[ExI] Hubble Ultra Deep Field 2014 image - in colour!
pharos at gmail.com
Wed Jun 4 04:50:54 UTC 2014
And, as Ethan Siegel [pints out -
Consider an image like this: 10,000 of the faintest, most distant
galaxies we've ever discovered. By measuring their redshifts, we can
determine (going back to Hubble's law) precisely how far away these
And as it turns out, about 40% of the galaxies in this image are
already unreachable, even for a beam of light that left today. If we
zoom in to this region of space and imagine what these galaxies look
like as far as "depth" goes, as in the video below, we'd find that
everything left in the image after about the 0:38 second mark has
already redded out.
And as the Universe continues on in time, more and more galaxies are
redding out as the Universe continues to accelerate. With each second
that goes by (on average) thousands of stars and their planetary
systems cross that horizon forever, and leave our ability to reach
them for all eternity. Of the hundreds of billions of galaxies (maybe
even as many as a trillion) in our Universe today, only about 3% of
them are still reachable.
Because the expansion marches on.
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