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The right combination of gases could put exoplanets through an explosive sea change. Hydrogen and oxygen in an atmosphere can ignite and leave behind water, a reaction that could dump oceans onto a planet’s surface.
John Lee Grenfell at the German Aerospace Centre in Berlin and his colleagues calculated how oxygen could build up in a planet’s atmosphere and combine with hydrogen to create water. They found that at high enough temperatures, the combination could combust or explode, lighting up the planet’s sky with …