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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Time of planet rising
From: Chuck Taylor
Date: 2001 Dec 09, 3:27 AM
From: Chuck Taylor
Date: 2001 Dec 09, 3:27 AM
> 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
