Astronomers may have underestimated the extent to which interstellar dust obstructs our view of other galaxies. New research suggests that dust blocks half of all the starlight in the universe from reaching Earth, meaning there is a lot more light and radiation out there than previously accounted for. By looking at galaxies in different orientations, Simon Driver, director of St. Andrews Observatory in Scotland, observed how much light the dust within spiral galaxies blocked. Using a new model of dusty galaxies developed by Richard Tuffs of the Max Planck Institute for Nuclear Physics, Driver then recalculated how much energy the dust blocks for 10,000 galaxies. The newly calibrated model showed far more hidden energy than expected; that energy then heats up the obscuring dust.
If this finding holds up, we may have to reevaluate the numbers of known stars in a galaxy, how much mass the stars contain, and how much radiation escapes a galaxy.