28-Fire: Does a planet need life for fire to burn?

Think about what types of things burn: wood, grasses, fossil fuels… mostly things that were formed by life. Fire also requires oxygen, which is largely produced by life. Did Earth have fire before life evolved? Could any other planets have fire? If there were an exoplanet with fires burning, would we have any way to detect that?

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17-Ice: Stolen moon ice

When you think of ice, you might imagine glaciers, the North Pole, a clink in your water glass. But it turns out that our closest neighbor in space isn’t just a dusty ball—the moon has ice tucked away in deep craters at each of its poles. On top of that, scientists think the moon stole its ice: from comets, asteroids, maybe even from the Earth.

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