The Moon is the only natural satellite of the Earth. No one has ever been able to claim the credit for having discovered the Moon.

In the cover image you can see the blue full moon, Mexico, in October 2020. Credit: web “gq mexico magazine web”” Author: Alonso Martínez

Since ancient times, the Moon has been in the sky. Our beautiful satellite is there night after night awakening the curiosity and admiration of those who contemplate it.

This image of the Moon is considered one of the best on Wikipedia. Author: Luc Viatour

Physical characteristics of the Moon

The Moon, the only natural satellite of the Earth, is 384,400 km away: it takes just over a second for a ray of light to travel from the Earth to the Moon.

The lunar mean diameter is 3,476 km, less than a third of the diameter of the Earth which is 12,742 km.

If the Earth were the size of a basketball, the Moon would be the size of a tennis ball.

Moon Earth
Sizes compared moon and earth. Credit: web “”

Despite the fact that the diameter of the Moon is 3.6 times smaller than that of the Earth, its mass is 81 times less.

It is interesting to calculate at what point of the trip, the forces of attraction of the Earth and the Moon, cancel out with respect to the astronaut.

Astronaut Bruce McCandless is seen floating above Earth, in 1984. Credit: web “”

The Moon revolves around the Earth

It takes just over 29 days for the Moon to circle the Earth.

Blue Moon rising at night.  Credit: web “”

The spin of the Earth and the orbital motion of the Moon combine, in such a way that the rise of the Moon is delayed just over 50 minutes each day.

It is easy to observe that the Moon rises almost an hour later each day.

The hidden side of the Moon

Because the gravitational force of the Earth has completely slowed the Moon, it takes the same time to turn around on itself as it does to turn around the Earth.

For this reason, the Moon has a hidden face that has never been seen from Earth. Only when space research began, was it possible to know its hidden face.

The lunar farside as never seen before. Credit: NASA/Goddard/Arizona State University.

The ideal terrain to look at the skies is the dark side of the Moon.

There, in addition to the advantage of the lower force of gravity, there is no atmosphere and it is always night.

Researchers have calculated that a good telescope on the Moon could be 100 times more sensitive than the Hubble space telescope.

Hidden Moon
Details of the Hidden face of the Moon  Credit: NASA

Moon phases

The lunar phases are the apparent changes of the visible illuminated portion of the satellite, due to its change of position with respect to the Earth and the Sun.

Since the Moon revolves around the Earth, light from the Sun reaches it from different positions, which are repeated every turn.

When it illuminates the entire face that we see it is called a full moon. When we don’t see it, it’s the new moon.

Moon phaces
Photographic composition of seven phases of the Moon. Credit: web “

Between these two phases you can only see a piece of the moon, a quarter, waxing or waning.

Something similar happens when the Earth is viewed from the Moon. As in the image on the right, obtained by the Apollo 11 astronauts, where the Earth is seen from the edge of the Moon.

Moon Earth
Earth as seen by the crew of Apollo 11. Credit: University of Arkanzas, web “”

The first civilizations already measured time by counting the phases of the Moon. One week is what each phase lasts, and one month, approximately, the entire cycle.

Man’s incursion on the Moon

Since the 16th century, the Moon has continued to be the star that arouses the most curiosity to those who can observe it through a telescope.

In July 1969, a historical event occurred that completely changed our perception of the Moon: man managed to step on the Moon.

On the occasion of the Apollo 17 Mission, in 1972, the astronaut and geologist Harrison Schmitt was able to analyze some rocks on the Moon.

Moon rock
Astronaut Schmitt analyzing a rock on the Moon ,1972 Credit: web “”

You can take a great walk across the surface of the Moon, entering the Google website, dedicated to the Moon and which works in a similar way to Google Earth. Click here to enter the Google Moon.

NASA managed to capture sharp images of the far side of the Moon, using cameras from the twin probes of the GRAIL mission.

NASA’s GRAIL mission set out for the Moon on September 12, 2011 to explore the Moon’s crust and core.

Saturday, October 5, 2019 in the “International Observe the Moon Night”. Credit: web “” Author: Joe Winter