This illustration shows how the Hubble Space Telescope
searches for missing ordinary matter, called baryons, by
looking at the light from quasars several billion light-years
away. Imprinted on that light are the spectral fingerprints
of the missing ordinary matter that absorbs the light at
specific frequencies shown in the colorful spectra at right.
The missing baryonic matter helps trace out the structure
of intergalactic space, called the "cosmic web." (Credit:
Image courtesy Space Telescope Science Institute, NASA)
Now, in an extensive search of the relatively recent, local universe, University of Colorado at Boulder astronomers said they have definitively found about half of the missing normal matter, called baryons, in the spaces between the galaxies. This important component of the universe is known as the intergalactic medium and it extends essentially throughout all of space, from just outside our Milky Way galaxy to the most distant regions of space observed by astronomers.
