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Subject: Re: Time of planet rising
From: Chuck Taylor (ctaylor@XXX.XXX)
Date: Sun Dec 09 2001 - 13:42:46 EST
> How can I determine what time a planet will rise?
The easiest way is to consult the diagram on page 9 of a current Nautical
Almanac (I'm referring to the US/UK almanac), "Local Mean Time of Meridian
Passage". The idea is to note, for a given date, the time of meridian passage
for a given planet. For example, it shows Mars crossing the meridian at 1700
LMT on 10 December. Since the Sun crosses the meridian at roughly 1200 LMT,
that means that Mars is 5 hours behind the Sun and will therefore rise
approximately 5 hours after the Sun rises and set approximately 5 hours after
the Sun sets.
In general, planets which appear below the shaded band in the middle of the page
are "morning planets" (visible before dawn), and those which appear above the
band are "evening planets" (visible after sunset). Those which appear within the
shaded band are too close to the Sun to be seen.
The logic is that if a planet (such as Mars) sets 5 hours after the Sun, it will
be visible for approximately 5 hours after sunset and then it will set.
The times derived by this method are of course not very precise.
Regards,
Chuck Taylor
Everett, WA, USA
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