On Saturday (Jan. 10), for example, we will see three satellites on one side of Jupiter (going outward from the planet: Ganymede, Io and Europa ), while the fourth ( Callisto) remains all by itself on ...

The Hubble Telescope appears as a tiny silhouette during a perfectly timed solar transit captured from Puerto Rico.

This week, heightened solar activity is stirring Earth’s magnetic field, setting the stage for a northern lights sky show, with auroras visible farther south than usual. Here's everything you need to ...