WHY DO WE ALWAYS SEE THE SAME FACE OF THE MOON FROM EARTH?

Photo by Mike Petrucci on Unsplash
It's a question of rotating on own Axis. Rephrasing the title, I'd ask:

Why doesn't the moon rotate on its own axis like the earth does?

_________________
The moon does rotate about its own axis. If it didn’t it wouldn’t present the same view toward the Earth as it orbited around it. It rotates about its axis to present the same side to the earth at the same rate as it orbits around the Earth. This is called Tidal Locking, a phenomenon not just between the Earth and the Moon, but for all bodies orbiting each other in space. Their rotations about their own axes eventually fall into synchronization with their orbits. How long this takes depends on their mass. Pluto and its sister Charon which orbit each other are in a mutual tidal lock. Hence, we only got to see some of each during a probe fly-by as the portions facing each other were in deep shadow. The Earth, which is much more massive than the Moon, would eventually achieve tidal lock with the Moon in about 50 billion more years. That won’t happen as the Sun will become a red giant in about 5 billion years, swallowing the inner planets, including the Earth as it increases enormously in size.
_________________
In the meantime, the solar day - from solar zenith to solar zenith (local 12 Noon) is very, very, very slowly increasing, averaging about 1.7 milliseconds per century, as it slows toward what would be tidal locking if the Sun weren’t going to swallow it up before then. That’s a mere 0.034 seconds over the past 2000 years or roughly one second over the past 59,000 years. It’s something astronomers can now measure, and it is following theoretical prediction, but not something a person would notice.
_________________

Gifer

________________

 “Tidally-locked” bodies are pretty common in our Universe, based on what we’ve seen so far. This has big implications for how humans might live on the various moons of the Solar System someday, as well as how life may or may not emerge on tidally-locked exoplanets.

________________

Post a Comment

My instagram

Copyright © The Interdimension. All rights reserved.