Humans have been on the moon many times, but the moon is hollow, or solid, this is still an unsolved mystery. The current mainstream view is that the moon is a hollow sphere, and the representative theory is “the moon is hollow.”
“Lunar Hollow” is a theory that the moon is a hollow planet. In the 1960s, many scientists put forward this theory based on the fact that the density of the moon is much lower than that of the earth. And now there is some evidence to support the lunar hollow.
In April 1970, when Apollo 13 explored the moon, the scientist pointed out that the moon was likely to be an intermediate hollow sphere by observing the echo of the “moon shock” that landed at that time. Moreover, the lunar rock brought back by the astronauts to determine that the density of the lunar surface rock is much larger than that of the earth’s rock. Based on these, we can further affirm that the moon is a hard, thick hollow sphere. The observation of the lunar orbital circulator also proves this from another aspect.
There are also some doubts about the “lunar hollow theory”. In fact, let alone the moon, even if the earth is hollow or solid, scientists have not yet reached a consensus.