RE: How Do Scientists Know It's Space Expanding Not Galaxies Moving?
August 10, 2017 at 11:52 am
(This post was last modified: August 10, 2017 at 11:53 am by vorlon13.)
It tells you how far away ALL the weird little yon beasties are in the LMC.
And then when you see one like one of them in something (presumably) much further away, you can noodle out that distance too.
Think of it as a series of ladder rungs going away from us. The more accurately we can calibrate the lower rungs, the more accurately we can judge items on rungs further and further away.
And there are parallel 'rungs' if you will, it isn't just a single chain of measurements that gets you distances further and further out.
For instance, radio telescopes can resolve supernova shells much further away than visible light telescopes can. We've already seen how by just using geometry we can get a very accurate distance to the 1987 LMC supernova. We can 'see' ones much further away with radiotelescopes, and we can therefore know how far away they all are.
And then when you see one like one of them in something (presumably) much further away, you can noodle out that distance too.
Think of it as a series of ladder rungs going away from us. The more accurately we can calibrate the lower rungs, the more accurately we can judge items on rungs further and further away.
And there are parallel 'rungs' if you will, it isn't just a single chain of measurements that gets you distances further and further out.
For instance, radio telescopes can resolve supernova shells much further away than visible light telescopes can. We've already seen how by just using geometry we can get a very accurate distance to the 1987 LMC supernova. We can 'see' ones much further away with radiotelescopes, and we can therefore know how far away they all are.
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