Editing Observational cosmology (section)

====Radio====
The brightest sources of low-frequency radio emission (10&nbsp;MHz and 100&nbsp;GHz) are [[radio galaxy|radio galaxies]] which can be observed out to extremely high redshifts. These are subsets of the [[active galaxy|active galaxies]] that have extended features known as lobes and jets which extend away from the [[galactic nucleus]] distances on the order of [[megaparsec]]s. Because radio galaxies are so bright, astronomers have used them to probe extreme distances and early times in the evolution of the universe.