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Synthetic Blue Stars: Synthetic blue stars are often inferior because of the uneven distribution of pigment. Because of its hardness, nine on the Mohs scale, sapphire is also used industrially as thread guides, orifices in oil furnaces, and small spheres in ball-point pens ; because of its unusual dielectric properties, in electrical instruments; because of its transparency and resistance to heat, as windows in high-temperature furnaces; and because of its transparency to ultraviolet and infrared radiation, in optical instruments.
History and Importance. The first quasars, then believed to be stars, were found in 1960 during optical identifications of bright radio sources listed in the Third Cambridge (3C) Catalogue of Radio Sources. Most of the 3C sources that have very small radio angular sizes proved to be quasars. Although it has often been difficult to pick out a quasar from a rich field of stars, recognition of their relatively blue colors has helped in the identifications. More than 50 quasars were known by the mid-1960's.
• The United States Power Squadrons Ensign has 13 blue and white vertical stripes with a fouled anchor and circle of stars in a red union. It is flown to indicate that the Boat is commanded by |
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