Protoplanetary disk Reference Libraries

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2004-10-19 04:45:44

Cosmogony -- Cosmogony is the study of the origins of celestial objects. It is most commonly used to refer to the study of the origin of the solar system. Currently, the most widely accepted theory is that the solar system was formed roughly 5 billion years ago with the collapse of a nebula of gas and dust, likely caused by shock waves generated by a nearby supernova. The solar system...

Accretion Disk
2004-10-19 04:45:41

Accretion Disk -- An accretion disk is a structure formed by material falling into a gravitational source. Conservation of angular momentum requires that, as a large cloud of material collapses inward, any small rotation it may have will increase. Centrifugal force causes the rotating cloud to collapse into a disk, and tidal effects will tend to align this disk's rotation with the rotation...

2004-10-19 04:45:40

Vega -- Vega (Alpha Lyrae) is the lead star in the constellation Lyra, reaching near directly overhead the mid-northern latitudes, during the summer. It's a "nearby star" at only 25 light years distant and together with Arcturus and Sirius, one of the brightest stars in the Sun's neighbourhood. Vega is a vertex of the Summer Triangle. Its spectral class is A0V (Sirius, an A1V, is slightly...

Word of the Day
  • A gigantic fictional humanoid alien god being described with a head resembling an octopus and dragon wings and claws, around whom an insane cult developed.
  • Pertaining to the mythos of Cthulhu and additional otherworldly beings created by H. P. Lovecraft or inspired by his writings and imitators.
This word was invented in 1926 by H.P. Lovecraft for his short story, 'The Call of Cthulhu.' 'Cthulhu' may be based on the word 'chthonic,' which in Greek mythology refers to the underworld.