Twilight

Twilight is a natural phenomenon that occurs twice a day, during the periods of time when the Sun is below the horizon but its light is still visible due to atmospheric refraction. This phenomenon is divided into three stages: civil twilight, nautical twilight, and astronomical twilight.

Civil Twilight

Civil twilight is the brightest form of twilight. It begins in the morning when the geometric center of the Sun is 6 degrees below the horizon and ends at sunrise. In the evening, it starts at sunset and ends when the Sun reaches 6 degrees below the horizon.

Nautical Twilight

Nautical twilight is the second stage of twilight. It begins in the morning and ends in the evening when the geometric center of the Sun is between 6 and 12 degrees below the horizon. During this time, sailors can take reliable readings of stars, hence the name.

Astronomical Twilight

Astronomical twilight is the darkest stage of twilight. It occurs when the geometric center of the Sun is between 12 and 18 degrees below the horizon. During this time, the faintest stars become visible in the absence of moonlight or atmospheric interference.

Cultural Significance

Twilight has been a source of inspiration in various cultures and arts. It is often associated with romance, mystery, and melancholy. Many artists, writers, and filmmakers have used twilight as a backdrop for their works.

See Also

• Dawn
• Dusk
• Golden hour (photography)
• Blue hour

Twilight Resources
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