yönäkymän

Yönäkymä, often translated as night vision, refers to the ability of an animal or human to see in low-light conditions. This remarkable capability is achieved through specialized biological adaptations that enhance the detection of light and its interpretation by the brain.

In animals, particularly nocturnal species, a primary adaptation is the presence of a higher proportion of rods in their retinas compared to cones. Rods are photoreceptor cells highly sensitive to light but do not perceive color. This allows them to detect even faint light sources, such as moonlight or starlight. Many animals also possess a tapetum lucidum, a reflective layer behind the retina that bounces light back through the photoreceptors, effectively giving them a second chance to absorb available photons. This is what causes the "eyeshine" observed when light reflects from the eyes of certain animals in the dark.

Human night vision, while less acute than that of many nocturnal animals, also relies on the rods in the retina. Prolonged exposure to darkness allows the rod cells to become more sensitive, a process known as dark adaptation. Specialized electronic devices, known as night vision goggles or scopes, mimic and amplify these natural processes. They typically use image intensification to amplify ambient light or thermal imaging to detect heat signatures, enabling vision in conditions where natural light is insufficient.