Galaxies [ ftp://crux.astr.ua.…] are fascinating not only for what is visible, but for what is invisible. Grand spiral [ http://antwrp.gsfc.…] galaxy NGC 1232 [ http://adsabs.harva…], recently captured [ http://www.eso.org/…] in detail by the new Very Large Telescope [ http://antwrp.gsfc.…], is a good example. The visible is dominated by millions of bright stars [ http://antwrp.gsfc.…] and dark dust [ http://antwrp.gsfc.…], caught up in a gravitational swirl of spiral arms rotating about the center. Open clusters [ http://antwrp.gsfc.…] containing bright blue stars can be seen sprinkled along these spiral arms, while dark lanes [ http://antwrp.gsfc.…] of dense interstellar dust [ http://antwrp.gsfc.…] can be seen sprinkled between them. Less visible, but detectable, are billions of dim normal stars and vast tracts of interstellar gas [ http://antwrp.gsfc.…], together wielding such high mass that they dominate the dynamics of the inner galaxy [ http://hermes.astro…]. Invisible are even greater amounts of matter in a form we don't yet know - pervasive dark matter [ http://xrtpub.harva…] needed to explain the motions [ http://www.astro.qu…] of the visible in the outer galaxy. What's out there? [ http://antwrp.gsfc.…]
Explanation
Galaxies [ ftp://crux.astr.ua.…] are fascinating not only for what is visible, but for what is invisible. Grand spiral [ http://antwrp.gsfc.…] galaxy NGC 1232 [ http://adsabs.harva…], recently captured [ http://www.eso.org/…] in detail by the new Very Large Telescope [ http://antwrp.gsfc.…], is a good example. The visible is dominated by millions of bright stars [ http://antwrp.gsfc.…] and dark dust [ http://antwrp.gsfc.…], caught up in a gravitational swirl of spiral arms rotating about the center. Open clusters [ http://antwrp.gsfc.…] containing bright blue stars can be seen sprinkled along these spiral arms, while dark lanes [ http://antwrp.gsfc.…] of dense interstellar dust [ http://antwrp.gsfc.…] can be seen sprinkled between them. Less visible, but detectable, are billions of dim normal stars and vast tracts of interstellar gas [ http://antwrp.gsfc.…], together wielding such high mass that they dominate the dynamics of the inner galaxy [ http://hermes.astro…]. Invisible are even greater amounts of matter in a form we don't yet know - pervasive dark matter [ http://xrtpub.harva…] needed to explain the motions [ http://www.astro.qu…] of the visible in the outer galaxy. What's out there? [ http://antwrp.gsfc.…]
