Solar system

The moon is our satellite

The moon is our satellite

The Moon It is the only natural satellite on Earth and the only body of the Solar System, in addition to the Sun, which we can see in detail with the naked eye or with simple instruments.

The Moon reflects sunlight differently depending on where it is in its orbit, which determines the moon phases. It revolves around the Earth and on its synchronized axis in the same period: 27 days, 7 hours and 43 minutes. This makes us always show the same face.

The Moon describes its orbit around the Earth at a speed of 3,700 km / h. and at an average distance of 384,403 km, almost 30 times the diameter of the Earth. Since the orbit is not circular, its apparent size is similar to that of the Sun or, at the furthest point, slightly smaller. This allows total and annular solar eclipses to occur, in addition to the partial ones.

How is our moon?

Is very large; It is not the largest satellite in the Solar System, but the fifth in size. But the four largest orbitam around giant planets. Our Moon has the largest size compared to that of Your planet, with a quarter of the diameter of the Earth.

Although it appears bright to the naked eye, the Moon only reflects in space about 7% of the light it receives from the Sun. This power of reflection, or albedo, is similar to coal dust.

It has no atmosphere or water, so the lunar surface does not deteriorate over time, if not for the occasional impact of a meteorite. The Moon is considered fossilized, a dead star.

Below are some Moon data:

Basic dataMoonThe earth
Size: equatorial radius1,737 km.6,378 km.
Average distance to Earth384,400 km.-
Day: period of rotation on the axis27.32 days23.93 hours
Orbit around the Earth27.32 days-
Average surface temperature (day)107 º C15 º C
Average surface temperature (night) -153 º C
Surface gravity in the equator1.62 m / s29.78 m / s2

There are several theories that claim to explain the origin of the Moon. The most accepted, the Great Impact theoryHe says it formed about 4.5 billion years ago, when an object the size of Mars crashed into an Earth still in formation. Some remnants of the impact remained in orbit and eventually formed our natural satellite.

The origin of lunar craters has been debated for a long time. Studies show that most were formed by impacts of meteorites traveling at high speed or small asteroids, especially during the primary era of lunar history, when the Solar System still contained many of these fragments.

However, some craters, lunar fissures and tops have characteristics that are unquestionably of volcanic origin.

The largest crater on the visible side is Bailly, 303 km in diameter and 4,260 m deep. The largest sea is the Oceanus Procellarum (Ocean of Storms), 2,500 km in diameter. The highest mountains have peaks up to 8,000 m high, comparable to the Himalayas.

Moon observation and exploration

The size of the moon, its regular cycle and its change in appearance have exerted an enormous influence on human history, on our culture and beliefs. If the observation of the solar position was at the origin of the clock, that of the moon is the basis of calendar.

Ancient observers believed that the dark regions of its surface were oceans, giving it the Latin name of "mare", which we still use. The brightest regions were considered continents.

Since the renaissance, telescopes have revealed numerous details of the lunar surface, and spacecraft have contributed even more to this knowledge. Today we know that the Moon has craters, mountain chains, plains or seas, fractures, summits, lunar fissures and radii.

On July 20, 1969, Neil Armstrong became the first man to step on the Moon, being part of the Apollo XI mission. Lunar projects have collected about 400 kg. of samples that scientists analyze.

Discover more:
• The theory of the Great Impact on the formation of the Moon
• History of astronautics: NASA's Apollo program
• The existence of water on the Moon, demonstrated with direct evidence


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The MeteoritesPhases of the Moon and eclipses