The Galactic Plane in infrared
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The emission of the cold dust and gas is invisible to us when observed in normal light, however, this material instead emits at longer wavelength infrared light. Thus, observations of the sky in infrared light can tell us where and how this invisible gas and dust are distributed across the Galaxy. In the regions where stars are actively being formed, the dust is warmed up by the stellar light and also emits in infrared light. Therefore, by tracing this infrared emission we can search for and study the site of current active star formation in our Galaxy.
The stars that we see in the visible images of our Galaxy represent only a fraction of the total material of our Milky Way. In addition there are copious amounts of cold gas and dust existing at temperatures below -200 C. The distribution of this cold gas and dust is not uniform. High density regions gravitationally attract more and more matter from the surrounding regions, until eventually stars are formed.
More stunning images of the Orion Region, Cignus-X Region, and the Large Magellanic Cloud from Akari Results July 2007
Planetary Debris and its effects from Centauri Dreams
Star Surface Polluted by Planetary Debris ESO Science Release
Astronomers Get Better View Of Density Waves In Galaxies @ Science Daily