Physical cosmology Reference Libraries

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2014-01-12 00:00:00

Image Caption: The Hubble Extreme Deep Field (XDF) was completed in September 2012 and shows the farthest galaxies ever photographed by humans. Each speck of light in the photo is an individual galaxy, some of them as old as 13.2 billion years; the observable universe is estimated to contain more than 200 billion galaxies. Credit: NASA/Wikipedia What is Cosmology? I once commented to an...

Virgo Cluster
2010-09-16 15:18:29

The Virgo Cluster consists of galaxies at a distance of around 59 Mly away in the constellation Virgo. Containing between 1300 to 2000 galaxies the Virgo Cluster is the heart of the Local Supercluster. Its mass is estimated at 1.2 × 1015 M☉ out to 8 degrees of the cluster's center or a radius of about 2.2 Mpc. Most of the brighter galaxies in the cluster were discovered by Charles...

Coma Cluster
2010-09-13 16:56:08

The Coma Cluster (Abell 1656), along with the Leo Cluster, is one of two major clusters compromising the Coma Supercluster. It contains over 1000 identified galaxies. Most of the galaxies in the center of the Coma Cluster are elliptical galaxies including both dwarf and giant. However the center is dominated by NGC 4874 and NGC 4889, two giant elliptical galaxies. The brightest galaxies are...

JKCS 041
2010-09-08 16:02:39

As of 2009, JKCS 041 is a group of galaxies with the distinction of being the farthest away group from Earth ever observed. Seen at redshift 1.9, it is estimated to be 10.2 billion light years away. The cluster is located within the constellation Cetus at a photometrically determined redshift of z=1.9 at right ascension 2h 26m 44s declination -04° 41"² 37"³ (J2000.0).

2014-01-12 00:00:00

Sample Entry: Astronomy is the scientific study of stars, planets, comets, galaxies, and other phenomena that occur outside Earth's atmosphere (e.g. cosmic radiation). Astronomy deals with the evolution, physics, chemical makeup, meteorology, and motion of celestial objects, and also the formation of the universe. The word Astronomy comes from the Greek words astron (meaning "star") and...

Zeldovich Yakov Borisovich
2013-03-16 00:00:00

Yakov Borisovich Zel'dovich (March 8, 1914 "“ December 2, 1987) was a productive Soviet physicist. He was instrumental in the advancement of Soviet nuclear and thermonuclear weapons, and also was an invaluable assistance in the fields of adsorption and catalysis, shock waves, nuclear physics, particle physics, astrophysics, physical cosmology, and general relativity. In 1914, he was born...

String Theory
2004-10-19 04:45:44

String Theory -- A string theory is a physical model whose fundamental building blocks are extended objects (strings, membranes and higher-dimensional objects) rather than points. String theories are able to avoid problems, such as infinite energy density, associated with the presence of mathematical points in a physical theory. The term 'string theory' properly refers to both the 26...

Large-Scale Structure of the Cosmos
2004-10-19 04:45:44

Large-Scale Structure of the Cosmos -- Stars are organised into galaxies which in turn appear to form clusters and superclusters, separated by voids. Prior to 1989 it was commonly assumed that the superclusters were the largest structures in existence, and that they were distributed more-or-less uniformly throughout the universe in every direction. However, in 1989, Margaret Geller and...

2004-10-19 04:45:44

Cosmology -- area of science that aims at a comprehensive theory of the structure and evolution of the entire physical universe. Modern Cosmological Theories Present models of the universe hold two fundamental premises: the cosmological principle and the dominant role of gravitation. Derived by Hubble, the cosmological principle holds that if a large enough sample of galaxies is...

2004-10-19 04:45:42

Redshift -- Redshift is the phenomenon that the frequency of light when observed, under certain circumstances, can be lower than the frequency of light when it was emitted at the source. This usually occurs when the source moves away from the observer, as in the Doppler effect. More specifically, the term redshift is used for the observation that the spectrum of light emitted by distant...

Word of the Day
  • an ornament or knob in the shape of a flower
  • In architecture, a floral ornament; specifically, the large conventional flower usually placed in the center of the abacus of a Corinthian capital or classic ceiling-caisson; also, the floreated termination of a Gothic finial.
[ "The word 'fleuron' comes from French."]