This actually something like the old way of determing the longitude (before there were accurate timekeeping instruments). It is called the Lunar Distance Method. I am sure there will be a number of references on the web.
At 08:12 16-3-00 -0700, you wrote: -----Original Message/Oorspronkelijk bericht-------------- >Hi Steve: > >It's an interesting thought to use the moon's shadow at sunrise and sunset >on the equinox to locate your east-west points. Although this can be done >with the sun, you would have errors using the moon, unless there is an >eclipse on the equinox also. If the moon is not in the same plane as the >sun, it will not act like the sun. > >Since the moon moves about two minutes/hour eastward in the sky, the only >way you can do this with precision is to use precisely calculated times and >lunar coordinates such as those sent to you by Jim Cobb. First you would >find the meridian with the moon, using Jim's data, then find east/west. > >If there was a lunar eclipse on the equinox, then you would have to have a >good unobstructed view of the east and west horizons which you probably have >or else you wouldn't have asked the question. > >For fun, though, let's make the moon readings anyway to see what happens! >We'll share our results after the event. > >Thanks for the luny question, > >John Carmichael > >>Hi all, >> >>It's only a few days to the equinox, which happens here in the middle of the >>night (3:35 AST). I'm going to use the previous evening and following >>morning to use a pole's shadow to make myself an East-West line, to compare >>to my existing NS meridian line. I hope to find that they are at right >>angles to each other. >> >>The moon becomes fully full just hours earlier, at 0:44 AST, so I'm >>wondering if I can do the East-West thing by moonlight too. Is it a valid >>thing to try? I've got a suspicion it only works when the equinox is also an >>eclipse, so that all the bodies are all in the same plane. If that is so, >>does the phase of the moon have any relevance, other than giving a strong >>shadow? Unfortunately, my understanding isn't good enough to answer my own >>questions. >> >>And are there any other special sundial-related phenomena which I should be >>looking out for? >> >>Steve >> >> > > ----------------------------------------------------------------- Thibaud Taudin-Chabot 52°18'19.85" North 04°51'09.45" East home email: [EMAIL PROTECTED] (attachments max. 500kB; for larger attachments contact me first)
