This photo of the constellation Orion, captures the differing colors of its stars by using the step-focus on each star's trail. This technique is created by varying the focus of the camera ens during each star's exposure, which dilutes the light and makes each star look larger and brighter as well as effectively illustrating the subtle color differences between the stars. For this particular photograph, the lens focus was moved from infinity to about 1 meter in a series of 10 steps about three minutes apart and a total of 35 exposures were combined to produce one picture. Betelgeuse, a cool red sugergiant star, clearly stands out here as the red blur towards the top left corner. Although Betelgeuse has a surface temperature of about 3600 K, which is significantly cooler than our Sun's surface temperature of 5800 K, it appears very bright because it has a very large mass and is actually about 20 times as massive as the Sun. The pinkish blur towards the center of the picture is the Great Nebula of Orion, which is basically a giant molecular cloud complex that is 1500 light years away, and scientists have discovered numerous infant solar systems in the nebula. Finally, the star W Orionis, which appears towards the bottom, is a Carbon star that has a magnitude of about 5.8 and is one of the few faint class C stars that can occasionally be seen by the naked eye. W Orionis is slowly becoming brighter and as it loses mass at the rate of a tenth of a millionth of a solar mass per year, it will shed its outer layers and become a white dwarf star.
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