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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 ...
The conventional colour description takes into account only the peak of the stellar spectrum. In actuality, however, stars radiate in all parts of the spectrum. Because all spectral colours combined appear white, the actual apparent colours the human eye would observe are far lighter than the conventional colour descriptions would suggest.
The stars are caused by the light reflecting from needle-like inclusions of rutile aligned perpendicularly to the rays of the star. 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.
Lists of stars. List of nearest stars; List of brightest stars; List of hottest stars; List of nearest bright stars; List of most luminous stars; List of most massive stars; List of largest known stars; List of smallest stars; List of oldest stars; List of stars with proplyds; List of variable stars; List of semiregular variable stars; List of ...
Afterimage on empty shape (also known as color dove illusion) This type of illusion is designed to exploit graphical similarities. Ambiguous image: These are images that can form two separate pictures. For example, the image shown forms a rabbit and a duck. Ambigram: A calligraphic design that has multiple or symmetric interpretations. Ames ...
The Cat's Eye Nebula (also known as NGC 6543 and Caldwell 6) is a planetary nebula in the northern constellation of Draco, discovered by William Herschel on February 15, 1786. It was the first planetary nebula whose spectrum was investigated by the English amateur astronomer William Huggins , demonstrating that planetary nebulae were gaseous ...
In modern academic writing, the Sun symbol is used for astronomical constants relating to the Sun. [10] T eff☉ represents the solar effective temperature, and the luminosity, mass, and radius of stars are often represented using the corresponding solar constants (L ☉, M ☉, and R ☉, respectively) as units of measurement. [11] [12] [13] [14]
Note on Vertex figure images: The white polygon lines represent the "vertex figure" polygon. The colored faces are included on the vertex figure images help see their relations. Some of the intersecting faces are drawn visually incorrectly because they are not properly intersected visually to show which portions are in front.