Question

Why can't we see stars in the sky when earth is filmed from space?

Answer 1

Depending on where the camera is, you can see stars when Earth is filmed from space.

Explanation:

When filming Earth from space, whether stars are visible will largely depend on the distance from the Earth.

First of all we need a definition of where the Earth's atmosphere finishes and outer space starts. Officially an altitude of 100km is considered the boundary between the atmosphere and outer space. In fact any satellite with a minimum altitude of less than 2000Km will experience drag from the atmosphere.

Most images of Earth come from the ISS and other satellites. The ISS is at an altitude of 400km. When close to the Earth, the planet is very bright so to take a photograph or film would require a short exposure so the features of the Earth are not burned out. In such images the stars are not bright enough to be captured. Also, Earth takes up most of the frame and stars won't be visible through the atmosphere.

If images are taken from much further away it is a different story. The images taken by the Apollo missions from space and from the Moon clearly show stars. At these larger distances the Earth isn't so bright and hence brighter stars will get captured in the image. The further away the camera is the more stars will be captured.

So images of Earth will contain stars as long as the camera is far enough away from Earth.