General information about the Moon

Moon (Latin: Luna) - the only natural satellite. This is the second-brightest object in Earth's sky after the Sun and the fifth largest natural satellite in the solar system. Also, is the first (and for the year 2008 only), an extraterrestrial object, which visited the people.

The magnitude of the Moon in Earth's sky-13m. The illumination of the full moon around the Earth's surface is 0.25 lux.

Origin of the Moon

The moon for its appearance and the fact that there have long been amazed thinking part of mankind. In ancient times, many people worshiped the moon as a god. The ancient Greeks may have first come to the Moon from a scientific point of view. In the third century BC. er. Aristarchus of Samos, observing the earth's shadow on the moon during a lunar eclipse, the distance to the moon in the sixty-Earth radii (a remarkable result: the current data, the radius of the Moon's orbit varies from 55 to 63 Earth radii). Plutarch thought that the moon can live people - selenites. It was believed that the dark spots on the Moon - it is the sea, and bright areas - land.

In 1609, Galileo Galilei discovered on the moon mountains and craters, making out in their shadows cast by the telescope. Based on his observations, Galileo concluded that the moon is a rocky body like the Earth. Since then, the puzzle of education of the moon reflected many generations of scholars, beginning with shmmanuila Kant and Rene Descartes. Since the early seventeenth century to the mid-twentieth there have been several major hypotheses, which had its supporters and its popularity rises. A new era in lunar exploration began in 1960, with flights to the Moon Soviet automatic stations and the American "Apollo". A new science - selenology. Were delivered to Earth samples of lunar rocks, which gave rich material for reflection and reassessment of old ideas.

It turned out that in many respects, the Moon is very different from Earth in the first place, the chemical composition: almost no water, low content of volatile elements and compounds. Lunar rocks suggest that the Moon underwent a complete meltdown, in contrast to the Earth. The density of the Moon is comparable with the density of Earth's mantle, it has almost no iron core.

However, we found many similarities and the Earth and Moon. Radioisotope analysis shows that both celestial bodies have approximately the same age: approximately 4.5 billion years. Ratio of stable isotopes of oxygen on the moon and on Earth coincides, as blood of one group - very different from a ratio of all known meteorites. This suggests that the Earth and Moon were formed in the neighborhood - from a substance at the same distance from the Sun in the protoplanetary nebula.

Before the scientists obtained samples of lunar soil, they knew nothing about when and how the moon formed. There were three principal theories:

    * Moon and Earth formed at the same time of the gas-dust cloud;

    * The moon was formed as a result of Earth collision with another object;

    * Moon formed elsewhere and was subsequently captured by the Earth.

However, the new information obtained through a detailed study of samples from the moon, led to the creation of the theory of the Giant collision: Earth faced with a very large object (like Mars, or even more), and the Moon formed from the ejected this clash of the substance. Not all details of this theory worked out, but that it now has the largest circulation.

According to estimates based on the rate of decay of an isotope of tungsten-182 in samples of lunar soil in 2005, scientists-metallurgists from the UK and Germany have identified the age of stones in the 4 billion 527 million years (± 30 Ma). This is the most accurate to date value.

Motion of the Moon

As a first approximation we can assume that the Moon moves in an elliptical orbit with an eccentricity of 0.0549 and semimajor 384,399 km. However, the actual motion of the Moon is difficult, and its calculation should take into account many factors, such as Earth oblateness and the strong influence of the Sun, which attracts the Moon at 2.2 times stronger than the Earth. More accurately the movement of the Moon around the Earth can be represented as a slowly unwinding spiral, resulting in an annual Moon moves away from Earth at a distance of 4cm.

Period of the Moon around the Earth relative to the stars is equal to 27.32166 days, the so-called sidereal month.

Since the moon does not light itself, but merely reflects the sunlight from the Earth is only visible sunlit portion of the lunar surface. The moon orbiting the Earth, and thus the angle between Earth, Moon and the Sun varies, we see this phenomenon as a cycle of lunar phases. Period of time between successive new moons is 29.5 days (709 hours) and is called the synodic month. That the length of synodic months longer than the sidereal, due to the Earth's motion around the sun: when the moon relative to the stars makes a revolution around the Earth, the Earth at this time is already 1 / 13 part of its orbit, and that the Moon was once again between the Earth and the Sun, it need an additional about 2 days.

Although the Moon and rotates on its axis, it is always facing the Earth the same side, ie the rotation of the Moon around the Earth and around its own axis synchronized. This synchronization is caused by tidal friction, which produced the Earth in the shell of the moon .. According to the laws of mechanics, the Moon is oriented in the Earth's gravitational field so that the Earth is directed semi-major axis of the lunar ellipsoid.

Lunar libration

Between the rotation of the Moon around its axis and its revolution around the Earth there is a difference: the moon revolves around Earth by the law of Kepler (unevenly, that is near perigee faster near the peak is slower). However, the rotation of the satellite around its own axis evenly. Chemin This makes it possible to look at the opposite side of the moon from the west or the east. This phenomenon is called optical vibration libration in longitude. In connection with the same inclination of the axis of the moon relative to the plane of the Earth might look on the reverse side from the north or the south. It is also the optical libration, but in latitude. These librations totally possible to observe about 59% of the lunar surface. The phenomenon of optical libration was discovered by Galileo in 1635, when he was convicted shnkvizitsiey.

There is also a physical libration due to the fluctuation of the satellite around the equilibrium position in relation to the displaced center of gravity, as well as under the action of tidal forces from the Earth. These oscillations are the so-called. physical librations, which amounts to 0,02 ° in longitude with a period of 1 year and 0,04 ° in latitude with a period of 6 years.

Conditions on the surface of the Moon

Since the Moon is almost no atmosphere at night, and its surface is heated up to +120 ° C, but at night or even in the shade, it cools down to -160 ° C. Also, the sky is always black on the moon, even during the day. Huge disk of the Earth looks like from the Moon 3.67 times larger than the moon from Earth and is hanging in the sky, almost motionless. Phases of the Earth, visible from the moon, directly opposite the moon phases on the Earth.

Moon's surface is covered by the so-called regolith - a mixture of fine dust and rocky debris produced from the collision of meteors from the lunar surface. Thickness of the regolith varies from a meter to tens of meters.

The influence of the moon on the tides

The gravitational force between Earth and the Moon cause some interesting effects. The most famous of them - tides. Gravitational attraction of the Moon is stronger on the other side of the Earth, which is turned towards the Moon and weaker on the opposite side. Therefore, the surface of the Earth, especially oceans, are drawn toward the moon. If we look at Earth from outside, we would see two convex, and both are directed towards the moon, but are on opposite sides of Earth. This effect is much stronger in the ocean water than in the solid crust, so that the bulge of water anymore. And as the Earth rotates much faster than the Moon moves in its orbit, the bulges move around the Earth once per day is two high points of the tide.

shssledovaniya Moon

Antiquity and Middle Ages

Moon has attracted the attention of people from ancient times. In II. BC. er. Hipparchus studied the behavior of the moon in the starry sky, determining the slope of the lunar orbit relative to Earth's ecliptic, and also revealed several features of motion.

Hipparchus deduced by the theory developed later astronomer Claudius Ptolemy of Alexandria in II. Mr. e., having written a book on the "Almagest". This theory was refined many times, and in 1687, after the discovery of Newton's law of universal gravitation, from a purely cinematic, which describes the geometric properties of the motion, the theory has become a dynamic, taking into account the motion of bodies under the action of forces applied to them.

shzobretenie telescopes allowed to distinguish finer details of the topography of the moon. One of the first lunar map was Giovanni Richchioli in 1651, he also gave the names of large dark areas, name them as "seas", which we still use today. These place names reflect the long-held notion that the weather on the moon similar to Earth, and the dark areas were allegedly filled with lunar water, and light areas were considered as land. However, in 1753 Croatian astronomer Ruggiero Boscovich proved that the moon has no atmosphere. The fact that the occultation, they disappear instantly. But if the moon had an atmosphere, the stars would go out gradually. This indicated that the satellite is no atmosphere. And in this case, liquid water on the lunar surface can not be, because it would instantly evaporate.

With a light hand of the same craters Giovanni Richchioli started to give names of famous scientists: from Plato, Aristotle and Archimedes to Vernadsky, Aviation, and Pavlov.

XIX century

New stage of lunar exploration was the use of photography in astronomical observations, since the mid XIX century. This allowed more detailed analysis of the lunar surface for detailed photos. These photos were taken, in particular, Warren de la Rue (1852) and Lewis Rutherford (1865). In 1881, Jules Janssen was a detailed "Photographic Atlas of the Moon."

In 1811, French astronomer Francois Arago discovered the phenomenon of polarization of light reflected from the lunar surface. The reason for this phenomenon is present on the surface of granulated soil, which reflects the light in general is better than the surrounding area. This explains the rays of light around the dark lunar craters left by the discharge of ground at impact.

XX Century

Since the beginning of the space era of our knowledge about the moon has increased significantly. Make-up of the lunar soil, scientists have even received his designs, a map of the reverse side.

For the first time the moon visited the Soviet spacecraft Luna 2 "September 13, 1959.

For the first time managed to look on the back side of the moon in 1959, when the Soviet probe Luna 3 flew over it and photographed with an invisible part of the Earth's surface. The reverse side of the Moon is an ideal place for astronomical observatories. Posted here optical telescope would not have to break through the dense Earth's atmosphere. A radio telescope for the Moon would serve as a natural shield from the solid rock thickness of 3500 km, which is securely closed to them from any interference from the Earth.

In the early 1960's it was apparent that in space the U.S. lags behind the Soviet Union. Kennedy said - landing a man on the moon will take place before 1970. To prepare for a manned mission NASA has fulfilled several space programs: "Ranger" - photographs of the surface, "Surveyor" (1966-1968) - a soft landing and shooting areas and the Lunar Orbiter "(1966-1967) - a detailed image of the lunar surface.

Was first photographed from lunar orbit during the flight, Apollo 8, "Sunrise Earth"

The U.S. program of manned lunar mission was called Apollo. The first landing took place July 20, 1969, the latter - in December 1972, the first man to walk on the moon, Neil Armstrong became an American (July 21, 1969), second - Edwin Aldrin. The third crew member Michael Collins remained in the rocket. Thus, the moon - the only extraterrestrial body on which the man visited the moon as well - the only celestial body, samples of which were delivered to Earth (USA delivered 380 kilograms, the Soviet Union - 324 grams of lunar soil).

Finding the American astronauts on the moon is being questioned by some authors (see lunar conspiracy).

The Soviet Union responded by sendi