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Diurnal motion by latitude Somewhat related to this my picture showing only diurnal motion but Moon—seen from Earth—has a rapid motion with respect to the inertial celestial sphere, unlike stars and planets. Its motion relative to stars partially cancels the diurnal motion, and as the Moon’s orbit is inclined wrt Earth’s equator, Moon’s declination also changes and hence it can rise in 180°, 181°, 182°… or 360°, 359°, 358°… where objects moving only diurnally (such as stars and planets) cannot rise.

How far outside the polar circles can Moon rise in the Western celestial hemisphere or in north/south exactly? How is it best to see practically?


Also a meta request: where is a tag on astronomy.stackexchange about astronomy at high latitudes?

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    $\begingroup$ @Tosic: first of all, why namely “lower”? Second, the concept of “culmination” is only meaningful where the time derivative of d is negligible. Of course, we can determine with such a formula where an object crosses the meridian, but it won’t indicate where and when it will the highest or lowest on the sky. $\endgroup$ – Incnis Mrsi Nov 17 '18 at 7:48
  • $\begingroup$ Near a Major lunar standstill, the Moon's declination varies between -28.5° and +28.5°, approximately. That would put the theoretical limit near 61.5° of latitude, in reality, a bit lower due to lunar parallax. Although, in practice, I don't think that it could be easily observable at such a low latitude because the Moon would only graze the horizon (rise and set) in the South, near 180° azimuth. $\endgroup$ – FSimardGIS Nov 19 '18 at 0:16

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