Cassiopeia A

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3C461, Cassiopeia A, in X-rays

Cassiopeia A (Cas A) is a supernova remnant in the constellation Cassiopeia and the brightest extra solar radio source in the sky, with a flux of 2720 Janskys at 1GHz. It is believed to be approximately 300 years old but there are no historical records of any sightings of the progenitor supernova, probably due to interstellar dust absorbing optical wavelength radiation before it reached Earth. Possible explanations lean toward the idea that the source star was unusually massive and had previously ejected much of its outer layers. These outer layers would have cloaked the star and reabsorbed much of the light released as the inner star collapsed. In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Remnant of Keplers Supernova, SN 1604. ... The Crab Nebula is an expanding cloud of gas created by the 1054 supernova. ... The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos) is the galaxy in which the Earth is found. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Cassiopeia is a northern constellation which greek mythology considered to represent a vain queen. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... Many galaxies, including the Milky Way in which our Sun and Earth are located, are disk-shaped: the majority of their visible mass (excluding possible dark matter) lies very close to a plane. ... 1947 was a common year starting on Wednesday (link will take you to calendar). ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... The Crab Nebula is an expanding cloud of gas created by the 1054 supernova. ... Cassiopeia is a northern constellation which greek mythology considered to represent a vain queen. ... In radio astronomy, the flux unit or jansky (abbreviation Jy) is a non-SI unit of electromagnetic flux equivalent to watts per square metre per hertz. ... Remnant of Keplers Supernova, SN 1604. ... Interstellar cloud is the generic name given to accumulations of gas and dust in our galaxy. ...

Cas A is 3C461 in the third Cambridge catalog of radio sources and G111.7-2.1 in the Green Catalog of Supernova Remnants. The Third Cambridge Catalog of Radio Sources (3C) is an astronomical catalogue of celestial radio sources, was published in 1959 by the University of Cambridge. ...

It is known that the expansion shell has a temperature of around 50 million degrees, and is travelling at more than ten million miles per hour.

Cas A is the strongest radio source in the sky beyond our solar system, and was among the first discrete sources to be found, in 1947. The optical component was first identified in 1950. In 1999, the Chandra X-Ray Observatory found a "hot point-like source" [1] close to the center of the nebula that is quite likely the neutron star or black hole predicted but not previously found. Mosaic of the Solar System planets except Pluto, including Earths Moon (not to scale). ... 1947 was a common year starting on Wednesday (link will take you to calendar). ... 1950 was a common year starting on Sunday (link will take you to calendar). ... 1999 is a common year starting on Friday of the Common Era, and was designated the International Year of Older Persons by the United Nations. ... Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. ... Cross section of a neutron star A neutron star is a type of degenerate star composed mostly of densely packed neutrons, generally about 20 km in diameter and as massive as an average star. ... An artists impression of a black hole with a closely orbiting companion star that exceeds its Roche limit. ...

Calculations working back from the currently observed expansion point to an explosion around 1667, although astronomer William Ashworth and others have suggested that the Astronomer Royal John Flamsteed may have inadvertently observed the supernova in 1680. At any rate, no supernova in the Milky Way has been visible to the naked eye from Earth since. // Events January 20 - Poland cedes Kyiv, Smolensk, and eastern Ukraine to Russia in the Treaty of Andrusovo that put a final end to the Deluge, and Poland lost its status as a Central European power. ... Astronomer Royal is a senior post in the Royal Household of the Sovereign of the United Kingdom. ... John Flamsteed - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Events First Portuguese governor was appointed to Macau The Swedish city Karlskrona was founded as the Royal Swedish Navy relocated there. ... The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Galaxia Kuklos) is the galaxy in which the Earth is found. ...