We still don't fully understand what triggers lightning. A new study suggests that showers of cosmic rays may be the missing link. Cosmic rays may offer an out-of-this-world answer to a long-standing ...

Astronomers have discovered a remarkably clumpy rotating galaxy that existed just 900 million years after the Big Bang, shedding new light on how galaxies grew and evolved in the early universe.

You could swim through the deepest voids and encounter a single hydrogen atom in an entire football field's worth of space. At the very largest scales, galaxies are not scattered around randomly.