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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).
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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 ...
With a full year being slightly more than 360 days, the Earth's daily orbit around the Sun is slightly less than 1°, so the day is slightly less than 361° of rotation. Elsewhere in the Solar System or other parts of the universe, a day is a full rotation of other large astronomical objects with respect to its star. [4]
English: This is the Teacher's Guide of the "Reading Wikipedia in the Classroom" program corresponding to Module 2 in Spanish. "Reading Wikipedia in the Classroom" is a professional development program for secondary school teachers led by the Education team at the Wikimedia Foundation.
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.
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]