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A goose (pl.: geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera Anser (grey geese and white geese) and Branta (black geese). Some members of the Tadorninae subfamily (e.g., Egyptian goose, Orinoco goose) are commonly called geese, but are not considered "true geese" taxonomically. [1]
Betelgeuse is the brightest near-infrared source in the sky with a J band magnitude of −2.99; [95] only about 13% of the star's radiant energy is emitted as visible light. If human eyes were sensitive to radiation at all wavelengths, Betelgeuse would appear as the brightest star in the night sky.
Eurasian cranes in a V formation (video) Birds flying in V formation. A V formation is a symmetric V- or chevron-shaped flight formation.In nature, it occurs among geese, swans, ducks, and other migratory birds, improving their energy efficiency, while in human aviation, it is used mostly in military aviation, air shows, and occasionally commercial aviation.
Luminous energy per unit time Luminous intensity: I v: candela (= lumen per steradian) cd (= lm/sr) J: Luminous flux per unit solid angle: Luminance: L v: candela per square metre: cd/m 2 (= lm/(sr⋅m 2)) L −2 ⋅J: Luminous flux per unit solid angle per unit projected source area. The candela per square metre is sometimes called the nit ...
This means that for an ideal optical system, the luminance at the output is the same as the input luminance. For real, passive optical systems, the output luminance is at most equal to the input. As an example, if one uses a lens to form an image that is smaller than the source object, the luminous power is concentrated into a smaller area ...
A rainbow is a decomposition of white light into all of the spectral colors. Laser beams are monochromatic light, thereby exhibiting spectral colors. A spectral color is a color that is evoked by monochromatic light, i.e. either a spectral line with a single wavelength or frequency of light in the visible spectrum, or a relatively narrow spectral band (e.g. lasers).
What do 2 million geese sound like? Four million wings flapping, 2 million beaks honking — it’s something beyond description, officials at the Loess Bluffs National Wildlife Refuge say.
Goose breeds are usually grouped into three weight classes: Heavy, Medium and Light. Most domestic geese are descended from the greylag goose (Anser anser). The Chinese and African Geese are the domestic breeds of the swan goose (A. cygnoides); they can be recognized by their prominent bill knob. [1]