Ufo

Ufo

(alt-text)

"It's a little low for a weather balloon; it might be some other kind." "Yeah. Besides, I know I'm the alien conspiracy guy, but come on--the idea that the government would care about hiding something so mundane as atmospheric temperature measurement is too ridiculous even for me."

What If? is now on YouTube!
Check out the first video for the answer to
“What if we aimed the Hubble Telescope at Earth?”
and follow xkcd’s What If? The Video Series channel to be notified about each new video.