[avereveard]

these materials are transparent to light it is not a property of the human vision system that light goes trough N2

[7jjjjjjj]

These materials are transparent to some light. They absorb a lot of infrared and ultraviolet. The human vision system can see the light that isn't absorbed and as a result is abundant in our environment.

[inigyou]

The good news is that most stars have a spectrum very roughly similar to ours, so we can expect that aliens can probably see these wavelengths.