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The length of polar night varies by latitude from 24 hours just inside the polar circles to 179 days at the poles. As there are various kinds of twilight, there also exist various kinds of polar twilight that progress towards true polar night. Each kind of polar night is defined as when it is darker than the corresponding kind of twilight.
Olbers's paradox says that because the night sky is dark, at least one of these three assumptions must be false. Olbers's paradox , also known as the dark night paradox or Olbers and Cheseaux's paradox , is an argument in astrophysics and physical cosmology that says the darkness of the night sky conflicts with the assumption of an infinite and ...
Relationship of Earth's axial tilt (ε) to the tropical and polar circles. The Arctic Circle is the southernmost latitude in the Northern Hemisphere at which the centre of the Sun can remain continuously above or below the horizon for twenty-four hours; as a result, at least once each year at any location within the Arctic Circle the centre of the Sun is visible at local midnight, and at least ...
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlight , starlight , and airglow , depending on location and timing.
What is the winter solstice? The winter solstice occurs in the Northern Hemisphere on Saturday, Dec. 21. This celestial event happens when the Earth's axial tilt positions the Northern Hemisphere ...
Sky brightness refers to the visual perception of the sky and how it scatters and diffuses light. The fact that the sky is not completely dark at night is easily visible. If light sources (e.g. the Moon and light pollution ) were removed from the night sky , only direct starlight would be visible.
The Arctic tundra has historically helped reduce global emissions. But rising temperatures and wildfires in the region are changing that, scientists say. Arctic tundra becoming a source of carbon ...
One winter night on the Upper West Side, Peter, a middle-aged Irish burglar, attempts to rob a fortresslike mansion. He thinks its empty, but the millionaire's daughter, Beverly, is home—and ...