Gravity used to be the most dependable rule in the cosmic rulebook, the quiet background force that never changed its mind. Now a series of discoveries and bold claims are turning that certainty into ...

Editor’s note: This story was originally published on April 6, 2023, and was updated on Jan. 29, 2026, to reflect the latest developments in the Artemis program. With the success of NASA’s uncrewed ...

A swarm of galaxies called the Bullet Cluster is the biggest, best natural laboratory for studying dark matter that astronomers have ever seen ...

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