No chromatic aberration. Faint objects only seen with BIG objective telescopes. The wavelength and diameter must be measured in the same length units. The atmosphere will usually smear images so this theoretical resolving power not reached with telescopes on ground. Speckle interferometry can get rid of atmospheric distortion.
Adaptive optics is another way to remove atmospheric distortion.
The air is in turbulent motion and light from celestial objects is bent randomly in many ways over time periods of tens of milliseconds. This atmospheric effect is called seeing. Good seeing is when the air is stable and the twinkling is small. The air also absorbs and scatters different wavelengths in different amounts. Redder light is scattered less by atmosphere molecules and dust than bluer light.