Editor’s Note: David Galadí Enríquez is a professor in the Department of Physics at the University of Córdoba, with a bachelor’s degree in Physics from the Granada and Barcelona units and a PhD in Physics, specialist in Physics of the Earth and the Cosmos.
It’s shocking to think about the loneliness that reigns on the far side of the Moon. Anyone who lived on it could go their entire life without knowing that there is a blue, living, watery and luminous planet nearby, because the Earth cannot be seen from there.
All observable objects show us both sides, except the Moon. No radio signal reaches its far side, and its silence and isolation are a strange oddity.
None of our radio or television transmissions reach the far side because the lunar mass blocks them. In the entire sphere of tens of light years through which news of Earth’s technological civilization is spreading across the galaxy, there is only one place where it would be impossible to become aware of such a marvel: the half that the Moon hides, the half of the star that , paradoxically, is closer to us.
Each US Apollo mission placed two white men on the visible face and left a third man circling the Moon inside the spacecraft. These astronauts were isolated from the rest of Humanity for almost 30 minutes in each orbit: Collins, Gordon, Roosa, Worden, Mattingly, Evans…transient “Robinsons Crusoe”, the only people in history who can say yes, they were alone.
Radio silence on the far side of the Moon makes it a good candidate for interference-free radio telescopes. But no one thought of landing there in the past. Of course, no astronauts have gone there, but even sending an automated probe would be futile, as it would be impossible to send data or communicate directly with Earth from these locations.
Flag of China
Everything changed when China sent space missions Cháng’é 4 and 6 to the far side of the Moon. The first landed there in January 2019 and landed a rover, while the second, which has just arrived, could bring it back to Earth soil samples from the intriguing Aitken Basin, at the lunar South Pole.
Before the arrival of Cháng’é 6, the Chinese space agency had to place relay satellites, orbiting just beyond the Moon, Quèquiáo 1 and 2, to enable communication. The incredible solution made the far side of the Moon no longer a place free of artificial waves. Humanity has already taken the “noise” there. Soon the trash will follow.
The Moon, in the half we see, has a painted face, those dark spots that outline the seas. Your other half… What will the other half be like?
The distant Moon, the hidden Moon, became an enigma when the telescope revealed that everything revolves in the Cosmos. If everything rotates, how is it possible that the silver ball on the Moon doesn’t rotate? If our natural satellite were rotating, as seen from Earth, the view of its disk would change over time, and it doesn’t. Something very strange was happening.
The reason for your hidden face
The explanation was provided by celestial mechanics. Just as the Moon exerts tidal forces on the Earth that raise the seas, our planet acts on the lunar sphere, and does so with much more intense tides. So much so that, over time, Earth’s tides elongated the Moon towards Earth, and forced it to rotate around its axis in the same time it takes to complete an orbit around our planet.
It’s not that the Moon doesn’t rotate, it does, it just rotates at the same speed as its orbital rotation. As a result of this synchronous rotation, from Earth we see only one side of the Moon, frozen, with no apparent rotation. Likewise, on the other side there is an entire invisible hemisphere, the far side of the Moon.
All objects in the observable Cosmos, without exception, show us their two sides over time. From the smallest asteroid to the Sun, from the most remote galaxy to an extrasolar planet around Proxima Centauri, everything goes around and around so that if you wait long enough and have a powerful enough telescope, you will in principle have access to all sides.
But the indifference of the lunar world, which is deaf and dumb, played this practical trick on us, courtesy of celestial mechanics: the closest star to the Cosmos is, at the same time, the only one, but the only one really, that hides half of its secrets of us.
In principle, there should be nothing special there. Cosmic processes are assumed to have been similar, and for centuries it was thought that the far side of the moon should resemble the visible side. But what greater sign of progress than flying beyond the Moon and discovering what has been hidden from all of Humanity throughout History? That’s what the Soviet Union set out to do in 1959, when it sent a technological prodigy at the time, the Luna 3 space probe, to map the invisible.
It’s the Earth’s fault
There was consternation: the hidden hemisphere of the Moon turned out to be very different from the visible one, almost completely devoid of dark seas. There is no “face” painted on the other side. However, since October 1959, the city of Moscow has had a sea, the Mare Moscoviense, on the far side of the Moon, and several of the most striking features on that side still bear Soviet names, such as the large dark Tsiolkovsky crater.
It’s not entirely clear why the far side of the Moon is so different from the one we see, but all explanations attribute it to the influence of Earth, an unusual inhabited planet that cannot be heard or seen from the far side of the Moon.
This article is republished from The Conversation. Read the original article.
Share:
