I was looking at a very bright moon tonight through light cloud cover and saw a halo of light far bigger than the moon imposed on the clouds. Almost in a conic shape by comparison. I was wondering if early astronomers could use this difference to calculate the distance of the moon given the height of the cloud and the dimensions of earth.

  • $\begingroup$ @pm2ring the 22 degrees wouldnt aid a calculation of distance? $\endgroup$ – Magic Octopus Urn Oct 21 '18 at 4:43
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    $\begingroup$ I'm voting to close this question as off-topic because if it concerns the 22 degree halo, it is a meteology question. If it is not about this halo, it is unclear $\endgroup$ – James K Oct 21 '18 at 6:00
  • $\begingroup$ @PM2Ring that's a valid answer to this question, more than just a comment. $\endgroup$ – Glorfindel Oct 22 '18 at 9:13
  • $\begingroup$ Could be, because the question is based a misconception, but it's a question about (historical) astronomy, with a non-astronomic answer. $\endgroup$ – Glorfindel Oct 22 '18 at 9:45
  • $\begingroup$ @JamesK at the time I didn't know it was meteorological in nature. I've cast the final VTC vote, and accepted the answer posted. $\endgroup$ – Magic Octopus Urn Oct 22 '18 at 12:41

No, because the size of the halo is determined by the properties of ice crystals, the distance to the Moon is irrelevant. So you get a 22° halo with both the Sun & the Moon, even though the Sun's much further away.

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  • $\begingroup$ I shall, also I'll VTC my own question. Didn't mean it as meteorological, mostly because I didn't know it was meteorological. $\endgroup$ – Magic Octopus Urn Oct 22 '18 at 12:36

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