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Credit:
David Malin
Explanation:
What determines a star's color?
Its temperature. Red stars are cool, with
temperatures of around 3,000
degrees Kelvin (K), while blue stars are hotter and can
have temperatures over 30,000 degrees K.
Our own lovely yellow Sun's temperature is a
comforting 6,000 degrees K.
Differences in star colors are dramatically
illustrated in the above photo of
the constellation Orion,
made using a "star trail step-focus" technique.
In this technique, a time exposure is used to create
star trails,
but during the exposure, the focus is changed in steps.
For the brighter stars, the blurred image
produces more saturated colors in photographs.
At the upper left,
the cool red supergiant Betelgeuse
stands out from the other, hotter, bluish stars composing
the body of the constellation.
Bright
Rigel, a blue supergiant, is at the lower right.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Orion
Publications with words: Orion
See also: