This supernova was seen in 1987. It was 168,000 light tears away. This means it exploded more than 150,000 years before it was created. The distance was determined by measuring the size of several gaseous rings (planetary nebula) that were illuminated by the initial flash.
2007-11-20
09:44:12
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15 answers
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novangelis
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Society & Culture
➔ Religion & Spirituality
Although the group velocity in a laser beam can be accelerated, the front velocity has never been accelerated. You would require the front velocity to change.
You can determine the distance to an object, if you know the size of the object (which can be determined by the time it takes light to illuminate it from a central source), its size on an image, and the magnification of the image. No tape measure necessary.
2007-11-20
10:08:24 ·
update #1