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Photometric system. In astronomy, a photometric system is a set of well-defined passbands (or optical filters ), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.
Rayleigh scattering causes the blue color of the daytime sky and the reddening of the Sun at sunset. Rayleigh scattering (/ ˈ r eɪ l i / RAY-lee), named after the 19th-century British physicist Lord Rayleigh (John William Strutt), is the predominantly elastic scattering of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation.
The blue sky spectrum contains light at all visible wavelengths with a broad maximum around 450–485 nm, the wavelengths of the color blue. Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules or particulates in the atmosphere. It is also called sky radiation ...
e. In heraldry, a bend is a band or strap running from the upper dexter (the bearer's right side and the viewer's left) corner of the shield to the lower sinister (the bearer's left side, and the viewer's right). Authorities differ as to how much of the field it should cover, ranging from one-fifth (if shown between other charges) up to one ...
A measure of the brightness of a celestial body as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere. The brighter the object appears, the lower its magnitude. appulse. The closest approach of one celestial object to another, as viewed from a third body.
Brian Eno. " Bullet the Blue Sky " is a song by Irish rock band U2, and is the fourth track from their 1987 album The Joshua Tree. Lyrically, the song was inspired by a trip that lead vocalist Bono made to Nicaragua and El Salvador, where he saw firsthand how local peasants were affected by United States military intervention in the region.
The blue colour of the sky is a direct result of Rayleigh scattering which redirects higher frequency (blue) sunlight back into the field of view of the observer. Because blue light is scattered more easily than red light, the sun takes on a reddish hue when it is observed through a thick atmosphere, as during a sunrise or sunset. Additional ...
Particles in the air scatter short-wavelength light (blue and green) through Rayleigh scattering much more strongly than longer-wavelength yellow and red light. Loosely, the term crepuscular rays is sometimes extended to the general phenomenon of rays of sunlight that appear to converge at a point in the sky, irrespective of time of day.