Rings of comets have been discovered around 74 alien star systems, revealing not only the existence of trillions of icy exocomets, but also the source of most of the water in these systems. The ...

A visitor is hurtling through the void, a silent, ancient vagabond from an alien star system, and by the end of the week, it will make its closest ever approach to Earth. This is no ordinary comet; it ...