Great post about size...

[szymon]

I thought this was superb.

http://www.ba-bamail.com//view.aspx?emailid=12288&MemberId=0&&

I wonder what kind of magnitude our sun would be if looking from say Arcturus...

[DirkSteele]

That is pretty easy to answer actually.  There is a simple relationship that governs apparent magnitude (how bright an object appears in the sky) to absolute magnitude (how bright the object is at a distance of 10 parsecs).  The absolute magnitude of the Sun is +4.83.  Arcturus is 11.2 parsecs from us.

The relationship is

m = M – 5* (1-Log₁₀ d)

where m is apparent magnitude

M is absolute magnitude

d is distance in parsecs

Input all our numbers and the Sun would appear to be +5.07, so in a light polluted sky you would barely see it.

Nice post of the relative sizes.  Really brings it home.

[Ruud]

If you like this sort of thing you should download Celestia. Chose Navigation>Goto and type in Arcturus. Press enter. You'll fly to Arcturus.

Press the H-key to follow the Sun. H stands for home. You'll see that while you're at Arcturus, the Sun is 36.718 light years away and that it has magnitude 5.09.

In Celestia you can go anywhere and look wherever you like. This screenshot from Wikipedia has us on one of the moons of Jupiter looking at Io. Europa is in the view as well 

Form the Celestia Motherlode you can download different objects (or different resolution textures for them). You can even download complete fantasy solar systems, with planets, moons, even space stations.

It's nice to park yourself over a pole of Saturn and track it while it orbits the Sun in condensed time. Or to go into a synchronous orbit of Titan and study Saturn from there.

Enjoy