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Jun 21

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What is Dark Matter? – Science Concept of the day!

Dark matter is a mysterious form of matter which exerts gravitational effects on ordinary matter but cannot be observed via any other means. While conventional matter can be detected through stellar activity, light scattering, radio emissions, and other means, dark matter clouds are invisible to the vast majority of our instruments. Yet they constitute 90% – 99% of the matter in the universe.
In the 30s, astronomers Fritz Zwicky and Sinclair Smith performed an analysis of the velocity of galaxies within the large galactic clusters Virgo and Coma. They discovered that all galaxies were moving between ten and a hundred times faster than they should be, given the estimates based on observed stellar density. Something unseen was generating additional gravity.

Although Zwicky and Smith’s initial observations seemed to provide strong evidence for dark matter, not all cosmologists were convinced. Because these galactic clusters were so far away, it was hard to accurately measure the independent velocities of each galaxy on a timescale of mere decades. Stronger evidence came in the 70s when scientists such as Rubin, Freeman, and Peebles began to analyze the rotation curves of galaxies. Stars in spiral galaxies, such as our very own, were moving faster around the galactic core than their observable mass would indicate.

It was eventually discovered that all galaxies contain dark matter halos that stretch far beyond the bounds of the galaxy indicated through a telescope.

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Permanent link to this article: http://www.explainstuff.com/2009/06/21/what-is-dark-matter-science-concept-of-the-day/

4 comments

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  1. Mike.Schonvisky

    I’m sharing this post on – Short Science Articles my facebook wall.

  2. Kim

    Dark Matter – what’s the distribution ? – are we talking about the ether ?

  3. admin

    This post is talking about Cosmology. Read here for more in detail at wikipedia.org

    http://en.wikipedia.org/wiki/Dark_matter

  4. santosh

    In the Core of the Earth and other heavy bodies, matter gets attracted from all sides. Gravitational forces will be from all sides at the center of the earth causes breakup of nucleus of atoms at the core. When this force exceeds the strength of the force holding the atom/ nucleus of the atom, the atom will break releasing lot of heat energy and will form a different form of material with much heavier density.
    this is called black matter / black hole
    material what we see in day today life is porous, electron, proton and neutron occupies a fraction of space for an atom.
    but in the core of earth it changes and these spaces disappears to form heavy material.

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