The megaparsec (abbreviated Mpc) is a unit of distance used in astronomy, equal to one million parsecs. The parsec (symbol pc) is a unit of length used in astronomy. ...
It is the most common unit of distance employed in extragalactic astronomy. Extragalactic astronomy is the branch of astronomy concerned with objects outside our own Milky Way Galaxy (the study of all astronomical objects which are not covered by galactic astronomy). ...
This article is about the unit of length. ... The parsec (symbol pc) is a unit of length used in astronomy. ... A light year (or light-year, or lightyear), abbreviated ly, is the distance light travels in one year: about 9. ... The metre (Commonwealth English) or meter (American English) (symbol: m) is the SI base unit of length. ... A zettametre (American spelling: zettameter) (symbol: Zm) is a unit of length equal to 1021 metres. ... A gigaparsec (one billion parsecs, 1Gpc) is the largest used measure in existence. ...
Presentation of the solar system (not to scale) The solar system comprises the Earths Sun and the retinue of celestial objects gravitationally bound to it. ... Note: This article contains special characters. ... Note: This article contains special characters. ... This image is a Galaxy Evolution Explorer observation of the large galaxy in Andromeda, Messier 31. ... A sky field near some of the brighter galaxies in the Virgo cluster. ... RXJ1242-11 (also known as Galaxy RXJ1242-11) is a galaxy located approximately 200 megaparsecs from Earth. ...
Hubble Constant The present expansion rate of the universe, symbolized by H and measured in units of km/s/Mpc or kilometers per second per megaparsec.
The exact value of the Hubble constant is still somewhat uncertain, but is generally believed to be around 65 kilometers per second for every megaparsec in distance.
The standard CDM model that emerged in the mid-1980s served a very useful purpose because it established that the underlying cosmology was a flat Friedmann model with a Hubble constant of 50 kilometres per second per megaparsec,...
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