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  2. Angular diameter - Wikipedia

    en.wikipedia.org/wiki/Angular_diameter

    The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) 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 ).

  3. Visual angle - Wikipedia

    en.wikipedia.org/wiki/Visual_angle

    The observers in experiment carried out by Murray and colleagues viewed a flat picture with two discs that subtended the same visual angle and formed retinal images of the same size , but the perceived angular size ′ of one was about 17% larger than for the other, due to differences in the background patterns for the disks. It was shown that ...

  4. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    Optical diameter of Betelgeuse: 1.4 Tm Orbital distance of Saturn from Sun 2 Tm Estimated optical diameter of VY Canis Majoris, one of the largest-known stars: 5.9 Tm Orbital distance of Pluto from the Sun ~ 7.5 Tm Outer boundary of the Kuiper belt: 10 13: 10 Tm: Diameter of the Solar System as a whole [1] 16.09 Tm

  5. Numerical aperture - Wikipedia

    en.wikipedia.org/wiki/Numerical_aperture

    Instead, the angular aperture of a lens (or an imaging mirror) is expressed by the f-number, written f /N, where N is the f-number given by the ratio of the focal length f to the diameter of the entrance pupil D: =. This ratio is related to the image-space numerical aperture when the lens is focused at infinity. [3]

  6. Angular resolution - Wikipedia

    en.wikipedia.org/wiki/Angular_resolution

    In that case, the angular resolution of an optical system can be estimated (from the diameter of the aperture and the wavelength of the light) by the Rayleigh criterion defined by Lord Rayleigh: two point sources are regarded as just resolved when the principal diffraction maximum (center) of the Airy disk of one image coincides with the first ...

  7. File:Comparison angular diameter.svg - Wikipedia

    en.wikipedia.org/wiki/File:Comparison_angular...

    Comparison of angular diameter of some celestial bodies: Image title: Comparison of angular diameter of the Sun, Moon and planets, compiled by CMG Lee. To get a true representation of the sizes, view the image at a distance of 103 [1 / tan(33.5/60 * pi/180)] times the width of the largest (Moon: max.) circle.

  8. Texas wants to buy surplus border wall parts but U.S ... - AOL

    www.aol.com/texas-wants-buy-surplus-border...

    Texas officials try to intercept sale of surplus border wall materials Patrick noted that Texas became aware of the materials slated for auction on Dec. 12, the same day the Daily Wire reported ...

  9. Sparrow's resolution limit - Wikipedia

    en.wikipedia.org/wiki/Sparrow's_resolution_limit

    The angular diameter of the Airy disk is determined by the aperture of the instrument. Rayleigh's resolution limit is reached when the two stars are separated by the theoretical radius of the first dark interval around the Airy disk, which is larger than the disk's apparent radius, so that a distinct dark gap appears between the two disks.