But gas clouds are hard to detect - they are composed mostly of nearly invisible molecular hydrogen and helium . Therefore, over the past decade, a team of astronomers have carefully mapped out the molecular sky to unprecedented clarity - to about four times previous resolution and about eight times previous sensitivity. The resulting map is shown above , rescaled and in false color, with dark blue being relatively low emission. The band of our Milky Way Galaxy spans the middle. The data have not only helped our understanding of the Galaxy , but highlight a few mysteries too.
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