Every day, millions of tiny rocks from space, no bigger than specks of dust, reach our planet. Known as micrometeorites, they are billions of years old, and were once part of the oldest rocks in our solar system. According to experts, about 12 micrometeorites now land on every square metre of our planet every year. This might not sound much, but in total it comes to 100 tonnes a day. 12 tonnes of that mass consists of water molecules. Furthermore, the micrometeorites also contain complex organic molecules of the sort required, for instance, for DNA. So this abundant rain of particles contains, as well as water, the stuff of life itself. However, every day, other tiny particles also land, but they're not from outer space: things like dust from construction, exhaust fumes and sand. These terrestrial particles outnumber the micrometeorites by a billion to one. So when Jon Larsen, a Norwegian jazz musician, became fascinated by micrometeorites and began looking for them, he thought he would probably be unsuccessful. The experts he contacted were certain he would be. Until then, the only micrometeorites ever identified had been found in the Antarctic. Since falling to Earth billions of years ago, these had mostly been locked into rock and ice. Scientists knew how important it is to study micrometeorites, and were tantalised by the prospect that they might contain hints as to how life started on Earth. Yet no one had ever found recently arrived examples. In fact, so extremely unlikely was it that they hadn't even tried.