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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 ...
The control of fire by early humans was a critical technology enabling the evolution of humans. Fire provided a source of warmth and lighting, protection from predators (especially at night), a way to create more advanced hunting tools, and a method for cooking food. These cultural advances allowed human geographic dispersal, cultural ...
A burning candle. Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. [1] [a] At a certain point in the combustion reaction, called the ignition point, flames are produced.
Flames of charcoal. A flame (from Latin flamma) is the visible, gaseous part of a fire.It is caused by a highly exothermic chemical reaction made in a thin zone. [1] When flames are hot enough to have ionized gaseous components of sufficient density, they are then considered plasma.
Deep space is defined by the United States government as all of outer space which lies further from Earth than a typical low-Earth-orbit, thus assigning the Moon to deep-space. [117] Other definitions vary the starting point of deep-space from, "That which lies beyond the orbit of the moon," to "That which lies beyond the farthest reaches of ...
View of the night sky in July The day's blue sky, clouds and the Moon. The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space. In the field of astronomy, the sky is also called the ...
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Illustration of St. Elmo's fire on a ship at sea Electrostatic discharge flashes across the windscreen of a KC-10 cockpit.. St. Elmo's fire (also called witchfire or witch's fire [1]) is a weather phenomenon in which luminous plasma is created by a corona discharge from a rod-like object such as a mast, spire, chimney, or animal horn [2] in an atmospheric electric field.