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Q & A: vision limits

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Most recent answer: 09/30/2018
Q:
On Wikipedia it says that 20/20 vision limit is about objects with angular diameter of 1 arcsecond. However, every star other than the Sun has an angular diameter in the milliarcsecond range, far below what 20/20 would be able to see, yet we still see them. Why?
- Anonymous
A:

That limit is on your ability too resolve the actual size and shape of the object. If enough light comes from it, you'll see the light even if you can't make out the shape of the source.

Mike W.


(published on 09/24/2018)

Follow-Up #1: seeing very small bright objects

Q:
So if I understand correctly, it is not about angular size but rather about apparent magnitude that makes celestial bodies visible to the unaided eye. Does it mean we could clearly see an object that has an angular size in the microarcsecond if it had an apparent magnitude of -20 for example?
- Anonymous
A:

Yes.

Mike W.


(published on 09/30/2018)

Follow-up on this answer.