[AZ-Observing] Re: specks flying in formation
- From: Tom Polakis <tpolakis@xxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Wed, 11 Oct 2006 18:00:36 -0400
---- 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
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