I like Padraig's answer. An optical description is: "THE OBJECT SUBTENDS AND
ANGLE OF 1 ARCSECOND AS SEEN BY THE OBSERVER." That is to say that if two
lines are drawn from obersvers eye (considered very small) to opposite edges of
the object, the angle is 1 arcsecond. Of course the object itself may radiate
in all directions, as was already said.
----- Original Message -----
From: Padraig Houlahan <pjhmx1@xxxxxxxxx>
To: az-observing@xxxxxxxxxxxxx
Sent: Tue, 28 Aug 2018 18:42:29 -0400 (EDT)
Subject: [AZ-Observing] Re: need an optics expert
It just means the angle between one edge and its opposite is 1 arcsec as seen
from Earth.
Each edge ca be radiating light in all directions but only some are directed
towards us.
Sent from my iPhone
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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