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Here’s a bit of news guaranteed to make you feel old: the moon is rusting.
Earlier this month, researchers published evidence of hematite at the moon’s higher latitudes, and hematite – or Fe2O3 – is an oxide of iron that turns red when it begins to rust. Hematite provides the rosy color on the surface of Mars. But the reddish cast to the Martian surface poses no mystery: astrophysicists are confident that there was once flowing water on Mars (and might still be today … or not).
The moon is different. Why would there be rust on the lunar surface? We know there are trace amounts of water, and we know there’s plenty of iron, but where’s the oxygen coming from? And why is the rust heavily on the side of the moon facing us – that is, the side where the water isn’t?
The sci-fi fans among us, as well as various delightful kooks, would love the answer to be that an alien expedition — Trisolarans, anyone? — has been staging there while studying Earth and is starting to leave traces. The likely explanation is more prosaic, but by no means less impressive: the oxygen is coming from us.
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