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Astronomers claim in a new paper that star motions should make it easy for civilizations to spread across the galaxy, but still we might find ourselves alone.
Computer simulations have become so accurate that cosmologists can now use them to study dark matter, supermassive black holes and other mysteries of the real evolving cosmos.
Textbooks say that the moon was formed after a Mars-size mass smashed the young Earth. But new evidence has cast doubt on that story, leaving researchers to dream up new ways to get a giant rock into orbit.