scott wrote:

> For my sun radius calculation I used the values from wikipeda, distance 
> to sun is 1.5e8 and radius of the sun is 6.96e5, dividing those two 
> gives the 214.8.

Yes, that is the correct value known since antiquity (the ratio is
simply the sine of the apparent angle that is readily observable). It
was the figuring out the actual distances/ radii that took longer ;)

http://en.wikipedia.org/wiki/Aristarchus_of_Samos

Regarding the Sun at least we rarely see the actual disk as it is lost
in the glare, and this has a larger size. And at sunset when we see it
we perceive it as larger than we would overhead:

Overhead, we tend to assume an object is not so far away (maybe typical
cloud distance). On the horizon an object is perceived to be very far
away. So the same angular size is interpreted as a larger object. This
effect persists even when no objects are available for comparison, so
that often heard explanation is an urban myth.

> IMO it also depends heavily on the angle/focal length of the camera you 
> are using, you can easily make the sun or moon look way too big or way 
> too small (IRL and in POV). 

The thing here is that the angular size of the sun is fixed, but the
angular size of other objects in the scene depends on the distance. And
in a photo or render the distance is not readily apparent, we need to
estimate it from the scale of objects.

As an extreme example suppose you simulate a telescopic view with angle
1 degree on a house on the horizon. Now the image contains a house of
reasonable size with a sun filling half the image behind it, so it looks
way to big. But if we were smarter we would judge scale from the Sun and
conclude the house is either a tiny model or very far away).

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