I have seen below statement, and it doesn't sound right:

The Sun and Moon seem to have the same size because of this amazing coincidence: the moon is 400 times smaller than the Sun and 400 closer than the Sun.

Checking 400 from this source:

The Moon's distance from the Earth: 384,000 km and diameter: 3,480 km
The Sun's distance from the Earth: 149,000,000 km and diameter of 1,392,000 km

Distance: 149,000,000 / 384,000 = 388.02, OK almost 400
Size: 1,392,000 / 3,480 = 400 spot on.

Does being X times further make it look X times smaller?

I have seen this post but not sure it answer my question: Can the apparent equal size of sun and moon be explained or is this a coincidence?

Note: First time post, let me know if the post is suitable.

  • $\begingroup$ The link you provide seems a duplicate of your question, imo $\endgroup$ – user140606 Jan 16 '17 at 12:50
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    $\begingroup$ Ah, the silent downvoters... $\endgroup$ – zx8754 Jan 16 '17 at 13:16
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    $\begingroup$ Yes the apparent equal size can be "explained" (as in the answer), and Yes, it is a coincidence. The earth's moon is HUGE relative to the size of the earth, compared with the moons of every other planet in our solar system. $\endgroup$ – alephzero Jan 16 '17 at 13:29

enter image description here

Also called the intercept theorem.


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