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Orion Nebula not as far as you might think |
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Written by Derek Kessler on
Monday, 08 October 2007
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 New measurements have yeilded a surprising result with respect to the distance of our galactic neighbors. The massive Orion Nebula, once thought to be 1565 light-years away (that's 9.2 quadrillion miles), has now been found to be nearly 300 light-years closer, at 1270 light-years, a much more palatable 7.5 quadrillion miles.
The measurements mean more than having to make fewer pit stops along the way, it means that everything we though we knew about Orion was wrong. As it turns out, the stars that astronomers have measured in Orion are also closer, and consequentially not as bright as they were believed to be. That means that they're either (1) older or (2) smaller, more likely the former than the latter.
The measurements were made by utilizing a technique called parallax, where images are made from the far ends of Earth's orbit around the sun. Astronomers measure the minute differences that arise from the images being taken at different angles with respect to the Orion Nebula, and from there can compute how far away the object is.
The Orion Nebula is one of the largest stellar nurseries known to man, measuring approximately 30 light-years across. It is classified as a diffuse nebula (it is illuminated by interior stars) and called both M42 (in the Messier catalog) and NGC 1976 (in the New General Catalogue). The nebula gets its name from the surrounding constellation in our night sky, Orion. The Orion Nebula is in fact part of a much larger nebula that spans a large segment of the sky - the Orion Molecular Cloud Complex - and contains several notable nebulae, including Barnard's Loop, the Horsehead Nebula, M43, M78 and the Flame Nebula.
Because of Orion's status as a bright stellar nursery, it is visible as a fuzzy spot to the unaided human eye (just below the middle of Orion's belt). With binoculars or a small telescope it becomes clear that it is a nebula. The Orion Nebula is one of the most studied stellar objects outside our own solar system, with official discovery being credited to Nicolas-Claude Fabri de Peiresc in 1610, though he believed it to be a comet. Unknown to Peirsec, the Mayan mesoamerican civilization that had died out over nearly a millenia earlier, had determined that the Orion Nebula was in fact no like the other stars in the sky. Aided by its position by the Cygnus Rift (a band of starlight-blocking dust in our local arm of the galaxy), the Maya believed that the Orion Nebula was the gateway to Xibalba - the underworld.
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