Knowra Airglow Airglow Airglow is faint light emitted by a planet’s upper atmosphere through chemical reactions, sunlight-driven processes, and interactions with charged particles. It persists at night as well as during daylight.
Chemiluminescence : Light produced by a chemical reaction without requiring high temperature. Reactions between atmospheric atoms and molecules release energy as airglow photons.
Upper atmosphere : The high-altitude atmospheric region above the lower atmosphere, including the mesosphere, thermosphere, and ionosphere. Airglow originates in this rarefied region, where collisions and sunlight drive emission.
Night-sky brightness : The total diffuse light in the night sky, including natural and artificial sources. Airglow is a major natural component that limits the darkness of astronomical observations.
Aurora : A luminous atmospheric display caused chiefly by energetic charged particles guided by a planet’s magnetic field. Unlike ordinary airglow, aurora is commonly concentrated into bright forms near magnetic polar regions.
Recombination (physics) : The process in which a free electron combines with an ion, often releasing energy as light. It produces prominent emissions when ionized atmospheric particles reunite after sunset.
Mesosphere : The atmospheric layer above the stratosphere and below the thermosphere. Several strong airglow bands form near the mesopause, at the mesosphere’s upper boundary.
Ground-based astronomy : Astronomical observation conducted with instruments on Earth’s surface. Airglow contaminates faint observations, while its predictable emission lines can aid calibration.
Zodiacal light : Sunlight scattered by interplanetary dust, appearing as a diffuse glow along the ecliptic. It is sunlight scattered in space, not light emitted by a planet’s atmosphere.
Resonance fluorescence : Light emitted when an atom absorbs and re-emits radiation at characteristic wavelengths. Sunlight excites atmospheric atoms whose re-emission contributes to daytime airglow.
Thermosphere : The atmospheric layer in which temperature rises sharply with altitude as gases absorb energetic solar radiation. Its excited atoms and ions produce prominent visible and ultraviolet airglow.
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