The formation of our solar system from a singular nebula raises an intriguing question: why did each planet develop with a ...

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Saturn’s rings, imaged here by NASA’s Cassini orbiter, are one of the solar system’s most reliably spectacular sights. But ...

Starting up again Saturday, a sweeping view of our solar system will glow in the night sky. The planetary alignment, or a ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...