Here's an amazing NASA photo gif of the Moon passing in front of the Earth from a million miles away. It also shows the back side of the Moon that we never get to see from Earth because that side is always facing away from the Earth.
Distance to the moon is about 362,000 km when it's near and when it's far, about 405,000 km.
The reason for this difference is that the moon's orbit around the earth is almost a circle, but not quite. The moon's orbit is slightly elliptical.
This shows 2 circular orbits gravitationally attracted. But the Moon's orbit around the Earth is slightly elliptical.
This shows a very elliptical orbits, much more elliptical than the Moon's orbit. Source: wikipedia.org
Here's a hint anyone can look up on wikipedia.org
Earth's mass is about 5.97237×1024 kg
Moon's mass is about 7.342×1022 kg
It's really not a hard math puzzle to figure out.
You can consider center of mass or levers, etc.
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Win 1 SBD for the first one that can calculate how much the Earth wobbles off center due to the Moon's elliptical orbit. Must post it in the comments here and show some simple math for how you arrived at your answer. And don't forget to upvote this post. Winner will be announced after the 7 days of the original post.
Time is running out. Here is the original post from 5 days ago:
https://steemit.com/education/@point/light-simple-and-strange-simple-math-to-play-with-win-1-sbd
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Thank you for considering this.
I will post the answer and the winner (if we have one) in a couple of days.