Footnote
c Dark matter was postulated in the 1930’s and confirmed in the 1980’s. Today astronomers measure how much dark matter a cluster of galaxies may have by observing how the cluster bends light from more distant objects.
c Dark matter was postulated in the 1930’s and confirmed in the 1980’s. Today astronomers measure how much dark matter a cluster of galaxies may have by observing how the cluster bends light from more distant objects.