26-02-11

Dark Matter: New Evidence on How Galaxies Are Born

 

By Michael D. Lemonick Wednesday, Feb. 23, 2011

 

dark matter,halo,cosmology

Copyright : http://commons.wikimedia.org/wiki/File:Hs-2007-17-a-full_...

 

If you think it's hard to swallow the concept of dark matter, you're not alone.

 

Decades ago, a few astronomers began to suspect that the universe was swarming with some mysterious, invisible substance that was yanking galaxies around with its own powerful gravity.

 

And for those same decades, most of those astronomers' colleagues dismissed the notion as pretty much nuts.

 

But the evidence kept mounting, and nowadays dark matter is a firmly established concept in modern astrophysics.

 

It pretty much has to exist, in fact, to explain why individual galaxies spin as fast as they do without flying apart, and why groups of galaxies move the way they do in relation to one another.

 

If there weren't 10 times as much dark matter as there are stars and gas clouds and other visible matter, the universe would make no sense.

 

Nature abhors irrationality, and so we live in a universe in which just about every galaxy, including the Milky Way, is held safely inside a huge blob of dark matter like a butterfly floating inside a glass paperweight.

 


Copyright and Read more

 

http://www.time.com/time/health/article/0,8599,2052614,00...

 

 

 

18-02-11

Dark energy is not directly detectable, but scientists can track its footsteps through history.

 

dark matter,the hunt,cosmology

 

copyright

http://upload.wikimedia.org/wikipedia/commons/c/c9/Dark_m...

 

A massive survey of distant galaxies should help unravel a mind-bending cosmic mystery: Why has the expansion of the universe sped up ?


copyright

http://news.discovery.com/space/dark-energy-galaxies-univ...

 

 

17-02-11

Herschel finds less dark matter but more stars

 

dark matter,Herschel

copyright

http://upload.wikimedia.org/wikipedia/commons/9/9d/Struct...


16 February 2011

 

ESA’s Herschel space observatory has discovered a population of dust-enshrouded galaxies that do not need as much dark matter as previously thought to collect gas and burst into star formation.

 

copyright

http://www.esa.int/esaCP/SEMRQ3PT1KG_index_0.html