Astronomers expected a young supernova remnant like the Crab Nebula to be packed with smoke-particle-size dust. But NASA's heat-sensing Spitzer Space Telescope shows the Crab is "smoke free." This composite merges an optical image of the nebula with Spitzer views at 3.6, 5.8, 8.0, and 24 microns.
NOAO/AURA/NSF/NASA/JPL/SSC/T. Temim et al.