How do we get other pictures of far away galaxies that we can not see?
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Light is made of photons. Think of photons like golf balls being fired in every direction by stars very far away. Light works much like the golf balls, spreading out as they travel. This is why light gets dimmer the further away the source is, as the photons spread out and less hit your eyes. Eventually, there are so few photons hitting your eye that your retina can no longer detect them.
Telescopes work by gathering up a larger area of photons and then focusing them down so they’re concentrated enough to see. Think of this like a big funnel gathering up the golf balls and funneling them into a more narrow stream. To get images of far away galaxies, we have many telescopes gathering many, many photons and gathering them over an extended period. This is called “long exposure,” and it allows us to get much clearer pictures of objects that would otherwise be too dim to see clearly.
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