Milky Way much bigger than estimated earlier

New observations with Hubble's $70 million Cosmic Origins Spectrograph, or COS, designed by CU-Boulder show that normal spiral galaxies are surrounded by halos of gas that can extend to over 1 million light-years in diameter. A new study has revealed that spiral galaxies like our own Milky Way appear to be much larger and more massive than previously believed.

The current estimated diameter of the Milky Way, for example, is about 100,000 light-years. One light-year is roughly 6 trillion miles. The material for galaxy halos detected by the CU-Boulder team originally was ejected from galaxies by exploding stars known as supernovae, a product of the star formation process, Stocke of CU-Boulder’s astrophysical and planetary sciences department said.

University of Colorado Boulder Professor John Stocke, study leader said, “This gas is stored and then recycled through an extended galaxy halo, falling back onto the galaxies to reinvigorate a new generation of star formation. In many ways this is the ‘missing link’ in galaxy evolution that we need to understand in detail in order to have a complete picture of the process.”