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The main source of natural light on Earth is the Sun. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development of electric lights and power systems, electric lighting has effectively replaced firelight.
This is a list of sources of light, the visible part of the electromagnetic spectrum.Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic energy, and include light bulbs and stars like the Sun. Reflectors (such as the moon, cat's eyes, and mirrors) do not actually produce the light that ...
In this experiment, humans were in an underground, sound-proof bunker where the lights were continuously on. The subjects prepared their own meals and took their own samples, so there were no social interaction cues either. Humans therefore adjust from 24.9 hr internal rhythm to the 24-hour day.
A natural phenomenon is an observable event which is not man-made. Examples include: sunrise, weather, fog, thunder, tornadoes; biological processes, decomposition, germination; physical processes, wave propagation, erosion; tidal flow, and natural disasters such as electromagnetic pulses, volcanic eruptions, hurricanes and earthquakes. [1] [2]
Optical phenomena encompass a broad range of events, including those caused by atmospheric optical properties, other natural occurrences, man-made effects, and interactions involving human vision (entoptic phenomena).
Earthshine – Light reflected from the Earth; Zodiacal light – Faint solar glow caused by interplanetary dust at sunset and sunrise; Gegenschein – Optical effect of interplanetary dust reflections; Reflection nebula – Clouds of interstellar dust which reflect the light of nearby stars
Artificial sunlight is useful in treating and preventing seasonal affective disorder (also known as winter depression, which causes depression symptoms specifically in winter), [3] and delayed sleep phase syndrome, in which the circadian rhythm (the rhythmic alternation between daylight and nighttime behavior and bodily states) is disturbed and the person falls asleep much later than he or she ...
The existence of nearly all life on Earth is fueled by light from the Sun. Most autotrophs, such as plants, use the energy of sunlight, combined with carbon dioxide and water, to produce simple sugars—a process known as photosynthesis. These sugars are then used as building-blocks and in other synthetic pathways that allow the organism to grow.