Search results
Results from the WOW.Com Content Network
A celestial map by the Dutch cartographer Frederik de Wit, 1670. A star chart is a celestial map of the night sky with astronomical objects laid out on a grid system. They are used to identify and locate constellations, stars, nebulae, galaxies, and planets. [1]
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. [1] [2] The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System.
NGC 4567 and NGC 4568 (nicknamed the Butterfly Galaxies [4] or Siamese Twins [NB 1] [5]) are a set of unbarred spiral galaxies about 60 million light-years away [1] in the constellation Virgo. They were both discovered by William Herschel in 1784. They are part of the Virgo Cluster of galaxies.
A simple chart for classifying the main star types using Harvard 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 ...
Evidence of these constellations has survived in the form of star charts, whose oldest representation appears on the statue known as the Farnese Atlas, based perhaps on the star catalogue of the Greek astronomer Hipparchus. [43] Southern constellations are more modern inventions, sometimes as substitutes for ancient constellations (e.g. Argo ...
The asterism was recognized as the constellation ASH.IKU "The Field" on the MUL.APIN cuneiform tablets from about 1100 to 700 BC. [13] Alpheratz is now only considered a part of the constellation Andromeda whereas formerly the star was a part of both constellations. The Bowl of Virgo is formed by the stars Beta, Gamma, Delta, Epsilon and Eta ...
The Sigma-D relation (or Σ-D relation), used in elliptical galaxies, relates the angular diameter (D) of the galaxy to its velocity dispersion. It is important to describe exactly what D represents, in order to understand this method. It is, more precisely, the galaxy's angular diameter out to the surface brightness level of 20.75 B-mag arcsec ...
The Gould designation for stars visible from the southern hemisphere, introduced by Benjamin Gould (1879), also lists stars by constellation, numbered by increasing right ascension. Hevelius and Bode both numbered stars within constellations similarly. Their number systems have fallen out of use, but their designations even now are occasionally ...