Not true, atmosphere range is dependent on composition, gravity and volume/density. A lot of low trajectory orbit satelites are within atmosphere, Also space is not empty, Earth even in relatively clean space picks up tonnes of cosmic dust each year, there is no reason we cant be much near a nebula (which is like a city smog bubble unnoticeable while on inside). Also if door just opened atmosphere in airlock had just been vented to equalise pressure and all the water in air would have frozen instantly.
That is light from within, probably the airlock that opened.