NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sun squash- was Green Flash and Longitude
From: Glenn Geers
Date: 2006 Jan 16, 12:41 +1100
From: Glenn Geers
Date: 2006 Jan 16, 12:41 +1100
Ken Gebhart wrote: > On 1/14/06 9:24 PM, "Fred Hebard"wrote: > > >> Great post Ken. I can imagine it would be a lot of fun, or >> something, to try to work out a sight by hand while steering with >> one's knees! >> >> How would you measure squash? The altitude of the two limbs and >> assuming the SD for the width or the semi-diameter both ways? I >> don't know how to do semi-diameter with an aircraft sextant (or >> anything else with an aircraft sextant!). >> >> Fred >> >> > Thanks Fred, > > The idea is just a visual observation without a sextant. The ellipse > templates as mentioned, could be used to compare with the squashed sun to > get a good value. The entire squash phenomenon takes place during a 15 to > 20 minute period. The first discernable squash is at about 2%, and can best > be seen with the head tilted 90 deg to the side. For some reason we humans > can detect a slight ellipse with the major axis vertical rather than > horizontal. > > Ken > > I would suspect that preference for ellipses with a vertical major axis comes about from our innate ability to visually locate faces in all sorts of whacky backgrounds and environments. Ain't evolution grand. I know it's off topic. Cheers, Glenn