FreeLists / az-observing / [AZ-Observing] Re: specks flying in formation

[Tom Polakis <tpolakis@xxxxxxx>]

---- Jennifer Polakis <m24@xxxxxxx> wrote: 
> Tom worked out the trigonometry while I studied up on the Pacific Flyway...


To be trigonometrically serious for just one moment, the moon turned out to be 
far too high for the birds to be very far away.  The moon's altitude was fully 
10 degrees, meaning that the birds' altitude above the ground had to be about 
one-sixth of their distance.  So the birds would have to be flying up there 
with the SR-71's at more than 50,000 feet if they were 60 miles away.  20 miles 
distance produces 18,000 feet -- probably still a bit too high, and 5 miles 
gives 4000 feet.

If they were truly "specks" at 60x, then their apparent (magnified) size was 2 
arcminutes or so.  That means the actual angular size was 2 arcseconds.  At 5 
miles, 2 arcseconds corresponds to a bird that is 3 inches in diameter.

So there you have it.  It was a flock of little brown jobs migrating from 
Scottsdale to Chandler, commuting via the Loop 101.

Tom
--
See message header for info on list archives or unsubscribing, and please 
send personal replies to the author, not the list.