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REPORT COPYRIGHT VIOLATION IN REPLY
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Message Subject
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Calling Astro...Please come in and explain how this works???..It's freaking me out.....
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Poster Handle
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Anonymous Coward |
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Post Content
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That video explains in easy to understand terms why the place where you can see solar eclipse travels from west to east.
It's quite simple, really. So there's no need to argue over it.
Quoting: Anonymous Coward 78954816 I already proved that the video is wrong because the speed of the Earth and moon doesn't matter in this case, what matters is the angular speed of Earth's rotation and the angular speed of the moon's orbit around the earth. Did you not read my proof? I tried to read everything but I didn't quite get what you meant by that. The only thing that matters in my opinion is how fast the Earth rotates and how fast the Moon goes by that portion of its orbit where it's blocking at least some portion of the Sun from view on Earth. If you think about it, the Moon is just able to cover the Sun when a total eclipse is happening. So for a rough estimate, we can calculate the moon's diameter times two for the distance the Moon is covering at least some part of the sun when viewed from Earth. So all we have to do is take the Moon's diameter times two and divide it by the speed per hour the Moon is traveling at and that will tell us the time it takes for the Moon to travel across the Sun. So we'll take The Moon diameter and multiply it by two 3 474,2 km * 2 = 6 948,4 km and divide that by the speed of the Moon 6948,4 km / 3,700 km = 3,700 = 1,878 and that is how many hours roughly it would take for the Moon to go across the Sun if viewed from a single non-rotating point on Earth. The rotation of course makes the time a bit longer as the same point on Earth is traveling in the same general direction with the Moon. So that's my take on it and I'm fairly sure that's in the ballpark for this type of an example. You can see how the two hours of partial eclipse is faster than the rotation of the Earth and that's why the eclipse moves from West to East. The issue is this. A point on the Earth is travelling at 15 degrees per hour due to the rotation of the Earth, that is its angular speed. The moon in its orbit around the earth travels at 0.6 degrees per hour, again its angular speed. So if the Earth did not spin, the moon's shadow would certainly move from West to East, but since the Earth rotates through many more degrees per unit time than the moon in its orbit around the Earth, the Earth wins the race and therefore spins ahead of the moon's shadow, and therefore it will appear that the moon's shadow is traveling from East to West. But the Moon doesn't have to "win the race". It just has to go by the Sun. The Sun isn't that big and if you think about your field of view when looking up at the sky, the Sun doesn't take up many degrees of your vertical field of view. It actually takes about 0.5 degrees. Now if the moon goes roughly 0.54 degrees of its orbit per hour it doesn't take long to pass by the Sun. You can actually do the same calculation as I did before with kilometers but with degrees (distance 0.5 * 2 divided by speed 0.54) and it's pretty close to the same answer as before. You can see how going by the Sun in two hours or so would be much faster than the speed at which the Earth is rotating, right?
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