Gaia

Isaac Newton thought the planetary order was mortal. Three centuries of celestial mechanics answered him, and kept answering: the four giant planets are so securely spaced that chaos alone would need…

The Milky Way ate its neighbors, and the meals left traces. Stars pulled in from galaxies that fell into ours billions of years ago still thread through the outer Galaxy on orbits far more stretched…

There is a stretch of the HR 8799 system that conventional direct imaging has struggled to see. Four giant planets circle the star in the best-known set of pictures in exoplanet astronomy, and every…

A white dwarf is a star that has run out of fuel and collapsed to about the size of Earth, and its gravity is brutal. Anything heavier than helium sinks out of the atmosphere and vanishes from view.…