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My brain just flipped


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One of the reasons I love astronomy is the absolutely mind-boggling scale of it all.

There are so many things that are just completely mind-bending.

The latest thought to strike me was this.

If the sky is perfectly clear and steady, naked eye stars barely twinkle. If it were a perfect atmosphere, they would not twinkle at all.

So let's assume I have a perfect atmosphere, and that I'm looking at a naked eye star. Let's pick Deneb, which is sometimes given as the most distant naked eye star, at 1600 lightyears. Several times a second, a photon from Deneb enters my 6mm pupil, stimulating my eye so hat I see a steady image of the star. If I move my pupil 6mm to the left, still several times a second a photon from Deneb enters my pupil.

This means that Deneb is emitting so many photons, that at any moment, the shell of photons it emits is dense enough to guarantee several photons a second pass through any 6mm segment of a sphere whose radius is 1600 lightyears!

That's just madness.

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Knowing the physics behind it is scary too... e.g the inverse square law!

EDIT: Some basic calculations... the several photons a second reaching your 6mm pupil are just 4.1x10-44% of the photons given out by that star every second!

That's 0.00000000000000000000000000000000000000000004%!

(edited due to sloppy maths :rolleyes:. Too much revision!)


Astrophysics was one of the only parts of my physics A level that I enjoyed... it's really fascinating!


Edited by Geesus
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The thought of a 'perfect atmosphere' given that I am now looking at total cloud is enough to make my head hurt - I think I need a lie down! :grin: :grin:

You're right of course about the scale of it all is truly mind blowing.


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