From: Ulrich Mueller <ulm@gentoo.org>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: 61460@debbugs.gnu.org, Nicholas Strauss <nicholas.strauss@gmail.com>
Subject: bug#61460: 30.0.50; Calendar shows eclipse for quarter moon
Date: Tue, 14 Feb 2023 08:59:29 +0100 [thread overview]
Message-ID: <uh6vobrtq@gentoo.org> (raw)
In-Reply-To: <875yc4q0ee.fsf@web.de> (Michael Heerdegen's message of "Tue, 14 Feb 2023 06:30:33 +0100")
>>>>> On Tue, 14 Feb 2023, Michael Heerdegen wrote:
> I did not find good discussions of the eclipse limits in the English
> Wikipedia version; I found good explanations in German however:
> https://de.wikipedia.org/wiki/Finsternis-Limit#Finsternis-Limite_bei_Sonnenfinsternissen
Thanks. I followed the legend of the diagram and was pointed to the
following page, which contains a more comprehensive explanation:
https://www.swetzel.ch/astronomie/finster/finster.html#3
> The limits for an eclipse to happen are not really constant, but taking
> this into account is probably out of scope of the currently available
> code in lunar.el.
I wonder why the angles in above explanation are completely different
from the ones given in eclipse-check:
((< moon-lat 2.42600766e-1)
(concat "** " phase-name " Eclipse **"))
((< moon-lat 0.37)
(concat "** " phase-name " Eclipse possible **"))
These are in radians. The first angle is 13.9° (exactly) and the
second one is 21.2°. They are in argument of latitude, while (IIUC)
the angles in "Finsternis-Limit" are given in ecliptic longitude.
Still, with the moon's orbital inclination being only 5°, one wouldn't
expect much of a difference there. Or am I missing something?
I've also found the book mentioned in lunar.el:
https://books.google.de/books?id=vVBPtkABpUoC&lpg=PA186&vq=eclipse&hl=de&pg=PA177#v=onepage&q&f=false
CCing Nicholas Strauss (who had originally submitted the code in
bug #20414).
next prev parent reply other threads:[~2023-02-14 7:59 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-12 19:57 bug#61460: 30.0.50; Calendar shows eclipse for quarter moon Ulrich Mueller
2023-02-12 20:07 ` Ulrich Müller
2023-02-12 20:19 ` Eli Zaretskii
2023-02-12 21:13 ` Ulrich Mueller
2023-02-13 3:24 ` Eli Zaretskii
2023-02-13 3:25 ` Michael Heerdegen
2023-02-13 4:52 ` Michael Heerdegen
2023-02-13 5:13 ` Michael Heerdegen
2023-02-13 6:01 ` Michael Heerdegen
2023-02-13 7:28 ` Ulrich Mueller
2023-02-13 8:13 ` Michael Heerdegen
2023-02-13 8:52 ` Michael Heerdegen
2023-02-13 9:34 ` Ulrich Mueller
2023-02-13 10:04 ` Michael Heerdegen
2023-02-13 13:03 ` Eli Zaretskii
2023-02-13 13:30 ` Ulrich Mueller
2023-02-13 14:05 ` Eli Zaretskii
2023-02-14 5:30 ` Michael Heerdegen
2023-02-14 7:59 ` Ulrich Mueller [this message]
2023-02-14 9:15 ` Michael Heerdegen
2023-02-14 10:22 ` Ulrich Müller
2023-02-14 10:56 ` Michael Heerdegen
2023-02-16 20:26 ` Ulrich Müller
2023-02-17 5:25 ` Michael Heerdegen
2023-02-17 7:03 ` Ulrich Müller
2023-02-17 7:20 ` Michael Heerdegen
2023-02-18 5:53 ` Michael Heerdegen
2023-02-18 8:56 ` Ulrich Mueller
2023-02-18 9:16 ` Michael Heerdegen
2023-02-21 15:15 ` Michael Heerdegen
2023-02-22 9:00 ` Ulrich Mueller
2023-02-22 9:45 ` Andreas Schwab
2023-02-22 10:03 ` Michael Heerdegen
2023-02-22 11:32 ` Ulrich Mueller
2023-02-22 14:19 ` Michael Heerdegen
2023-02-22 15:46 ` Ulrich Mueller
2023-02-22 16:26 ` Michael Heerdegen
2023-02-25 16:13 ` Michael Heerdegen
2023-02-14 13:31 ` Eli Zaretskii
2023-02-14 10:49 ` Ulrich Mueller
2023-02-13 6:21 ` Ulrich Mueller
2023-02-13 7:08 ` Michael Heerdegen
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