Astronomers have discovered potentially the most massive black hole ever detected. The cosmic behemoth is close to the ...

Jupiter's four Galilean moons will line up in front of Jupiter in the early morning sky on Aug. 8. The predawn hours of Aug ... with Venus visible as a bright morning "star" less than 5 degrees to its ...

That cosmologists cannot agree on one of the most elementary facts about the universe is striking enough. But that ...