In a galaxy far away, gravity didn’t quite work the way it does on Earth. And the speed at which everything moved was really ...

Whether or not galaxies merge depends on how strong the gravitational attraction is between the galaxies and whether the universe's expansion is more powerful than gravity. Gravity affects everything ...

Our Solar System orbits the galactic center at an estimated 792,000 kilometers per hour, taking 225 million Earth years to complete one galactic year. Meanwhile, the Milky Way as a whole is thought to ...