Sharpness is the great lie of giant ground telescopes. Their mirrors look dominant on paper, yet a modest observatory in orbit often wins the image. The reason starts with the air itself: every column of atmosphere acts like boiling glass, its constantly shifting pockets of temperature and density bending starlight and smearing fine detail that the mirror could, in theory, resolve by the simple diffraction limit.
Deeper views, too, belong to orbit. Turbulence is only half the penalty; air also glows. Molecules emit and absorb in optical and infrared bands, adding a hazy background that swamps the faintest galaxies long before a detector hits its noise floor. Space telescopes operate in vacuum, where that sky brightness collapses, so long exposures can stack uncorrupted photons until signals thousands of times dimmer than the night sky on Earth emerge clean.
Ground observatories fight back with adaptive optics, using deformable mirrors and rapid wavefront sensing to claw back angular resolution over small patches of sky, but the fix is partial and fragile. Some wavelengths, especially much of the infrared and ultraviolet, never reach the surface at all because of atmospheric absorption bands. In space, no such filter sits overhead, so even a smaller mirror, free of blur, glow, and missing frequencies, becomes the more powerful eye.
