Noted: Elena D’Onghia at the University of Wisconsin, Madison, had predicted in 2009 that unless gravity is doing something very strange, we should see clusters of dwarf galaxies all on their own, even near our galaxy. “Based on dark matter theory, we expect a lot of little dwarf galaxies and clumps of dark matter in and around the Milky Way,” she says. So why have these clusters been so hard to spot?
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