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  2. Asterism (gemology) - Wikipedia

    en.wikipedia.org/wiki/Asterism_(gemology)

    The star-effect may be also caused by the inclusions of hematite. In black star sapphire hematite needles formed parallel to the faces of the second order prism produce asterism. Some star sapphires from Thailand contain both hematite and rutile needles forming a 12-ray star. [3] Star-stones were formerly regarded with much superstition. [1]

  3. List of stars with resolved images - Wikipedia

    en.wikipedia.org/wiki/List_of_stars_with...

    The following is a list of stars with resolved images, that is, stars whose images have been resolved beyond a point source. Aside from the Sun , observed from Earth , stars are exceedingly small in apparent size, requiring the use of special high-resolution equipment and techniques to image.

  4. Celestial spheres - Wikipedia

    en.wikipedia.org/wiki/Celestial_spheres

    In Greek antiquity the ideas of celestial spheres and rings first appeared in the cosmology of Anaximander in the early 6th century BC. [7] In his cosmology both the Sun and Moon are circular open vents in tubular rings of fire enclosed in tubes of condensed air; these rings constitute the rims of rotating chariot-like wheels pivoting on the Earth at their centre.

  5. Rutile - Wikipedia

    en.wikipedia.org/wiki/Rutile

    Rutile is an oxide mineral composed of titanium dioxide (TiO 2), the most common natural form of TiO 2. Rarer polymorphs of TiO 2 are known, including anatase , akaogiite , and brookite . Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high ...

  6. Next solar eclipse: When and where to view the celestial event

    www.aol.com/missed-ring-fire-eclipse-where...

    The "diamond ring" effect is visible as the moon makes its final move over the sun during a total solar eclipse at Palm Cove, Australia, in November 2012. - Greg Wood/AFP/Getty Images

  7. Halo (optical phenomenon) - Wikipedia

    en.wikipedia.org/wiki/Halo_(optical_phenomenon)

    A halo (from Ancient Greek ἅλως (hálōs) 'threshing floor, disk') [1] is an optical phenomenon produced by light (typically from the Sun or Moon) interacting with ice crystals suspended in the atmosphere. Halos can have many forms, ranging from colored or white rings to arcs and spots in the sky.

  8. Corona (optical phenomenon) - Wikipedia

    en.wikipedia.org/wiki/Corona_(optical_phenomenon)

    Lunar corona A solar corona up Beinn Mhòr (South Uist). In meteorology, a corona (plural coronae) is an optical phenomenon produced by the diffraction of sunlight or moonlight (or, occasionally, bright starlight or planetlight) [1] by individual small water droplets and sometimes tiny ice crystals of a cloud or on a foggy glass surface.

  9. Diffraction spike - Wikipedia

    en.wikipedia.org/wiki/Diffraction_spike

    Effect of a triangular star filter. A cross screen filter, also known as a star filter, creates a star pattern using a very fine diffraction grating embedded in the filter, or sometimes by the use of prisms in the filter. The number of stars varies by the construction of the filter, as does the number of points each star has.