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