In the search for a cosmological model that perfectly explains our universe, most astronomers invoke the notion of dark matter. But what if they should instead modify the age-old laws of gravity? Keith Cooper explores the struggles and successes of modified gravity in explaining phenomena at varying galactic scales, as well as matching observations from the cosmic microwave background. Also this month, explore NASA's plans for fission-powered nuclear rockets, explore the ethics of commercial space flight and find out why disco balls could be good news for astronomy.
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