Did You Watch the Perseids?

This past week the Perseids meteor shower came to its peak. Of course, social media came alive with hints of a huge shower. People followed up by posting pictures of meteors from their observing sites. It’s an annual event, and most people had clear skies for it. We got a chance to see a few Perseids starting a week or so before the peak, but the actual night, it was cloudy at our place. Some years we get the bear, some years the bear gets us.

The bigger story about the Perseids isn’t what you got to see, although it’s pretty neat to watch these bits of space debris flash into oblivion as they enter Earth’s atmosphere. It’s really about what these things represent. And that is a whole lot of ancient solar system history.

The Ancient Source of the Perseids

The Perseids shower is made up of countless particles of dust that stream off of Comet Swift-Tuttle as it passes around the Sun every 133 years. Earth’s orbit intersects that stream beginning in late July through part of August each year. The peak coincides when we’re passing through the thickest part of the stream. That means we see more meteors that night.

Comet Swift-Tuttle originated early in the solar system’s history and is made of ices and dust that existed back when the Sun and planets were beginning to form. That means its materials pre-date the birth of the Sun. As the system formed and evolved, the planets did their dynamical dance to their current orbits, and in the process, sent chunks of ice out to the outer solar system. From there, those chunks got gravitational nudges that eventually sent them on long orbits around the Sun. Swift-Tuttle is one of those chunks.

So, when you see a Perseid meteor — or any meteor for that matter — flash across the sky, you’re watching a piece of solar system history vaporize before your eyes. Occasionally a chunk is large enough to reach the ground and become a meteorite. Anyone who finds it is holding a piece of cosmic history in their hands. Think about THAT the next time you see a meteor flare in fiery death overhead.