How Far Can Eye See?

eye see andromeda

Your eyes are very sensitive, able to detect just a few photons of light. If you take a look on a very clear night at the constellation of Andromeda, a little fuzzy patch of light is just visible with the naked eye. If you can make out that tiny blob, you are seeing as far as is humanly possible without technology. Andromeda is the nearest large galaxy to our own Milky Way. But “near” is a relative term in intergalactic space – the Andromeda galaxy is 2.5m light years away. When the photons of light that hit your eye began their journey, there were no human beings. We were yet to evolve. You are seeing an almost inconceivable distance and looking back in time through 2.5m years.

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