On Sun, 29 Jun 2008 08:24:13 -0700, AES wrote:

In article ,
Stealth Pilot wrote:

at 4,500ft (the original question) the aircraft has no shadow at all
but at the sub solar point (were you'd think the shadow should be)
there is a distinct bright area tracking along under the aircraft.

for thirty years this quietly puzzled me. it is a fact that aircraft
at altitude have no shadow. below them tracking along the ground is a
bright spot of light.

the reference I gave gives details of some original work by Fresnel
which proposed that light passing beside a gravitational mass should
be bent slightly by the mass and behind the body there should be a
bright spot. this seems to me to be the explanation for the absense of
the shadow. the mass of the aircraft acts as a gravitational lens and
this causes the bright spot.

Poisson spot, Spot of Arago, Keller edge waves. Very much doubt
gravitational bending of light is involved.

I looked up explanations and graphics of these effects.
the poissons spot demo looks entirely different from what I see.

I'm still happy with my explanation.

Stealth Pilot