Does Everyone On Earth See The Same Phase Of The Moon On Any Given Day?


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Asuka Jr. answered
Yes. The reason for this is simple:
Many questions regarding the Moon stem from two particular misunderstandings about the moon: 1) it's sheer SIZE. Our moon (did you know that the sun, moon and the earth are the only celestial objects that don't actually have a name? The official name of the sun is 'Sol' but that's just Latin for 'sun', the moon is 'Luna', Latin for moon, and the Earth? Terra. Which means earth, or dirt/soil.) in relation to the Earth's size is larger than ANY other planets' moon. (Pluto used to hold that distinction, but it's no longer considered a planet, so we win!) A full QUARTER of our size, and 1/81 its mass! And 2) it's rather large DISTANCE from us... I know it looks close to us when you see it in the sky, but actually it averages 384,403 kilometers (238,857 miles) away from the Earth. This distance is so vast, that a beam of light traveling at around 186,282 mi/sec (variances due to gaseous content of the space it travels through) takes over ONE AND A QUARTER SECONDS to reach the surface of the moon (or the Earth if yer goin the other way). Now I know, less than a second and a half doesn't seem very long, but we're talkin about LIGHT here. The fastest stuff there is! (well, under normal circumstances that is- I won't go into that here) Perhaps a better scale would help. If you were to walk around the ENTIRE EARTH (at the equator) almost FIFTEEN AND A HALF times, you would have walked the 'average' distance to the moon (it's orbit is elliptical, so the distance varies a bit).

Now, at a distance like that, there doesn't tend to be a lot of variance in appearance... Like in the way that if you and a friend are maybe 15 feet apart, looking at something that's say, 25 feet away from you both, you will both see different angles on the same thing, and might describe it differently because of that, but if you were both looking at something far larger but say a couple miles away, you'd pretty much see the exact same face of the something. Get it?
Now, since the moons' phase takes ample time to change from one state to the other, while no two people looking at the same thing at different times can be said to see the exact same thing (all things change in one way or another), the changes between when you would see something in the middle of YOUR night, and when someone on the other side of the world would see in the middle of THEIR night is sufficiently small as to consider you both to have seen the same state (and thus phase) of the moon as the other.

I hope that answers your question without boring you to tears, and you have a great day!

Asuka Jr.

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