Apparant MIR Wavering

Thomas A. Troszak (
Mon, 13 Sep 1999 08:36:54 -0400

In response to my reply regarding the apparent "wavering" of Mir,
Jonathan Dietrich sent me a link to an article on the web: 

that talks about the "Autokinetic Effect". I found it very interesting
and relevant to visual satellite observations.

I know that there is also a very obvious atmospheric disturbance to even
"stationary" stars and planets here in the mountains where the air is
always turbulent, even at night. Not only do they "twinkle", they
sometimes "wobble" too.

Us poor earthbound satellite observers are stuck looking at everything
in space through a "watery" haze of air, and are subject to a host of
"illusions" created by our own brains.

The other illusion that I have experienced while observing satellites is
what I would call "persistence of motion" (because I can't remember what
it is actually called). If you are looking out the back of a moving
train watching the tracks "moving away", and the train stops, the tracks
appear to keep moving. Likewise, when scanning slowly accross the sky
looking for satellites, a sudden stop will cause a brighter star to
appear to move, and for an instant my brain thinks it has found the
satellite moving the opposite way.

I supect that the binocular/tripod folks are much less subject to these
difficulties having a fixed frame of reference, but the optical
disturbance of the atmosphere itself should not be underestimated.

Clear, dark, unwavering skies to all!

Tom Troszak
Asheville, NC  USA
35.601 N
82.554 W