Two Moonset times in the nautical almanac ?

[rascalsailor]

Hi
In the current nautical almanac daily page for June 20 to 22,
can anyone explain the two times given for moonset for latitude 62 degrees north?
(See the image)

regards
Russell

[CarlosPindle]

Hi
In the current nautical almanac daily page for June 20 to 22,
can anyone explain the two times given for moonset for latitude 62 degrees north?
(See the image)

regards
Russell

Russell,

I think it means that at N 62° on those days of June 20 through June 22 the Moon is continuously below the horizon.
Not really sure but will give it more thought.

Carlos

[PeterB]

EDIT:

  OK.  I made a mash of my first post on this subject.  I was pondering the question and pulled out my Nautical Almanac for 2024. Then I proceeded to look up the wrong numbers by simple carelessness. My apology if I confused a few readers.

  Yes, there are two moon sets on Thursday June 20th at 62°N but now (hopefully) my references make more sense.

  On Wednesday June 19 the moon rises at 19:55 at latitude 62°N. That moon does not set on the 19th but rather on Thursday, June 20 at 00:06

   Then the moon rises again on Thursday, June 20 at 22:03 and sets again on Thursday, June 20 at 23:52 having been up for a very short time for a nearly full moon.

   On Friday, June 21 there is no moon rise and no moon set. The moon is never visible at 62°N on Friday.

    I think I 've got it right this time. Sorry for any confusion I may have caused. A rookie goof -- but the occasional blunder in the tables is also part of the reality of Cel Nav.

    Very interesting.

    Thanks for bringing it to our attention

          PeterB

[CelNav57]

Greetings all,

Here's a simple explanation;

"The shaded background just highlights that there are two such occurrences on that particular day. Considering them chronologically, on Thu at 62°N we have:
 
  A moonset at 00:06
    A moonrise at 22:03
    A moonset at 23:52

The moon is visible up to 00:06, until the next moonrise at 22:03 when it remains visible for 1 hour and 49 minutes. To see if this makes sense, we’d have to look for a moonrise near the end of the day earlier (Wed) because we’re so close to the ‘black rectangle’ that indicates no moon is visible the whole day. The last event on Thu is  the moonset at 23:52, which agrees with the ‘black rectangle’ (no moon visible) on Fri and Sat (i.e. the moon doesn’t rise again). We can also determine that for most of the day the moon is invisible on Thu (for roughly 22 hours).

That should also be close to what we see at 60°N on Thu: a moonset at 00:36 followed by a moonrise at 21:09, i.e. not visible for 20 hours 33 minutes. And the length of time it’s visible increases as the latitude goes South".

Does that make any sense? I had help with that answer as I made it too difficult to understand.

Johannes H.

[rascalsailor]

Thanks for all the replies. That makes sense, at that high latitude two moonsets occured.
Regards
Russell