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The time of dusk is the moment at the very end of astronomical twilight, just before the minimum brightness of the night sky sets in, or may be thought of as the darkest part of evening twilight. [4] However, technically, the three stages of dusk are as follows: At civil dusk, the center of the Sun's disc goes 6° below the horizon in the ...
Twilight occurs according to the solar elevation angle θ s, which is the position of the geometric center of the Sun relative to the horizon. There are three established and widely accepted subcategories of twilight: civil twilight (nearest the horizon), nautical twilight, and astronomical twilight (farthest from the horizon).
For example, a Latinate word might enter English by way of Old French, but enter Spanish directly from Latin. Such differences can introduce changes in spelling and meaning. Although most of the cognates have at least one meaning shared by English and Spanish, they can have other meanings that are not shared.
Daylight saving time (DST) is the practice of advancing clocks during warmer months so that darkness falls later each day according to the clock.. Proponents of DST generally argue that it saves energy, promotes outdoor leisure activity in the evening (in summer), and therefore is good for physical and psychological health, reduces traffic accidents, reduces crime or is good for business.
Finally, night occurs when the Sun reaches 18 degrees below the horizon and no longer illuminates the sky. [4] Locations further north than the Arctic Circle and further south than the Antarctic Circle experience no full sunset or sunrise on at least one day of the year, when the polar day or the polar night persists continuously for 24 hours ...
The natural day (dies naturalis) ran from sunrise to sunset. [6] The hours were numbered from one to twelve as hora prima, hora secunda, hora tertia, etc. To indicate that it is a day or night hour, Romans used expressions such as for example prima diei hora (first hour of the day), and prima noctis hora (first hour of the night). [7]
Blue hour at the Old Cathedral of the Holy Name of Jesus, Bragança in Portugal. The blue hour (from French l'heure bleue; [1] [a] pronounced [lœʁ blø]) is the period of twilight (in the morning or evening, around the nautical stage) when the Sun is at a significant depth below the horizon.
Zodiacal light seen behind the Submillimeter Array from the summit of Mauna Kea. In the mid-latitudes, the zodiacal light is best observed in the western sky in the spring after the evening twilight has completely disappeared, or in the eastern sky in the autumn just before the morning twilight appears.