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Stellar classification. In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines.
The Sun is the brightest star as viewed from Earth, at −26.78 mag. The second brightest is Sirius at −1.46 mag. For comparison, the brightest non-stellar objects in the Solar System have maximum brightnesses of: the Moon −12.7 mag [1] Venus −4.92 mag. Jupiter −2.94 mag. Mars −2.94 mag.
P. ochraceus. Binomial name. Pisaster ochraceus. (Brandt, 1835) [1] Pisaster ochraceus, generally known as the purple sea star, ochre sea star, or ochre starfish, is a common seastar found among the waters of the Pacific Ocean. Identified as a keystone species, P. ochraceus is considered an important indicator for the health of the intertidal zone.
Such is the case for the sweeping purple and green lights that can hover over the horizon in the Northern Hemisphere. The phenomenon looks like an aurora but is in fact something entirely different.
The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, [1] that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin -based chlorophyll, making the surface biosphere appear purplish ...
Hypergiant. A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term hypergiant is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications ...
Shades of purple. There are numerous variations of the color purple, a sampling of which is shown below. In common English usage, purple is a range of hues of color occurring between red and blue. [1] However, the meaning of the term purple is not well defined. There is confusion about the meaning of the terms purple and violet even among ...
The Medal of Honor (solid green bar speckled tiny gold stars) is awarded for: Individual acts of extraordinary bravery intelligently performed in the line of duty at imminent and personal danger to life. Specifically, the Department Medal of Honor is awarded for acts of gallantry and valor performed with knowledge of the risk involved, above ...