The Moon travels from East to West across the face of the Sun, not West to East. See the first video in the timeanddate.com link.
https://www.timeanddate.com/eclipse/solar/2017-august-21
Nope, as ICanScienceThat said, in the video Moon is going from right to left w.r.t. a viewer staring at the Sun.
I don't see the explanation.
In the following scenario a point on the Earth's surface is rotating faster than the Moon's rotation around the Earth, allowing the Moon to set in the West to all observers.
We are on the surface of the Moon when the Sun and Moon are lined up exactly with the Earth during the time of Solar Eclipse. We observe the Earth rotating.
![](https://i.imgur.com/LPFYPVu.gif)
North America is coming in from from the East Coast.
How does the shadow start from the West Coast?
Please explain.
Suppose a viewer from earth throw a laser ray to space, straight up vertical in the sky, without moving. If that ray hits the moon, it will run incredibly fast on its surface and will be seen, from a viewer on the Moon, as going from left to right. This is how the Moon is seen rising East and setting West.
Suppose you're on the Moon, in the center of the face facing the earth, and you're looking precisely in a direction parallel to sun rays (say that one sun ray connecting the sun and the earth) with a binocular limiting your view. To do so, your head will be slowly rotating clockwise. When you'll briefly see earth (once every 28 days), you'll see it going from right to left, as it was rising from west and setting to east. This is reflected on how we see the shadow due to eclipse (as Tumeni well explained)
Said in another way. The Moon surely see earth rotating, even if its speed is faster than earth's rotation. But for an observer on the Moon that looks only at a tiny part of the sky, following a straight direction (which requires uim to constantly move) will see Earth rising from West to East, once each 28 days.
The two viewers are not symmetric w.r.t. each others, they're actually contrained to experience the system in different ways, so their views aren't contradiction. They are different p.o.v.s
![Wink ;)](/Smileys/default/wink.gif)
If the Moon had a very long paint brush reaching to the Earth, it would be painting a line which travels Westwards. So the shadow must be traveling to the West.
It depends. If the brush on the Moon is parallel to the sun rays, it will paint earth once each 28 days, going from West to East. If the brush is perpendicular in the center of the face facing earth, than, it will keep painting earth 24/7, from East to West
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Now just for fun imagine that the Moon had a superfast speed and that, everything else being equal, it was rotating around you (humans on earth) in half day (instead of 28 days, wow!). Then:
- it would be seen rising West and setting East
- its daily eclipse shadow would be seen going from west to east too
Then suppose a veeeery slow Moon, taking 1000 years rotating around earth.
- it would be seen rising East and setting West
-
its eclipse shadow would still go from west to east, but on the ground it would be experienced as going from East to West
Finally, suppose the Moon had exactly the same angular speed of earth. This is again a very fast Moon.
- It would always be in a fixed position in earth's sky, never rising or setting.
- even though fixed, its motion w.r.t. the sun in the sky would be from West to East.
The b.e.p. occurs when the Moon goes as fast as a person on the Earth. In that case the shadow would be stationary on the ground.
So, in conclusions, the rising/setting direction is entirely due to the difference in angular speed. Instead, the shadow direction is dependent on the speed of the Moon. But these cases are quite simplifying the relative positions of the three bodies.