The study was the first 'spectral variability' survey to study how galaxies change brightness at different frequencies. Feb 08, 2021 13:29:51 IST Radio images of the sky have revealed hundreds of “baby” and supermassive black holes in distant galaxies, with the galaxies’ light bouncing around in unexpected ways. Galaxies are vast cosmic bodies, tens of thousands of light years in size, made up of gas, dust, and stars (like our Sun). Given their size, you’d expect the amount of light emitted from galaxies would change slowly and steadily, over timescales far beyond a person’s lifetime. But our research, published in the Monthly Notices of the Royal Astronomical Society, found a surprising population of galaxies whose light changes much more quickly, in just a matter of years.