We’ve found a bunch of dwarf galaxies we thought didn’t exist

The missing dwarf galaxies around the Milky Way have been found. Their existence means dark matter could be made of particles that are warmer than we expected

Subscribe today and get the bestselling book How to be Human FREE >

The so-called missing satellites problem has been solved. Based on our models of how dark matter clumps together, we know there ought to be more small satellite galaxies around the Milky Way than we have seen. But we haven’t been able to find them.

Now, there is a simple answer: they were there all along, we just missed them.

Stacy Kim at Ohio State University in Columbus and her team pored through the data from the Sloan Digital Sky Survey (SDSS) and found that extrapolating from the number of galaxies in the survey area – about one third of the sky, thus far – we should be able to detect about 200 satellite dwarf galaxies.

Comparing that number with what current models of dark matter tell us we