Noctilucent (or noctilucous) clouds are an extremely rare type of cloud, perhaps one of the rarest, that forms in very high atmospheres ( it has been observed up to 110 km altitude, so yes, in space). They are visible only a little after sunset or a little before sunrise, mainly near the poles.
We do not really understand their training at all. They could be partly extraterrestrial, that is to say to form from dust of meteorites passing in the orbit of the earth. It is also known that water vapor from rocket launchers contributes to their formations.