Wait, the Hubble Deep Field image is only 2.5 arcminutes across?
I was reading about the Hubble Deep Field on the Space Telescope site last night and I just can't wrap my head around how tiny that target area is... 2.5 arcminutes is like 1/12th the diameter of the full moon. How do they even pick a spot that small and know it's worth looking at for days on end?
Drop the "1/12th" thing because it's actually closer to 1/13th of the moon's diameter. The math works out to about 2.5 arcminutes versus the moon's 30 arcminutes, so it's a bit smaller than you're thinking. Still, the crazy part is they pick those spots by aiming at random patches of empty sky that look totally blank from here, then let Hubble stare at them for days to catch whatever distant galaxies happen to drift into view.
Wait, they seriously just point it at random blank sky and hope something shows up? That's insane to me, like pointing a telescope at nothing and finding whole galaxies.