Natural satellites of the Earth (just like that - in the plural) have occupied scientists for several centuries. Astronomers of the 19th and first half of the 20th century tried to find companions of the moon. However, over and over again their assumptions and even convincing evidence turned out to be erroneous. Today, everyone from the school bench 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, since they are not fictitious, but really existing objects, which were erroneously assigned the status of a constant satellite of our planet.
Car
Many people who are interested in the study of celestial bodies, the French astronomer Frederic Petit is well known. He was director of the Toulouse Observatory in the mid-19th century. Today, Petty is known primarily 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, fireballs (large and fairly bright meteors) were suitable for the role of her companions. Satellite candidates circled the planet in elliptical orbits. The most famous is the car, which Petit observed in 1846. Summarizing the data - his own and that of 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 the measurements and calculations of Frederick Petit were confirmed by some astronomers, his assumption was soon refuted. In 1851, Urbain Le Verrier gave evidence of the fallacy of the theory of the Toulouse scientist.
New Assumptions
Petit was not the only astronomer who tried to refute the accepted opinion about how many natural satellites the Earth has. His associate in this matter was a scientist from Hamburg, Dr. Georg Valtemat. In 1898, he announced the discovery of a system of small satellites. One of them, according to the scientist’s calculations, 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.
Valtemat expected the second moon to pass through the solar disk in February 1898, and this would be evidence of the correctness of the researcher. The satellite was indeed seen by amateur astronomers in Germany. However, not one of the professionals observing the Sun that day noticed anything similar.
Another attempt
Valtemat did not leave his search. In July of that year, he wrote an article about another candidate for the role of the lunar companion. A cosmic body with a diameter of 746 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 did not receive confirmation. The hypothetical natural satellites of Valtemath Earth could not obtain the status of real objects.
Mystic
A feature of the satellite “discovered” by Valtemat was the impossibility of observing it at any other time, 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 Walter Gornold announced the reopening of the Walthamate satellite. He confirmed his "dark" nature and named Lilith (as, according to Kabbalah, the first wife of Adam was called). The astrologer insisted that the second moon was comparable in mass to the first.
In the scientific world, these statements have caused only a smile. Such a massive body would not go unnoticed, since its presence would have a significant effect on the moon, which would affect its movement.
Politics
The natural satellite of the Earth (Moon) or Mars and Venus, its nearest neighbors, have always been associated with some kind of mystery in the minds of people. In the past century, often these space objects were thought to be the abodes of alien civilizations or the 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 of two such objects. After some time, the media began to appear messages about their natural origin. The excitement around the new satellites subsided in 1959, when astronomer Clyde Tombo (the scientist who discovered Pluto), after a long study of the space around the Earth, announced the absence of any objects brighter than 12-14 magnitude.
Near Earth Monitoring
Nowadays, few people do not know what the name of the natural satellite of planet Earth is called. The moon today is recognized as the one and only. However, astronomers are constantly observing outer space near our planet. The purpose of this study is not to search for new satellites, but to protect against possible collisions, predict them, and ensure the safety of the stations. Clyde Tombo was just one of the first to engage in such a 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 research process.
Quasisatellites
Of course, the Moon is not the only object near our planet. Recent studies have provided a wealth of information of this kind. There are asteroids in orbital resonance with the Earth 1: 1. 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 rotate around the Earth, but around the Sun.
A good example of such a cosmic body is the Cruitney asteroid (3753). He during the movement crosses the orbits of the Earth, Venus and Mars. The asteroid’s orbit is very elongated, but, unfortunately, it never comes so close to our planet to be accessible for observation through weak equipment. You can only see Cruitney with the help of a sufficiently powerful telescope.
Trojans
There is another group of objects, which are sometimes designated 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 of or catching up with it. To date, the existence of only one such body has been confirmed. This is asteroid 2010 TK7. He is 60º ahead of Earth. 2010 TK7 is a small (300 m in diameter) and rather dull object. His 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 the Earth has" 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 the head, one can observe a phenomenon called the false moon. For this, a full (or almost complete) night star should be bright enough. A halo arises around him. Lunar rays are refracted in the ice crystals of cirrostratus clouds and bright luminous points form on both sides of the satellite. An inexperienced observer for some moments can believe that where the natural satellite of the Earth (the Moon) or Mars and other planets plow the space, new really existing space objects have appeared. However, pretty quickly the illusion will shatter. 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, for example, is caused by the theory of origin. However, it can be safely called one of the most studied objects of space, as well as a marker, a distinctive sign of our home in the Universe. The latter fact is well illustrated by one of the variants of the flag of our planet, which depicts the natural satellite of the Earth.
Most interestingly, 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 one 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 sizes of the Moon (and their ratio with the size of the Earth) in comparison with other satellites. An example of a similar system is Pluto and Charon, which revolve around the same center of mass and are always turned by the same side to each other.
So, today everyone understands what the natural satellite of the Earth is called and that it is only one. The search for his companions left a noticeable mark in the history of astronomy and confirmed the well-known fact: a person always has more than what he has. However, it was thanks to this feature that many discoveries of the last century occurred.