Shadows in space aren't, in general, any sharper than on Earth. The "penumbra" of a shadow -- the blurry, partially-shaded region -- is basically a simple geome

Shadows in space aren't, in general, any sharper than on Earth. The "penumbra" of a shadow -- the blurry, partially-shaded region -- is basically a simple geometric effect, caused by the light source being partially obscured. The penumbra's size is approximately equal to the product of the light source's angular size and the distance from the shadow-casting object to the illuminated surface. (Diffraction has some effect as well, but only on very small scales that aren't particularly relevant here.) The sun has almost exactly the same apparent angular size from either Earth's surface or LEO, because it's almost exactly the same distance away. But since that angular size is only about half a degree, shadows observed at short distances appear fairly sharp, either on Earth or in space. What you may be thinking of is that, in many cases, shadows are darker in space, because the sky is dark, even in broad daylight. There's no atmospheric scattering to provide indirect, ambient illumination of regions that are shaded from direct sunlight. But there can still be indirect lighting from other surfaces. For example, in photos of Apollo astronauts on the moon, shaded regions of the astronauts' spacesuits are still fairly-well illuminated by light bouncing off the lunar surface. But shadowed regions of the surface itself appear almost pitch-black, because the only thing they can "see" is the dark sky.