NavList:

Frank,

Many thanks for the extensive and informative reply.  I’m realizing that shadows work really hard: not only as anti-lunar indicators but also as Sun antipodal pointers, rainbow locators, and aircraft course finders.   Your commentary on contrails will forever affect my seat selection choices.  (Anti-Spoof Pro works in aircraft mode so I always have the Sun’s azimuth in my pocket.)

It also occurs to me that shadows played an important role a few millennia ago in determining the size of the earth.  As the story comes down to us, Eratosthenes used a stick about a meter long (sorta broomstick length) and measured its shadow at noon on summer solstice.  Given the precision of his ‘instruments’, he determined a surprisingly accurate value for the circumference of the earth.  Of course, the vast majority of NavListers will already know this; however, I’d like to add the suspicion that you and Eratosthenes might be distant relatives – you both do incredibly clever and creative things with broomsticks and shadows.

Thanks again, Frank.  Cheers to all.

Jim Wyse

48°N, 56°W