Measurements at other Wavelengths
						� Infrared �Cirrus� � really slightly warm dust � X-Rays of hot gas near exploded stars (supernova) � Radio observations of �Molecular Clouds� � Called that because cool and dense enough for molecules to form � H2 also hard to detect � CO common and easy to detect � Densest have 1000 atoms/cm3 � T as low as 10 K � Location of star formation