The Moon and two planets form a bright triangle tonight. Saturn is above the Moon as night falls, with brighter Jupiter farther to the left of the Moon.

These three bodies are a long way apart — they’re separated by hundreds of millions of miles. And there’s no shuttle service between them. Yet the Moon and some of the moons of the two planets may have traded a lot of stuff over the eons. So may many other planets and moons — including our own.

The exchange is powered by impacts — giant space rocks slamming into planets or moons. Such a collision blasts out huge amounts of debris. Some of it moves fast enough to escape into space. And over time, bits of the debris settle on the other worlds. Here on Earth, for example, we’ve found confirmed pieces of Mars, the Moon, and some asteroids. And scientists suspect they’ve found pieces of other worlds as well.

Spacecraft traveling to Mars and other planets and moons are sterilized to prevent them from carrying microorganisms. And samples from those other worlds are isolated for a while to protect us from deadly bugs. But some scientists argue that the regular exchange means we shouldn’t worry too much about that. They say that pieces are shooting back and forth all the time — and have been for billions of years.

Still, the policies on protecting the worlds of the solar system from each other aren’t likely to change anytime soon.

More about the Moon and Jupiter tomorrow.
 

Script by Damond Benningfield

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