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Angular diameter: the angle subtended by an object
The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens). The angular diameter can alternatively be thought of as the angular displacement through which an eye or camera must rotate to look from one side of an apparent circle to the opposite side. Humans can resolve with their naked eyes diameters down to about 1 arcminute (approximately 0.017° or 0.0003 radians).[1] This corresponds to 0.3 m at a 1 km distance, or to perceiving Venus as a disk under optimal conditions.
^Yanoff, Myron; Duker, Jay S. (2009). Ophthalmology 3rd Edition. MOSBY Elsevier. p. 54. ISBN 978-0444511416.
The angulardiameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a...
In astronomy, angulardiameter distance is a distance defined in terms of an object's physical size, x {\displaystyle x} , and its angular size, θ {\displaystyle...
the galaxy and its estimated distance, leading to an angulardiameter (also called "metric diameter"). This type of measurement is subject to two significant...
extrasolar star whose photosphere's angular size was measured in 1920, and subsequent studies have reported an angulardiameter (i.e., apparent size) ranging...
dominated by diffraction. In that case, the angular resolution of an optical system can be estimated (from the diameter of the aperture and the wavelength of...
relating the diameter to the radius. Angulardiameter – How large a sphere or circle appears Caliper, micrometer, tools for measuring diameters Conjugate...
the diameter is 51.18±2.24 mas. The angulardiameter of R Doradus is larger than any other measured star other than the Sun. The angulardiameter of the...
the transverse comoving distance the "angular size distance", which is not to be mistaken for the angulardiameter distance. Occasionally, the symbols χ...
magnetic fields of stars List of directly imaged exoplanets Angular resolution Angulardiameter List of nearest stars and brown dwarfs H.Uitenbroek; Dupree...
size is R Doradus, with an angulardiameter of only 0.057 arcseconds. The disks of most stars are much too small in angular size to be observed with current...
describe small astronomical angles such as the angulardiameters of planets (e.g. the angulardiameter of Venus which varies between 10″ and 60″); the...
vein Angular (web framework), an open-source web platform AngularJS, the first incarnation of Angular Angle, having an angle or angles Angulardiameter, describing...
from Earth. The change in angulardiameter of the Sun with distance is illustrated in the diagram below: The angulardiameter of a circle whose plane is...
in the constellation Taurus. It is a semiregular variable and its angulardiameter has been measured at about 10 mas. It is a similar star to Betelgeuse...
thousands of R☉, comparable to some of the largest known black holes. The angulardiameters of stars can be measured directly using stellar interferometry. Other...
celestial object in Earth's night sky. This is mainly due to its large angulardiameter, while the reflectance of the lunar surface is comparable to that of...
its angulardiameter as large as possible). Earth being very near aphelion (furthest away from the Sun in its elliptical orbit, making its angular diameter...
the disk's radius. If instead the disk rotates about its diameter (e.g. coin toss), its angular momentum L {\displaystyle L} is given by L = 1 2 π M f r...
Nebula, the brightest nebula in the sky and occupying an area twice the angulardiameter of the full Moon, can be viewed with the naked eye but was missed by...
the cosmic distance ladder. The relation between the angulardiameter, θ, actual (physical) diameter, r, and distance, D, of an object from the observer...
Cassiopeiae's angulardiameter was measured in 1998 at various wavelengths ranging from 500 to 850 nm. The result was a limb darkened angular measurement...
measurements of the radius at infrared (K-band = 2.2 µm) wavelength gave an angulardiameter of 18.7±0.5 mas, corresponding to radii above 3,000 R☉ (2.1×109 km;...
of 4 Vesta, which will transits the Sun on January 4, 2044, with an angulardiameter of 0.24″. From the perspective of Earth, the only types of asteroids...
Angular distance or angular separation is the measure of the angle between the orientation of two straight lines, rays, or vectors in three-dimensional...
proximity to Earth, its angulardiameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it...
in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. It is defined such that one...
approximate angulardiameter of the universe and the physical size of the particle horizon that had existed at this time. The angulardiameter distance,...
characterized by the angulardiameter of the long-exposure image of a star (seeing disk) or by the Fried parameter r0. The diameter of the seeing disk is...
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