Impacts of extraterrestrial bodies are often thought of as life's antagonists in Earth's saga. Ever since the extinction of the dinosaurs was linked to an asteroid impact, scientists have scoured the rock record for evidence of an extraterrestrial cause for other extinction events, and scoured the skies for asteroids on a collision course with our planet. But the effects of impacts are not all deleterious to life: on page 1045, Zita Martins, Mark Price and co-authors demonstrate that impacts could have created life's building blocks. And Kieren Howard and colleagues demonstrate on page 1018 that biological compounds can survive in the melted and ejected products of impact.

Compared with most terrestrial geologic processes, impacts are extreme. When a meteorite or comet hits a planet at speeds of many kilometres per second, it generates a shockwave. As the shockwave propagates away from the point of impact, both target and impactor experience high pressures and temperatures, leading to displacement and ejection of material and formation of a crater within a geological instant. Rocks that are neither vaporized nor melted may be subject to other shock-induced deformation, as is evident within the crystal lattices of minerals where planar features are diagnostic of impact. No other geologic process is quite as, literally, shocking.

But geologic violence can bring creation. As demonstrated on page 1045, when an icy comet hits a rocky planet, the impact could lead to the shock-synthesis of complex amino acids. Similarly, the impact of a meteorite into an ocean could also synthesize complex organic compounds (http://doi.org/fpphvd). On an early Earth with frequent large impacts, shock-synthesis could have generated the key ingredients that life needed to get going.

The seeds of life may also survive the extreme conditions of impact. Once-molten droplets flung from a small crater in Tasmania and quenched to glass were found to contain perfectly preserved organic material from the target ecosystem (page 1018). The find suggests we might examine impact glasses elsewhere for snapshots of life through Earth history and perhaps even life exchanged between planetary bodies.

The same extreme processes that could have helped to create and spread life on Earth continue to threaten it. The Chelyabinsk airburst highlighted the risk presented by even small objects (http://go.nature.com/NblFEP). As we monitor the skies and ponder life's beginnings, impacts continue to bring the drama.