On October 7th 1959, the soviet Luna 3 probe took the first picture of the far side of the moon.

It has been known since ancient times that the moon was a sphere. It would have doubtless been observed that the moon always seemed to present the same face to earth. The back face would have been a complete mystery, and I imagine suspect to much speculation.

The moon's libration allows attentive astronomers to see up to 57% of the lunar surface. Nevertheless, the thought of the unknown on the moon's far side must have been very tantalising to many astronomers, in the same way the appearance of Ceres and Pluto was to us prior to 2015, if not more strongly so.

Are there any interesting or notable historical theories on what the far side of the moon looked like or contained?

enter image description here enter image description here Top image: Luna 3 first image. Bottom image: Lunar Reconnaisance Orbiter composite image. Source: wikipedia

  • $\begingroup$ There were plenty of speculations about the Moon in general, starting with Plutarch and Lucian, but none of them focused on the far side specifically. Verne has his projectile fly over the far side when it is unlit. It is not like we can see the near side that clearly either, especially without a telescope. And in turn, only the near side of the Earth is visible from the Moon, so to the scientifically minded there was no reason to expect that the far side was much different. $\endgroup$
    – Conifold
    May 28, 2019 at 3:20
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    $\begingroup$ @Conifold I'd be shocked (!!) if 20th-century astronomers didn't have some guesses as to the density of meteor strikes on the far side. $\endgroup$ May 28, 2019 at 13:28
  • $\begingroup$ @CarlWitthoft I am sure they did, but crater density estimates do not exactly sound like "much speculation" over "a complete mystery" :) $\endgroup$
    – Conifold
    May 28, 2019 at 17:51
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    $\begingroup$ @Conifold "And in turn, only the near side of the Earth is visible from the Moon". Wrong, the Earth does rotate relative to the Moon. $\endgroup$
    – Leos Ondra
    May 29, 2019 at 17:09
  • $\begingroup$ Interesting question. I have been wondering if there were "Notable theories on Pluto pre New Horizons". What they found seems to have been mostly surprises. Should I Ask this Question? $\endgroup$ Jun 18, 2019 at 4:57


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