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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.
Skyglow (or sky glow) is the diffuse luminance of the night sky, apart from discrete light sources such as the Moon and visible individual stars. It is a commonly noticed aspect of light pollution . While usually referring to luminance arising from artificial lighting , skyglow may also involve any scattered light seen at night, including ...
Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon; [4] all values are for 10 °C and 1013.25 hPa ...
Stars in the night sky. The first star catalogue in Greek astronomy was created by Aristillus in approximately 300 BC, with the help of Timocharis. [10] The star catalog of Hipparchus (2nd century BC) included 1,020 stars, and was used to assemble Ptolemy's star catalogue. [11] Hipparchus is known for the discovery of the first recorded nova ...
The effect is well known as an illusion affecting pilots who fly at night. It is particularly dangerous for pilots flying in formation or rejoining a refueling tanker at night. Steps that can be taken to prevent or overcome the phenomenon include: Shifting your gaze frequently to avoid prolonged fixation on light sources.
In astronomy, the fixed stars (Latin: stellae fixae) are the luminary points, mainly stars, that appear not to move relative to one another against the darkness of the night sky in the background. This is in contrast to those lights visible to naked eye , namely planets and comets , that appear to move slowly among those "fixed" stars.
Aberration is related to two other phenomena, light-time correction, which is due to the motion of an observed object during the time taken by its light to reach an observer, and relativistic beaming, which is an angling of the light emitted by a moving light source. It can be considered equivalent to them but in a different inertial frame of ...
Download as PDF; Printable version; ... This is a list of M-type stars within 13 light years. ... and the fourth-brightest individual star in the night sky.