You just draw two lines from a single point near you with one line going to one
edge of the object and another line going to the another edge and measure the
angle between those lines. The two edges should be points on the object that
are furthest away from each other if you want to get the maximum size of the
From: az-observing-bounce@xxxxxxxxxxxxx <az-observing-bounce@xxxxxxxxxxxxx> on
behalf of Michael McDonald <mikemac@xxxxxxxxxxx>
Sent: Tuesday, August 28, 2018 3:11:41 PM
Subject: [AZ-Observing] Re: need an optics expert
Id say the trivial answer is diverging at 360 degrees.
If youre referring only to the light rays that hit your pupil, Id say theyre
CONVERGING at a VERY shallow angle given the diameter of your pupil is much
smaller than the diameter of the distant object. The extremely large distance
between your pupil and the object makes the rays nearly parallel. Its the lens
in your eye that takes those parallel light rays and focuses them, giving them
the apparent size of 1 arc second.
But since its been 40 years since I had optics in college, Im probably
missing something. And I too find I can chase my own tail on this one!
On Aug 28, 2018, at 2:33 PM, Dan Heim <dan@xxxxxxxxxxxxx> wrote:
Been puzzling about this question for some time now, and figure somebody
here should be able to answer. Question: If a distant object has an
angular size of 1 arcsecond, does that mean the rays of light from that
object are diverging at an angle of 1 arcsecond? My first intuition said
"yes" but then I started second-guessing myself. Thanks for any
clarification. -Dan Heim
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