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A coronagraph is a telescopic attachment designed to block out the direct light from a star or other bright object so that nearby objects – which otherwise would be hidden in the object's bright glare – can be resolved. Most coronagraphs are intended to view the corona of the Sun, but a new class of conceptually similar instruments (called stellar coronagraphs to distinguish them from solar coronagraphs) are being used to find extrasolar planets and circumstellar disks around nearby stars as well as host galaxies in quasars and other similar objects with active galactic nuclei (AGN). Invention The coronagraph was introduced in 1931 by the French astronomer Bernard Lyot; since then, coronagraphs have been used at many solar observatories. Coronagraphs operating within Earth's atmosphere suffer from scattered light in the sky itself, due primarily to Rayleigh scattering of sunlight in the upper atmosphere. At view angles close to the Sun, the sky is much brighter than the background corona even at high altitude sites on clear, dry days. Ground-based coronagraphs, such as the High Altitude Observatory's Mark IV Coronagraph...

The Eurasian griffon vulture (Gyps fulvus) is a large Old World vulture in the bird of prey family Accipitridae. It may also be known as the Griffon vulture, though it may be used for the genus as a whole. It is not to be confused with the Rüppell's griffon vulture (Gyps rueppellii) and Himalayan griffon vulture (Gyps himalayensis). It is closely related to the white-backed vulture (Gyps africanus). Description The griffon vulture is 93–122 cm (37–48 in) long with a 2.3–2.8 m (7.5–9.2 ft) wingspan. In the nominate race the males weigh 6.2 to 10.5 kg (14 to 23 lb) and females typically weigh 6.5 to 10.5 kg (14 to 23 lb), while in the Indian subspecies (G. f. fulvescens), the vultures average 7.1 kg (16 lb). Extreme adult weights have been reported from 4.5 to 15 kg (9.9 to 33.1 lb), the latter likely a weight attained in captivity. Hatched naked, it is a typical Old World vulture in appearance, with a very white head, very broad wings and short tail feathers. It has a white neck ruff and yellow bill. The buff body and wing coverts contrast with the...