# Distance to the Moon

who does not stare clear serene night at the eternal companion of the Earth - a mysterious and attractive moon?From afar it seems flat and nearly white, but what she really is, what distance to the moon?It is a natural satellite of the Earth, which has a spherical shape and a diameter of 3480 km.If you resort to the aid of a telescope, you can see her face all covered with rocks.Scientists have proved that the moon completely missing the atmosphere, and thus excluded any life.Hypothesis of the origin of the moon quite a lot, but to a unique solution, scientists have not yet come.It is possible that the collected evidence is gradually slightly open the veil of secrecy.

distance from the Earth to the Moon, calculated between their centers is 384,399 kilometers or 0.00257 astronomical units.If you compare it with the diameter of our planet, the path to the satellite will be 30 Earths.Interestingly, in contrast to the Earth's orbit, the Moon's orbit elliptical, so the distance to the Moon periodically changes its value.

in the 2nd century BC, about the property of the planet already knew scientist Hipparchus.He was able to calculate the average distance to the moon, almost correspond to the current value.He first calculated that it is equal to 30 Earth diameters.Another scientist, Aristarchus of Samos, in his writings, "On the magnitudes and distances of the Sun and the Moon" is still in the III.BC tried to calculate the distance between the two celestial bodies.He took as a basis the fact that the moon has a shape approximating to spherical, and that it shines the light reflected from the sun.He believed that the moon is in a certain phase and looks half-disks, it forms a geometric shape in the form of a triangle with a right angle.But, unfortunately, the scientist made a mistake in calculations 20 times since it was impossible to determine exactly when the Moon is at the top of the right angle.

Today, distance to the moon is determined by several accurate ways.Known method of triangulation of the two most distant points on Earth.Another method is based on the use of laser is that the laser is measured by the signal sent to the moon, and then received back.The essence of it is that on the moon, scientists used a specially installed corner reflector.The laser signal is sent from Earth to the reflector, thus accurately set the time of dispatch.Sent and the reflected light of the moon for some time returned to the telescope.Calculating the exact time in which the beam has passed the distance from the Earth to the Moon and came back, determined by the distance from the radiation source to the reflector.

example, the nearest point to the Earth orbit the distance to the Moon is 363,104 km, while removing more precisely at the apogee, it is equal to 405,696 km.As a result, the distance can differ by almost 12%.

Earth and Moon do not point the body, so to determine the shortest distance between them do the following calculation: from a distance at perigee subtract the sum of the radii, which are equal to 6378 and 1738 km.The resulting outcome is the required minimum distance between the surface of the Moon and the Earth, which is equal to 354,988 km.

If we went on foot to a distance equal to the distance from the Earth to the Moon, walking at a speed of 5 km / h without stopping, then it would be overcome only through 9 years.Flying on a plane at a speed of 800 km / h would be shorter, it would allow us to go to the moon in 20 days.

In reality covered the distance to the moon, American astronauts on the spaceship "Apollo".They were the first people who walked on the moon, and there was a significant event on July 20, 1969. For this, they needed 3 days.The fastest way - is to fly with the speed of light, which is equal to 300 thousand. Km / s, and the moon will be attainable through a light 1.25 seconds.