Of course, outliers that don’t follow the model’s predictions should exist. And three systems is still an extremely small number — but even so few observations now show that satellites are much more likely to orbit in an orderly fashion than believed. It’s looking like the standard cosmological model, which states that galaxies are largely made up of dark matter, may need some tweaks. “Coherent movement seems to be a universal phenomenon that demands new explanations,” said Oliver Müller of the University of Basel in Switzerland, and lead author of the study, in a press release Centaurus A is an ideal object around which to study satellite galaxies because its satellites appear arranged neatly on a plane that is perpendicular to the galaxy itself, and edge-on when we see it from Earth. That means any Doppler shifting of the light received from the satellite galaxies due to their motion is from their motion around the galaxy’s center, rather than overall motion toward or away from us. Out of 16 satellite galaxies observed, 14 are rotating together around the center of the galaxy. This is consistent with the findings when astronomers observe satellites around the Milky Way and Andromeda.