re temperature of the dark sky in article apr princeton edu richmond spiff princeton edu stupendous man writes henry spencer writes does anyone have a reference something i can look up not just your own recollections i have a few of those myself on the temperature of the night sky as seen from space henry if i read you correctly you may be asking if i put a blackbody in interstellar space disregarding the sun and nearby large warm objects what termperature will it reach in thermal equilibrium with the ambient radiation field if that s the case let me point out that interstellar dust and molecules provide many instances of things that are well not too far from being blackbodies many different observations including iras and cobe have determined that interstellar dust grain temperatures can range from k to k yes but that s because interstellar grains are very poor radiators not remotely black bodies as a consequence they are a lot warmer than the ambient inside the disk of the galaxy the temperature varies quite a bit from place to place how close are you to the nearest ob association i would guess outside the galaxy of course things aren t so varied when i was in graduate school a long time ago we used deg k with a dilution factor of for representative values of the radiant energy background in the galaxy due to starlight ben
