It is a fact that any person who is contemplating the Moon from any point of the terrestrial globe will be observing, more or less, the same lunar phase.
If you could get a bird’s-eye view of the Moon orbiting Earth, you would see that our satellite rotates once on its axis every 27.3 days , which is also the same amount of time it takes to complete one orbit of our planet. The result is that from our perspective on land we see the same lunar hemisphere at all times and from any part of the Earth. At most, we can see a little more than half of the Moon’s surface thanks to an oscillation effect known as lunar libration (the set of oscillation movements that the disk of the Moon presents with respect to an observer located on Earth ).
There are three oscillations of the lunar globe : 1) libration in longitude, because the orbital speed of the Moon varies, 2) libration in latitude , because the lunar equator is inclined with respect to the plane of the lunar orbit by approximately 6º and, 3) diurnal libration, because, due to the rotation of the planet, the observer on Earth can see the lunar disk from different perspectives on the same day.
It was the Italian astronomer Galileo Galilei who first described the lunar libration, initially described as “wobble”.
Thus, if we take into account all these factors, even though the Moon is rotating, it always keeps the same face facing the Earth, since the time it takes to orbit the Earth and the time it takes to rotate on its own axis are the same. The Moon orbits the Earth once every 27.3 days and rotates on its axis once every 27.3 days. That’s why from Earth, the Moon always shows the same side.
Known as “synchronous rotation”, this is why we only see the near side of the Moon from Earth.
missions to the moon
This is precisely the reason why human beings have explored the closest side of the satellite with manned space missions. The “hidden” side, we have only examined with satellites in orbit. It was precisely in 1959 when the Soviet satellite Luna 3 photographed for the first time the hidden face of the Moon, the hemisphere not observable from Earth. The images taken by the USSR camera, a total of 29 photographs, covered 70% of the dark side of the Moon.
Since then, many satellites have sent back images and other data showing that the far or dark side (although it is actually the brighter side of our satellite) of the Moon differs from the side closer to us.
Basalt deposits (dark in color) fill many large basins on the near side of the Moon, while highlands on the far side are made of a light-colored mineral called feldspar. The Moon is covered in craters, and among the largest is the Aitken Basin, located at the south pole of the satellite. It is 2,500 kilometers wide and 8.2 kilometers deep. We owe its origin to a gigantic impact about 4.3 billion years ago.
And why when we see photos of the Moon from different areas of the Earth do they look so different?
People north and south of the equator see the current phase of the Moon from different angles. If you were to travel to the other hemisphere, the Moon would be in the same phase but would appear upside down compared to the other hemisphere . That is, the moon is seen the other way around from how it is seen by those who are in the north or south of the planet. Someone from Argentina does not see the moon in the same way as a person located in Canada. It all has to do with perspective and the curvature of our planet. It is a change in the orientation of the moon with respect to the horizon from which we look.
And why is the Moon visible during the day?
Now that we know that we all see the same Moon, have you ever wondered why you can sometimes see the Moon during the day?
Sunlight and the atmosphere play a key role in when and how we see our planet’s satellite. The answer is quite simple: both the Moon and the stars are always somewhere in the sky, but we can’t always see them because the Sun is so bright during the day that it drowns out the light of all other stars. During the day, the Moon is still up there, but we can’t see it.
In its rotation, it is visible to man when the sun illuminates the side facing our planet. Precisely because the sky has not reached its maximum brightness when it is very early in the morning, the moon is usually still visible although with much less clear tones.