Jim Cobb wrote: > Except for a new (which you can't see) or full moon, you can use the > terminator as an indicator of a perpendicular direction to the plane > of the ecliptic. Follow the implied ecliptic to either horizon to get > a sense of east and west. If you're familiar with astronomy and can > anticipate whether the ecliptic should be north or south of the > celestial equator [at the two horizon points ] for the current date > and time you can refine this indication of east or west direction.
That's exactly what I had in mind. This is a rule that can be easily understood and remembered, as opposed to remember to ADD nine hours to the clock time for a three-quarter moon, if it is WANING. What I would like to figure out is the errors involved in both methods, given orbital parameters. Ron Doerfler wrote: > > On my list of > > things I would like to do and know how to go about but haven't found the > > time is to investigate telling directions from the moon. I read an article > > in the magazine of the German Alpine Club a few years ago on this topic and > > found it incredible. > > Wow! Do you still have a copy of the article. I would > _love_ to read it. If you do have it, I'll be glad to > send a SASE. Maybe I have a copy or can get my hands on one, but not before September when I return to Munich. As I said, or meant to say, I was not impressed. The basic technique recommended was to figure out from the phase of the moon how many hours its position was ahead or behind the sun, then to assume east at 6 AM, south at noon, west at 6 PM, and everything else interpolated. It had no mention of errors or corrections for the seasons, the equation of time, or the orbital plane of the moon. Even so, the instructions were so complicated I'm convinced that no one who read the article could correctly recall them six weeks later. --Art Carlson
