Edward W. Schwieterman

The smell of fresh bread unmistakably signals a nearby bakery. But to know if baking is happening right now, it's better to catch not the aroma itself but its intensification — the continuous stream of hot air from the oven. This everyday analogy helps grasp a revolution in the search for extraterrestrial life on exoplanets — planets beyond our solar system.

In the orchestra of interstellar life search, every note counts. And the score here is dictated not by man, but by a distant star. For the planet TRAPPIST-1 e, one of seven in the system of an ultracool red dwarf, the conductor's baton is harsh ultraviolet light.

Imagine an artist whose canvas is an entire planet, and whose palette is molecules drinking starlight. His brush is billions of years of evolution, and his painting is a spectral portrait visible even from another star system.

Twelve stars have received X-ray passports. Now, for each of them, we know the exact radiation dose received by a planet in the habitable zone, the region where liquid water is possible.