4 votes out of about 400 views. That's at least as good as the turnout for the US presidential elections, so it must be time for the answer!
OK,
You need to start up Celestia and then make the window very small, about this size will do:
Go to Chuft-Captain's "Orion docking at Space Station V" page:
http://traitorsclaw.sitesled.com/downloads.html and click on the
Inside Docking Bay URL.
Now you'll see this:
Hold down Celestia's "zoom out" key (.) until it zooms out to the maximum you can get to (should be about 120 deg)
Now, grab the top right corner of the Celestia window with your mouse and drag it to make it larger. You will notice some strange effects as you do this, but keep your eyes on the FOV display at the bottom right. Keep going until the FOV display shows just over 180 degrees.
If you can stop very close to 180 degs you may be lucky enough to get the second effect (sun going Nova), at 181 degrees, you'll probably get something like the first effect.
That's all there is to it. Have fun!
Congrats to
jgrillo2002 for his "very high FOV" guess.
Actually, it's more of a bug than anything else (although some might consider it a feature.

)