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  • BBC Sky at Night

    CUTTING EDGE

    Mar 24, 2022 4 minutes

    Hunting for life, but not as we know it

    Ammonia could be as important on other worlds as oxygen is on ours

    Over the coming years, as astronomers use spectroscopy to read the atmospheres of Earthsized, habitable planets, detecting the presence of one gas will be an important discovery: oxygen. On Earth, oxygen is released by life - specifically, by organisms using sunlight for energy.

    Oxygen is a very reactive gas. Early in Earth’s history any oxygen released into the atmosphere was rapidly removed. It reacted with rocks, or was destroyed by photochemical reactions driven by ultraviolet rays in sunlight. Such processes are known as ‘sinks’, and oxygen only started to accumulate

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