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 ...

Seconds after the Big Bang, the Universe exhibited an astonishing simplicity. Observations reveal a spatially flat, radiation-dominated cosmos described by a Friedmann–Robertson–Walker (FRW) metric.

Nothing in our universe stands still: Earth orbits the sun, the sun circles the galaxy, and even galaxies are constantly on the move. So why is everything in space in motion? It all comes down to how ...

The universe's expansion is similar to a balloon inflating; the surface expands, causing dots (galaxies) to move apart. Galaxies farther away from us appear to recede faster than closer ones. The ...