The answer is not as simple as it might seem. It largely depends on whether we are talking about the current period or the history of the Earth in general? And how large is the celestial object entitled to be called the moon, and which is not? .. In which orbit should it move? Let's try to figure it out ...
The current round of interest in the moon is probably associated with super moon. In 2014, this interesting astronomical event was observed as many as three times. Selenium during this period seemed especially large and bright, approaching the Earth at a minimum distance.
But did you know that in the history of our planet there was a period when the moon generally occupied almost half of the earth's horizon? No, it was not larger than now, but simply located much closer.
This follows from current astronomical observations, according to which our Moon annually moves away from the Earth by several centimeters. So, once she was much closer than now. And sometime the time will come when she generally says goodbye to us.
And were there ever times when the moon was not there at all, and where did it come from? Scientists do not have an exact answer to this question. But there are already three hypotheses explaining the appearance of the moon.
According to one of them, the Moon formed with the Earth about 5 billion years ago, when the entire solar system was formed.
According to another, the Moon was once a roving celestial body and, flying past the Earth, fell into its gravitational trap. The gravity of our planet caused the moon to revolve around the earth.
Perhaps the most interesting is the third hypothesis, according to which the Moon was formed as a result of the collision of the Earth with another planet, the size of Mars, which some astronomers call Teia.
Theia, like the moon, flew past our planet. But she did not calculate her route and crashed into it from all over. As a result of the collision, so much energy was released that Teia, as the geologist Daniel Hervarts of the German University in Cologne believes, completely melted and turned into steam, like most of the earth's surface. Part of the evaporated rock material then returned to the Earth and formed its shell, while the other assumed a solid state, turning into Selena. So the moon appeared at the Earth.
However, many planets in the solar system have more than one satellite. According to NASA's Jet Propulsion Laboratory, Mars has 2 satellites, Jupiter has 66, Saturn has 62, Uranus has 27, Neptune has 13, and these numbers are constantly changing as new moons open.
And only our planet has only one satellite - Selena. But is it? It turns out, except for the Moon, which everyone knows, our planet has two more subtle satellites. They were discovered by the Polish astronomer A. Kordylevsky in 1956. However, to this very day, very few astronomers can boast that they have observed these clusters of cosmic dust - they are too rarefied because they consist of ... cosmic dust. And he moves along the same path as the real moon, and at the same speed. But one cloud of dust goes 60 degrees ahead of Selena, and the other is just as much behind. And both are located in the so-called libration points calculated by the French scientist L. Lagrange in the XVIII century. He proved mathematically that if the three bodies at the beginning of the movement are at the vertices of an equilateral triangle, their movement will be stable and the mutual attraction will last very briefly. What can not be said about objects that can be called the second or false moon.
Such pseudosatellites or quasisatellites are celestial objects whose orbits are similar to the orbit of the Earth. In this case, an orbital resonance arises between our planet and this object. But there is a pseudo-satellite in the orbit of the Sun, as is the Earth. And only occasionally do they intersect.
The current round of interest in the moon is probably associated with super moon. In 2014, this interesting astronomical event was observed as many as three times. Selenium during this period seemed especially large and bright, approaching the Earth at a minimum distance.
But did you know that in the history of our planet there was a period when the moon generally occupied almost half of the earth's horizon? No, it was not larger than now, but simply located much closer.
This follows from current astronomical observations, according to which our Moon annually moves away from the Earth by several centimeters. So, once she was much closer than now. And sometime the time will come when she generally says goodbye to us.
And were there ever times when the moon was not there at all, and where did it come from? Scientists do not have an exact answer to this question. But there are already three hypotheses explaining the appearance of the moon.
According to one of them, the Moon formed with the Earth about 5 billion years ago, when the entire solar system was formed.
According to another, the Moon was once a roving celestial body and, flying past the Earth, fell into its gravitational trap. The gravity of our planet caused the moon to revolve around the earth.
Perhaps the most interesting is the third hypothesis, according to which the Moon was formed as a result of the collision of the Earth with another planet, the size of Mars, which some astronomers call Teia.
Theia, like the moon, flew past our planet. But she did not calculate her route and crashed into it from all over. As a result of the collision, so much energy was released that Teia, as the geologist Daniel Hervarts of the German University in Cologne believes, completely melted and turned into steam, like most of the earth's surface. Part of the evaporated rock material then returned to the Earth and formed its shell, while the other assumed a solid state, turning into Selena. So the moon appeared at the Earth.
However, many planets in the solar system have more than one satellite. According to NASA's Jet Propulsion Laboratory, Mars has 2 satellites, Jupiter has 66, Saturn has 62, Uranus has 27, Neptune has 13, and these numbers are constantly changing as new moons open.
And only our planet has only one satellite - Selena. But is it? It turns out, except for the Moon, which everyone knows, our planet has two more subtle satellites. They were discovered by the Polish astronomer A. Kordylevsky in 1956. However, to this very day, very few astronomers can boast that they have observed these clusters of cosmic dust - they are too rarefied because they consist of ... cosmic dust. And he moves along the same path as the real moon, and at the same speed. But one cloud of dust goes 60 degrees ahead of Selena, and the other is just as much behind. And both are located in the so-called libration points calculated by the French scientist L. Lagrange in the XVIII century. He proved mathematically that if the three bodies at the beginning of the movement are at the vertices of an equilateral triangle, their movement will be stable and the mutual attraction will last very briefly. What can not be said about objects that can be called the second or false moon.
Such pseudosatellites or quasisatellites are celestial objects whose orbits are similar to the orbit of the Earth. In this case, an orbital resonance arises between our planet and this object. But there is a pseudo-satellite in the orbit of the Sun, as is the Earth. And only occasionally do they intersect.
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