We measure the extremely long distances between things in space by light years. A light year is the distance that light travels in one Earth year. Light travels at about 300,000 kilometres per second.

This stunning 527-megapixel composite reveals both visible and infrared views of young stars, ionized gas, and dust filaments ...

Quasar 0957+561, the first known gravitationally lensed quasar, lies near NGC 3079 in Ursa Major. Here's how to find and ...