The Moon has always been a close yet unreachable companion. But the far side of the Moon, hidden from human eyes by synchronous rotation, remained a symbol of the unknown until the mid-20th century. Today, we know more about this hemisphere than ever before — but it is still there where the main mysteries of Earth's natural satellite remain hidden.

Why Can't We See It?

The reason is the so-called synchronous (tidal) capture. The Moon orbits Earth with the same period as it rotates around its own axis. The period of rotation coincides with the period of orbital motion, so only one hemisphere is visible from Earth. The far side is always turned away from us. It is not a shadow, not eternal night — it receives just as much sunlight as the visible side. Just its rays never reach the observer on Earth.

First Legends and Hypotheses

Before the space era, the far side of the Moon was an absolute terra incognita. Some astronomers speculated that there might be an atmosphere, water, or even unknown forms of life there. Science fiction depicted pictures of lost lunar civilizations. It was only in 1959 that the Soviet automatic station "Luna-3" made a historic flyby and transmitted the first photos. Humanity first saw what had been hidden for billions of years.

The Main Difference: Thin Crust, Mountains, and Almost No Seas

The first thing that amazed scientists was that there are almost no lunar seas on the far side, extensive dark areas filled with solidified basaltic lava. If on the visible side "oceans" and "seas" occupy about 31% of the surface, then on the far side their share is only 1–2%. The reason is related to the different thickness of the lunar crust. On the far side, the crust is significantly thicker, and basaltic magma could not break through to the surface to form smooth dark plains.

Instead, mountains dominate on the far side, craters, and the largest known impact structure in the Solar System — the South Pole-Aitken basin. The diameter of this giant crater is about 2500 kilometers, and the depth up to 13 kilometers. Many mountain peaks on the far side are higher than those visible from Earth.

"The Dark Side of the Moon" — a Misconception and the Legacy of Pink Floyd

The expression "the dark side of the Moon" is often used for the far side. But this is incorrect from an astronomical point of view. The far side is not dark — it receives sunlight during lunar days. The popularization of the term was facilitated by the cult album of Pink Floyd "The Dark Side of the Moon." Although the musicians invested a philosophical meaning in the name, the mythological nuance has become associated with the far hemisphere.

Soviet and Chinese Missions: How They Explored the Unseen

After "Luna-3," the Soviet Union continued its research. The "Zond-3" (1965), "Luna-12" (1966), and a series of orbital stations "Luna-10," "Luna-12," "Luna-14" accumulated detailed photos. However, it was only in 2019 that a new era in the history of humanity began: the Chinese probe "Chang'e-4" made the first soft landing on the far side of the Moon. The landing site was the crater Karman within the South Pole-Aitken basin. The landing module and rover "Yutu-2" have been working there until now, studying geology and radiation conditions.

Why Study the Far Side?

The far side of the Moon is an ideal location for radio astronomy. It is constantly shielded from Earth's radio noise, allowing observations in the low-frequency range that are not accessible due to the Earth's atmosphere and interference. Chinese engineers deployed the first experimental radio telescope in the crater Dager. In addition, the structure of the crust on the far side holds the keys to the early history of the Solar System: there are fewer signs of volcanic processing here, and the rock layers are older than those in the basaltic seas.

Myths About a Base of Aliens and a Spacecraft

Before the first photos, the far side was an ideal place for conspiracy theories. Stories were told about a secret Nazi base on the Moon, fragments of an alien spacecraft, and even a secret American mission. But all the photos taken since 1959 show a barren, rocky desert covered with craters. No artificial structures or anomalies have been detected by orbiting spacecraft.

The Future: The Next Stop — Even Further

The far side of the Moon remains a priority target. China plans the mission "Chang'e-6" to deliver soil from the South Pole-Aitken basin. Russia is considering the possibility of landing in the Boguslavsky crater as part of its lunar program. The construction of the first inhabited base on the Moon may also affect the far side if the low-frequency radio interferometer requires complete silence. However, engineering challenges are great: communication with the far side is only possible through satellite relay stations, such as China's "Queqiao" ("Magpie Bridge").

Conclusion: Not Dark, But Still Mysterious

The far side of the Moon has ceased to be invisible, but it has not stopped surprising. The thick crust, the absence of seas, the grandiose impact structures, and the scientific potential make it a unique laboratory. Space agencies are looking in its direction more and more actively, and perhaps in the coming decades, humans will finally step onto these edges — where the Earth never rises above the horizon.

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