Re: Sundial for Downed Pilots
Bill, BRILLIANT!!! You really suckered me in with that one. You are of course aware of the 2 - 4 Law which governs the distribution of people in the wild?? The number of people encountered in the wild is directly proportional to the square of the horizontal distance from the carpark, and the fourth power of the vertical distance above or below said carpark! Thanks for giving me a really good laugh! John Dr John Pickard Senior Lecturer, Environmental Planning Graduate School of the Environment Macquarie University, NSW 2109 Australia Phone + 61 2 9850 7981 (work) + 61 2 9482 8647 (home) Fax + 61 2 9850 7972 (work)
Re: Sundial for downed pilots
Art Carlson wrote: 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. [...] --Art Carlson Here are some rough parameters. The maximum deviation of the ecliptic from the equator is 23.5 degrees. In other words the maximum deviation of the point where the ecliptic meets the horizon from the true east or west compass point is 23.5 degrees. That's where my remarks about knowing the time of year and time of day comes in--it gives the information about this deviation. If you have a celestial planisphere, it probably has markings for the ecliptic and celestial latitude. Give it a good examination to get a feel for how the deviations behave over the course of a year and day. However, the moon does not lie precisely along the ecliptic, but can deviate from it by a maximum of about 5 degrees (I'm not certain of that max. deviation, and I don't have my books with me). Plus, there will be error in tracing out the ecliptic through the sky as I first suggested. In sum, the procedure I gave is pretty rough. Jim --- -- | Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] | | Parametric| Salt Lake City, UT | (801)-588-4632 | | Technology Corp. | 84108-1202 | Fax (801)-588-4650 | --- -- Through infinite mist, software reverberates In code possess'd of invisible folly. -- Curt Sampson
RE: Sundial for downed pilots
Hi Art, I agree totally. I provided the reference to the Survival Manual because it demonstrated how much you can learn by carefully observing and measuring with minimal equipment, the motions of the sun and stars. I am continually amazed at what this interest in sundials and the correspondence on this mailing list has taught me. Roger Bailey At 09:31 AM 5/14/99 -0700, Arthur Carlson wrote: I'm willing to (brashly) bet there was never a pilot who ever used these techniques or even took them seriously. Knowing your latitude and longitude without a map is useless, and if you have a map it is a lot easier and quicker to find your location from the terrain. If you can't find your location from the terrain because everything looks alike, an estimate of your latitude and longitude will not help much either. Mountains or rolling hills, possibly even forests, are likely to make a measurement of the length of the day too inexact to be useful. The only thing that is truly useful is finding directions, but then you should pack a compass, not a sextant. (That isn't to say none of this is fascinating.) I do think being able to look at the sun and estimate directions could be useful (in case you forgot to pack a compass, shame on you!). 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. With a Ph.D. in physics I think I can figure out how many hours to add or subtract in which direction to convert moon position to sun position and then to direction, but I bet very few people dumb enough to get lost at night without a compass can. But even without a watch, if you see the moon rising, you know that's east. And if the shadow is oriented straight up and down, then the moon is in the south. You don't need to know much more than that to find the nearest road. --Art Carlson
Re: Sundial for downed pilots
Arthur Carlson [EMAIL PROTECTED] wrote: I do think being able to look at the sun and estimate directions could be useful (in case you forgot to pack a compass, shame on you!). 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. With a Ph.D. in physics I think I can figure out how many hours to add or subtract in which direction to convert moon position to sun position and then to direction, but I bet very few people dumb enough to get lost at night without a compass can. But even without a watch, if you see the moon rising, you know that's east. And if the shadow is oriented straight up and down, then the moon is in the south. You don't need to know much more than that to find the nearest road. --Art Carlson 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 for the current date and time you can refine this indication of east or west direction. Jim --- -- | Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] | | Parametric| Salt Lake City, UT | (801)-588-4632 | | Technology Corp. | 84108-1202 | Fax (801)-588-4650 | --- -- With lies you may go ahead in the world, but you can never go back. -- Russian Proverb
Re: Sundial for downed pilots
A minute ago I 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 for the current date and time you can refine this indication of east or west direction. I should have been a little more specific here: 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. Jim --- -- | Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] | | Parametric| Salt Lake City, UT | (801)-588-4632 | | Technology Corp. | 84108-1202 | Fax (801)-588-4650 | --- -- Few things are harder to put up with than the annoyance of a good example.-- Mark Twain
