Here is what I remember: an old black and white movie on TV Sunday afternoon, perhaps in the 1970's, a scientist holding a Crookes Radiometer at the eyepiece end of a large telescope pointed at the night sky.
As the radiometer began to turn (shown below in the GIF) the scientists were able to reach some conclusion about whether a comet (or asteroid, or alien spacecraft?) would or would not reach the Earth.
I'm sorry; I know it's thin, but it's all I've got.
below: Image (GIF) of a Crookes Radiometer, from here.