Ad Astra Observatory

http://xkcd.org/1276/

I believe the most interesting object on the page is “Betelgeuse”.
Note that Betelgeuse is 643 light years away (that’s 643 * 6 trillion miles), but is so big (if it were our sun, its radius would reach Jupiter), that it still subtends .05 arc seconds in our sky. It was the first star (other than the Sun) to have its photosphere measured.

And that’s why it’s interesting that it appears in the “ping pong table” graphic, and not the “laptop” graphic (where most of the objects are stars).

Note how important distance is to this graphic; the moon (which is 1/4 the size of the Earth) subtends 30 arcmin (half a degree) in the sky, where Jupiter (which is 300x the size of the Earth) only subtends a bit under 1 arcmin. That’s because the moon is 240 K miles, and Jupiter is 500 M miles, away.

Thank you, xkcd, for yet another awesome infographic!