The natural satellites of the Earth (that's right - in the plural) have occupied scientists for several centuries. Astronomers of the 19th and first half of the 20th centuries tried to find companions of the Moon. However, time after time, their assumptions and even convincing evidence turned out to be erroneous. Today, everyone from school knows that the only natural satellite of the Earth is the cosmic body of the Moon. Many other candidates are also of interest to astronomers, as they are not fictitious, but real-life objects that were mistakenly assigned the status of a permanent satellite of our planet.
Car
French astronomer Frederic Petit is well known to many people who are fond of studying celestial bodies. He was director of the Toulouse Observatory in the middle of the 19th century. Today, Petit is best known as a supporter of the theory that the Moon is not the only natural satellite of the Earth, but one of several. According to the astronomer, the role of her companionsfireballs approached (large and fairly bright meteors). Candidates for satellites circled the planet in an elliptical orbit. The most famous is the fireball that Petit observed in 1846. Summarizing the data - his own and other scientists - about the object, the astronomer concluded that the body rotates with a period of 2 hours 45 minutes, with perigee at a distance of 11.4 km and apogee at 3570 km.
Despite the fact that Frederic Petit's measurements and calculations were confirmed by some astronomers, his assumption was soon refuted. In 1851, Urbain Le Verrier provided evidence that the theory of the Toulouse scientist was wrong.
New guesses
Petit was not the only astronomer who tried to refute the conventional wisdom about how many natural satellites the Earth has. His colleague in this matter was a scientist from Hamburg, Dr. Georg W altemat. In 1898, he announced the discovery of a system of small satellites. One of them, according to the calculations of the scientist, was located at a distance of just over a million kilometers from the Earth and made one revolution in 119 days. The diameter of the hypothetical satellite was 700 km.
W altemath expected that the second moon would pass across the solar disk in February 1898, and this would be proof of the correctness of the researcher. The satellite was indeed spotted by amateur astronomers in Germany. However, none of the professionals observing the Sun that day noticed anything of the sort.
Another try
V altemat did not leave his search. In July of that year, he wrote an article about another candidate for the role of a lunar companion. A space body with a diameter of746 km circulated, according to the calculations of the author of the theory, at a distance slightly exceeding 400 thousand kilometers from our planet. However, these data also have not been confirmed. Hypothetical natural satellites of V altematha Earth failed to obtain the status of real-life objects.
Mystic
A feature of the satellite, "discovered" by V altemat, was the impossibility of observing it at any other moments, except for the time of passage through the solar disk. The object practically did not reflect light, and therefore was hardly noticeable. In 1918, astrologer W alter Gornold announced the rediscovery of the moon V altemath. He confirmed his "dark" nature and named Lilith (that, according to Kabbalah, was the name of Adam's first wife). The astrologer insisted that the second moon was comparable in mass to the first.
In the scientific world, these statements caused only a smile. Such a massive body would not go unnoticed, since its presence would have a significant impact on the Moon, which would be reflected in its movement.
Politics
Earth's natural satellite (Moon) or Mars and Venus, its closest neighbors, have always been associated with some secrets in the minds of people. In the past century, these space objects were often thought of as the dwellings of alien civilizations or military bases of unfriendly states. Against the background of such assumptions, the hypotheses about artificial satellites launched into orbit in an atmosphere of strict secrecy seemed more real.
At the beginning of the space age, in the middle of the last century, there were rumors about twosimilar objects. After some time, reports began to appear in the media about their natural origin. The excitement around new satellites died down in 1959, when astronomer Clyde Tombaugh (the scientist who discovered Pluto) after a long study of the space around the Earth announced that there were no objects brighter than 12-14 magnitudes.
Monitoring of near-Earth space
Today, few people do not know the name of the natural satellite of the planet Earth. The moon today is recognized as the one and only. However, astronomers constantly monitor outer space in the vicinity of our planet. The purpose of such a study is not to search for new satellites, but to protect against possible collisions, predict them, and ensure the safety of the stations. Clyde Tombaugh was one of the first to undertake this study.
Today, the search for cosmic bodies in near-Earth space is the goal of several large projects at once. So far, new natural satellites of the Earth have not been discovered in the process of research.
Quas-satellites
Of course, the Moon is not the only object in the vicinity of our planet. Research in recent years has provided a we alth of information of this kind. There are asteroids that are in 1:1 orbital resonance with the Earth. In the media and popular science literature, they are often referred to as "second moons". The main difference between such objects is the fact that they do not revolve around the Earth, but around the Sun.
A good example of such a cosmic body -asteroid (3753) Cruitney. It crosses the orbits of the Earth, Venus and Mars during its movement. The asteroid's orbit is highly elongated, but, unfortunately, it never comes close enough to our planet to be visible through weak equipment. Cruitney can only be seen with a sufficiently powerful telescope.
Trojans
There is another group of objects that are sometimes referred to as natural satellites of the Earth, but are not. These are the so-called Trojans - asteroids moving in the same orbit as our planet, but ahead or catching up with it. To date, only one such body has been confirmed to exist. This is asteroid 2010 TK7. It is ahead of the Earth by 60º. 2010 TK7 is a small (300 m in diameter) and rather dim object. Its discovery increased the interest of scientists in the search for Trojans in the vicinity of the Earth.
Optical effect
The question "how many natural satellites does the Earth" sometimes, although extremely rarely, arises simply when looking at the night sky. Under a certain set of circumstances, the simultaneous presence of several factors above your head, you can observe a phenomenon called a false moon. To do this, a full (or almost full) night star must be bright enough. A halo appears around him. Lunar rays are refracted in ice crystals of cirrostratus clouds and bright luminous points are formed on both sides of the satellite. The inexperienced observerfor some moments he can believe that where the natural satellite of the Earth (the Moon) or Mars and other planets plow space, new real-life space objects have appeared. However, the illusion quickly dissipates. The false moon, or parselena, is more like a play of light than it really is.
Dual system
The Moon, as the closest space object to the Earth, is always at the center of many research projects. Of course, not everything is known about her. A lot of controversy is still, for example, caused by the theory of origin. However, it can be safely called one of the most studied objects in space, as well as a marker, a hallmark of our home in the universe. The last fact is well illustrated by one of the versions of the flag of our planet, which depicts a natural satellite of the Earth.
The most interesting thing is that in the light of relatively recent studies, the status of the Moon is not so unambiguous. According to astronomers, the two most studied objects are a double planet. The natural satellite of the Earth and our space house revolve around the same center of mass. It is located not in the center of the Earth, but at a distance of almost 5 thousand kilometers from it. This hypothesis is also supported by the rather impressive dimensions of the Moon (and their ratio with the size of the Earth) compared to other satellites. An example of a similar system is Pluto and Charon, rotating around the same center of mass and always turned the same side to each other.
So, today everyone understands the name of the Earth's natural satellite and that it is the only one. The search for his companions left a noticeable mark in the history of astronomy and confirmed the well-known fact: a person is always not enough with what he has. However, it was thanks to this feature that many discoveries of the last century occurred.
