Hi there! Can someone please explain how this effect was achieved? I can normally key out a sky as long as nothing else in the picture is the same color as the sky, but this was obviously shot at night and everything has black in it, yet they only took out the sky and replaced it with the planets ect. How is this possible? can it be done through after effects?
Color is one parameters that can be keyed and Luminance is another. This is called high-contrast matte. The extract effect is good for this type of work. also, We don't know how the original shot was captured. It's possible that this video had much more information than we can see in the final result.
Or it could just be rotoscoped
Did you ever solve this issue? If so, how? Did you use a high contrast matte? Please let us know if any of these answers helped you solve your issue and can be marked as correct.