The Orion Nebula In The Daytime
NOV 10, 2010
The Orion Nebula is one of the brightest nebulae in the night sky. But,
even so, it is not bright by daytime standards. However, the light we
receive from the Orion Nebula is very special. The stars in the nebula are,
of course, just stars. Nothing special there. But, the glowing gas that
makes the nebula interesting produces light of only a few very specific
wavelengths. Most of it is so-called hydrogen-alpha
(H
a)
light, which is a deep red light having wavelength equal to 6563 Angstroms.
By using a filter that blocks out all of the light except for those
wavelengths in a very narrow band around 6563 Angstroms, it is possible to cut
out almost all of the light pollution and take a beautiful picture of the
nebula. Amazingly, this trick of using a narrow-band filter works so well
one can take a picture of Orion in the daytime. I took the picture shown at
right exactly at the moment of sunrise on September 9, 2007. Click on the
picture to see more pictures taken several minutes after sunrise as well as
a picture of the Sun reflecting off my neighbors window.
Narrowband Ha filters can be purchased from a few
different sources including
Astrodon,
Astronomik, and
Custom Scientific.
  --Bob