In the ionosphere there is a layer of sodium atoms.
The sodium atoms come from tiny meteors. The sodium atoms in this layer can be ionized by
use of a powerful laser producing
a tiny artificial star. The cylinder of ionization in the ionosphere is about a
meter in diameter but from the earth the wave front sensor is distant enough
from the ionization to see only a star size diffraction pattern. Ref 1
Return to calling page
Ref 1 Peninsula Astronomical Society talk by Dr. Clair Max
of UCSC, September 13, 2002.