What a wonderful question! The simple answer is that they relied on centuries of previous observations. Remember, even computers have to be programmed with the right data to produce future times of ...

Peering into the past, we find that our ancestors held a surprisingly advanced understanding of the stars and constellations. Their knowledge, as revealed in ancient texts, often rivals our modern ...

More than a thousand years ago, astronomers from the Maya civilization developed one of the most sophisticated time-keeping systems in the ancient world—a system that could predict solar eclipses for ...

Still in its original galaxy, a rare holdout from the second generation of stars sheds new light on the origins of the elements—and how massive supernovae reshaped the cosmos ...

In January, while examining ancient texts at Italy’s National Central Library of Florence, historian Ivan Malara found an unexpected set of handwritten notes. He was reviewing a 1551 printed edition ...

Before telescopes, ancient Greek astronomers relied on naked-eye observations of the night sky to understand the universe around them. The meticulous star catalog belonging to one of the best of these ...

A rare star reveals how the Universe's first stars exploded, helping explain the Milky Way’s outer halo and its unusual chemistry.