About 7.4 light-years from the Sun, a dim ball of gas about as wide as Jupiter drifts through space with no star to warm it. Jupiter is large enough to fit some 11 Earths side by side. (A light-year is the distance light travels in a year, nearly 6 trillion miles.) That puts the object […]

For more than three centuries, astronomers asking whether the Solar System is stable have received ever more comforting answers. Isaac Newton was not so sure. He suspected that the mutual tugs between Jupiter and Saturn would eventually wreck the planetary order, and that only divine intervention could prevent it. By the late 1700s, Laplace and […]