Saturday, 21 June 2014

distances - Why is the Eagle Nebula so "static"?

To add to Florin Andrei's answer, with an image height of 7,000 pixels for 14 light years, that's 17.5 light hours per pixel. That's 20 billion kilometres per pixel. To make a change in a single pixel over that time, something of that size must have either changed composition dramatically (to give a different colour or opacity) or it must have moved by a comparable distance.



Given the timeframe, that's a billion kilometres per year, or 123,000 kilometres per hour. (77,000 miles per hour, if you prefer) Few things that large are moving that fast relative to their neighbours.

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