Eli5 Why aren’t stars blurry

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That’s kind of the wrong question. I’m not exactly sure how to ask because I don’t know where I’m confused.

This morning, sitting under the stars for 2 hours before sunrise, I pondered the old light of stars.I had never thought about the journey light had to travel and retain its form. I don’t understand how we see the source as a pin prick of light from that distance… and someone standing right next to you (or half way across the earth) would see the same pin prick but it would be different photons hitting their retinas.

How does the light spread like that but retain any form? If photons move perceptibly (to our measuring equipment) in close distances in the double slit experiment, how do they stay in a tight enough formation over those vast distances to still look like a pin prick when they reach us. I’m not sure I’m asking the right question but I found my mind a little boggled by what is probably a simple to explain phenomenon that shouldn’t even be confusing. Probably a couple questions in there.

Thanks!

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6 Answers

Anonymous 0 Comments

The reason is you have a lens in front of your retina that focuses the light. All light that comes from one direction will be focused from the same point.

If your eye did not have a lens light from the star would hit all of it just like light from any other object. Start are not special they are just very far away from light sources.

Take a paper out in sunlight and you see all of it getting illuminated. I you have a lens that can focus the light on the paper the sun will just be a small but bright area that might deliver enough energy to ignite the paper.

Here is an example of it being done with binoculars [https://www.youtube.com/watch?v=fCnZlH4-6Go](https://www.youtube.com/watch?v=fCnZlH4-6Go) your eye do the same thing.

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