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UNMercury orbits faster than Neptune because it's closer to the Sun's gravitational pull. The same physics should apply to galaxiesāstars near the center should orbit fast, stars at the edge should orbit slowly. But when Vera Rubin measured dozens of spiral galaxies, she found something impossible: the rotation curves came back flat. Edge stars orbit just as fast as central stars. The only explanation is that galaxies extend far beyond what any telescope can seeāthat visible stars are suspended inside massive halos of invisible matter, halos so enormous that even distant stars feel their gravitational grip.
@universe.unlocked.official
