What does the phrase "passive night vision" mean?

The phrase "passive night vision" refers to the capability of utilizing ambient light sources, such as moonlight or starlight, to enhance visibility in low-light conditions without emitting any light of its own. This type of vision relies on the natural light that exists in the environment to illuminate the surroundings, making it possible for a viewer to detect objects in darkness by amplifying these minimal illumination levels.

Unlike active systems, which might rely on a light source to illuminate the area, passive night vision technology enhances the available light rather than creating new light. This feature is particularly advantageous for stealth operations, as it allows users to observe without giving away their position. Therefore, the correct understanding of passive night vision focuses on its ability to work with existing light and maintain a low profile.