asteroid with a diameter of about 5 km. It rotates in a very elongated orbit inclined to the plane of the ecliptic, the perihelion (the point of the orbit closest to the Sun) lies between the orbits of Mercury and Venus, and the aphelion - between Mars and Jupiter.

We conducted an experiment: we asked our friends if they knew how many satellites the Earth has. Out of ten people, only one decided to clarify: “Which ones exactly? Natural or artificial? The rest remembered that the Earth has a satellite, the Moon, and they heard about some others. To dispel doubts on this issue, Beautiful World decided to tell us what satellites the Earth has and how they differ.

What is a satellite

A satellite is an object that orbits another object in space along a specific trajectory. Depending on their origin, satellites can be natural or artificial.

The Moon is a natural satellite of the Earth

There are 2 most common theories about how natural satellites appear

The Moon is the only natural satellite of the Earth. Now this fact is generally accepted, but in the 19th and first half of the 20th centuries, astronomers constantly assumed that the Earth had other satellites.

Hypothetical natural satellites of the Earth

A fireball is a bright and noticeable meteor.

Frederic Petit studied fireballs - fairly bright and noticeable meteors. According to his calculations, it turned out that some fireballs were moving in an elliptical orbit. Because of this, he suggested that these fireballs could be satellites of the Earth. The scientific community did not agree with his theory and pointed out to Petit errors in the calculations: for example, he did not take into account air resistance and did not take into account errors in the original data.

Letter from Georg Waltemath to Science magazine (Sience) in which he reports that he has discovered Earth's second satellite.

Georg Waltemath suggested that the Earth has 3 small satellites. He believed that the satellites in different times observed by many scientists, but mistook them for sunspots. Waltemath said that satellites are mostly invisible because they reflect little light. However, he calculated when the satellite would pass across the solar disk and be noticeable. Scientists Winkler (Jena, Germany) and Ivo von Benko (Pula, Austria) checked his statement, but did not see the satellite at the appointed time. Other statements about the observation of Earth satellites also appeared. Such statements were made by astrologer Hornold, amateur astronomer Spire, and scientist John Bugbee. None of these statements have been confirmed.

Quasi-satellites

Cruithney is a quasi-satellite, it is not a natural satellite of the Earth.

In the 21st century, scientists discovered celestial bodies that looked like satellites. These bodies were called quasi-satellites. Unlike the Moon, quasi-satellites orbit the Sun and are located from it at approximately the same distance as the Earth. Their orbits are unstable and they periodically approach the Earth. In popular science literature, quasi-satellites are called “second moons” or “second satellites.” This is a simplified name, but sometimes it causes confusion: at one time articles appeared on the Internet about the discovery of the Earth’s second natural satellite, Cruithne. In fact, Cruithney is a quasi-satellite.

Artificial satellites GLONASS - global navigation satellite system, Russian development

An artificial Earth satellite is a spacecraft that revolves around the planet in an elliptical orbit. This name usually refers to unmanned vehicles. There are many satellites in space: communications satellites, reconnaissance and navigation satellites, meteorological, astronomical and other research satellites.

Interesting things to see about space

There is now a lot of material about space that you can simply admire, even if you don’t understand anything in this area. If you like space, then Beautiful World recommends watching:

Google Moon. You can examine the surface of the Moon and find where the expeditions landed: https://www.google.com/intl/ru/moon/

Nasa Gallery. Especially cool section with photos of the day: https://www.nasa.gov/multimedia/imagegallery/iotd.html

Instagram Nas. Here they publish short videos of rocket launches, stunning photos and videos from space: https://www.instagram.com/nasa/

Roscosmos Instagram. Here are also photos and videos from space, especially many beautiful photographs of the Earth: https://www.instagram.com/roscosmosofficial/

Roscosmos TV studio. News, popular science programs and videos in Russian: http://www.tvroscosmos.ru/

P.S. The article is popular science and intended for beginners. That's why we wrote it in simple language, omitting complex terminology.

With wishes for memorable moonlit nights,

Anastasia Gorbunova.

The article was written for the Beautiful World.

The earth has two natural satellites

Asteroid with a horseshoe orbit

When someone up there was handing out satellites to the planets solar system- The land was deprived. She has only one natural friend - Luna. Even Mars has two satellites, and Mars is much smaller than our old lady. The planet Neptune has fourteen of them, Uranus has even more - 27, Saturn grabbed 62, and Jupiter went crazy - 67. But for many years there has been talk about the second satellite of the Earth called Cruithne. It has an outlandish orbit, resembling a horseshoe, and it takes 789 years for the second satellite of Gaia to pass it completely. Today, the younger companion is located from our planet at the same distance as Mars.

Cruithney - companion

By the way, Cruitney is just a baby. Its diameter is no more than five kilometers.

This is her problem, because due to her size she will soon cease to belong to the Earth.

Cruithney - unknown companion

Soon, of course, according to time.

Almost eight thousand years later, Cruithne will approach dangerously close to Venus, and she will capture her by the force of her gravity.

And Luna will again remain our only beloved daughter.

Well, what do you want to call Venus after that? To me too - the goddess of love. The plundering bastard!

Cruithney is an asteroid

But some serious scientists are not sad about this, because they do not consider Cruitney to be the second satellite, but, on the contrary, call the little one a bad word - asteroid 3753.

Cruithney is an asteroid

In addition, they claim that the Earth has a dime a dozen similar satellites.

It turns out that the Earth also behaves like a hunter and periodically captures the same asteroids.

Many of them revolve around our planet for some time (sometimes up to a year), and then return to solar orbit.

Solar system. Fifth in diameter, mass and density among all planets and the largest among terrestrial planets , which also includes Mercury, Venus and Mars . Look at the night sky and count the visible satellites. You can only see one satellite on it. Is this really true? As a rule, the planets of the solar system have several satellites. Jupiter has large number natural satellites- 67, and even Mars has two asteroids that act as satellites.

Maybe the Earth has other satellites?

The Moon is the only recognized satellite of the Earth

Official science answers that no, Earth has one satellite. At least for now. Maybe, formerly Earth had a larger number of satellites, and it was millions or even long billions of years ago. Oddities of the terrain on the other side Moon can be explained by a collision with a second satellite, which provoked surface defects tens of kilometers deep.

Satellites may come and go over billions of years of Earth's history.

For example, Mars has two satellites, but this was not always the case. Phobos , the large Moon, is moving in a spiral and is expected to crash into the planet within the next ten million years. And so in the future Mars will have only one Moon called Deimos.

Orbit of asteroid 2006 RH120

It is also possible for the Earth to capture an alien Moon. The largest satellite Neptune, called Triton , rotates around the planet in the opposite direction from the other satellites. This suggests that the Triton satellite actually captured one of the Kuiper Belt objects that came too close to this planet.

NASA photo of 2006 RH120

In fact, our planet has already captured a 5-meter asteroid with the short name 2006 RH120. It orbited Earth four times during 2006/2007 before it was flung back into outer space.

Thus, we can guess the course of events in the past.

In addition, our planet could have more moons, which have not yet been discovered because they are simply too small. Researchers estimate that there may be meter-sized asteroids in Earth's orbit that could remain there for hundreds of years before gravitational interactions will push them out again.

There are other objects that interact rather strangely with the Earth's orbit. Scientists do not consider them moons, but they are very close.

Orbit of asteroid 3753 Cruithne

Asteroid 3753 Cruithne is constantly in orbital resonance with Earth. It has a highly eccentric orbit that corresponds to exactly one year of the Sun's orbit. This asteroid moves slowly, making a horseshoe-shaped path across the sky. Since Cruithne's discovery in 1986, several other resonant near-Earth objects have already been discovered.

Asteroid 2010 TK7 is known as the Trojan asteroid. It moves in the same orbit around the Sun as the Earth, at a gravitationally stable point in space.

To sum up, we can answer - so far the Earth has only one satellite. Our planet may have had more moons in the past and could capture some in the future, but for now we must enjoy the one moon we have.

But this is the moon that was in our sky last night.

Best regards, Evgeniy Brik.