Physics Photo of the Week
Orion Nebula - in color. Color processing and Discussion by Emma Falcon
The Orion Nebula (also known as Messier Object 42 or M42) is an
emission nebula located beneath Orion’s Belt. Emission nebulas
are clouds of ionized gas which give off light of various colors.
This specific nebula is located around 1,600 light years away from
Earth. The nebula itself is 33 light years in width and contains
many young stars. These young stars are in various early stages
ranging from "not yet shining" to "possible formation of surrounding
planets". Astronomers have been watching the Orion Nebula closely
in hopes to discover the secret behind the birth of stars.
On clear nights, one can often see the Orion Nebula without the use of
a telescope. If one looks at the Orion constellation, the nebula
itself would be located in the center of Orion’s "sword" (a series of
three stars which hang from the infamous belt).
It is a long process in order to create the color image you see
here. First, multiple black and white images had to be taken
Orion Nebula (photos were taken by Brent
Figlestahler Dec. 2008 and described by Molly Herold for the Jan
23 PPOW) Later, multiple photos were taken of the nebula
using green, red and blue filters (Photos courtesy of both David Penketh and Molly Herold.) Each photo
taken with a 20 second time exposure.
Once there were enough photos through each filter (around 14 photos
each) the images were then calibrated and eventually stacked depending
on the color. Stacking the images removes a lot of the "noise" or
specks and blurs which play no importance within the image and results
in a much clearer image. The photos are stacked using the
computer to match up the stars within the specific images to insure the
whole assembly is aligned.
Now there are four images (Black and white, red, green and blue)
instead of the original 56. When looking at the four images there
is a noticeable difference within the amount of nebula visible within
each. This is because the stars give off ultraviolet waves due to
their high energy. These waves alter how the Orion nebula is
photographed and observed.
Finally, the four remaining images are stacked and colored
appropriately. Using the computer, the colors are balanced
properly (making sure that the colors are not bleached out and such)
and the final image remains.
Photo of the
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