... Tonight's Sky . ... Observing . ... Comet Wild 2: First evidence of space weathering . ... This space weathering has deposited nanometer-sized grains of iron metal and reddened the surface of the comet. т??This is the first mineralogical evidence for space weathering that has been identified in the Wild 2 samples that was hinted at by other spectroscopic observations of the comet,т?? said Bridges. т??It adds another piece of the puzzle to our understanding of the life history of comets.т?? ...