Dawn and dusk are two brief yet beautiful moments in a day. In fact, not everyone fully understands these concepts and the differences between them. The article below will provide you with the simplest and most comprehensible definitions of dawn and dusk. Let’s take a look.
What is Dawn?
Dawn, or daybreak, occurs just before the Sun rises. It is characterized by the presence of faint rays of light from the Sun while the Sun is still below the horizon.
Dawn at Cua Lo, Vietnam.
Classification
- Astronomical Dawn: This is the period calculated from the moment when the sky is no longer completely dark, officially defined as the time when the Sun is at an angle of 18 degrees below the horizon in the morning until the Sun rises. It closely aligns with the concept of astronomical dawn used in the United States.
- Nautical Dawn: This period is calculated from the moment when there is enough light from the Sun on the horizon to distinguish some objects, officially defined as when the Sun is at an angle of 12 degrees below the horizon in the morning until the Sun rises. It closely aligns with the concept of nautical dawn used in the United States.
- Civil Dawn: This period is calculated from the moment when there is sufficient sunlight to distinguish some objects and engage in outdoor activities without artificial light, officially defined as when the Sun is at an angle of 6 degrees below the horizon in the morning until the Sun rises. It closely aligns with the concept of civil dawn used in the United States.
Dawn should not be confused with sunrise, which is the moment when the upper edge of the Sun appears above the horizon.
What is Dusk?
A sunset scene.
Dusk, also known as twilight, gloaming, or dusk light, refers to the period starting right after sunset until it is completely dark (evening). It is a concept linked to the apparent position of the Sun below the horizon.
Classification
- Astronomical Dusk: This is the time when the Sun is between 12 to 18 degrees below the horizon in the evening. During this time, the Sun no longer illuminates the sky, thus it does not interfere with astronomical observations.
- Nautical Dusk: This is the time when the Sun is between 6 to 12 degrees below the horizon in the evening. At this time, objects can no longer be distinguished, and the horizon is no longer visible to the naked eye.
- Civil Dusk: This is the period when the Sun is between 0 to 6 degrees below the horizon in the evening. During this time, objects can still be distinguished, and some stars (including certain fixed stars and some planets of the Solar System) become visible in the sky when conditions are clear.
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