The phenomenon you describe, where stars are not easily visible in images taken from space, is due to a combination of factors related to photography and the nature of the space environment. Here are a few reasons why stars may not appear in such images:
Exposure Settings: In space photography, cameras are often set to capture well-lit objects or scenes, such as astronauts, spacecraft, or planetary surfaces. These settings are optimized for capturing bright objects, which may cause the camera to use shorter exposure times or smaller apertures, resulting in the stars appearing faint or not captured at all. This is similar to how you adjust your camera settings on Earth to capture well-lit subjects, which can lead to dim stars or no stars appearing in photographs.
Contrast and Dynamic Range: Space environments, especially those closer to Earth, can have significant variations in brightness. Astronauts and spacecraft surfaces are highly reflective, creating a stark contrast with the darkness of space. When photographs are taken to capture these brighter subjects, the camera's dynamic range may not be sufficient to capture both the bright foreground and the relatively dim stars in the background.
Noise and Image Processing: To enhance the quality of images taken from space, various image processing techniques are applied. These processes often involve noise reduction and contrast adjustments, which can inadvertently diminish the visibility of stars, especially if they were already faint in the original image. These techniques aim to improve the visibility of the main subjects of interest, such as Earth's surface or specific astronomical features.
Light Pollution: While space itself is a vacuum devoid of atmospheric interference, space missions near Earth can still be affected by light pollution. The presence of nearby illuminated objects, such as the Earth, the Moon, or the spacecraft itself, can create a background glow that makes it difficult to capture the faint light of distant stars.
It's worth noting that there are images taken from space, particularly from deep space missions or telescopes specifically designed for astronomical observations, that do capture stars in all their glory. These images are often carefully planned and processed to optimize the visibility of stars and other celestial objects.
In summary, the absence of visible stars in many images taken from space is primarily due to the exposure settings, contrast, dynamic range, noise reduction, and image processing techniques employed, as well as the presence of bright foreground objects and potential light pollution in the vicinity.