fireball

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The house shook yesterday at 4:36pm. It was a single shock, rattling the windows but doing no damage. Jen and I speculated about it over a glass of wine. Earthquake? There was no record of an earthquake on the US Geological Survey earthquake tracking site. Sonic boom? That was my best guess, although it would have to be a military aircraft, and they have strict standing orders not to fly supersonic around populated areas. I remember how a supersonic fighter broke a couple of hundred windows in Tucson when I was a kid in the mid-60’s, but I digress…

Speculation was rampant on our nextdoor.com neighborhood site, as people all over Fairfax reported experiencing the same thing. Finally, one of the residents in the area nailed it — we had a big meteor, a fireball, cruise right over the middle of the bay area at 4:33pm! The picture is from the American Meteor Society tracking section, showing a dozen reports from observers that enabled them to estimate the path of the fireball. Sure wish I’d seen it!

These things start to burn up at around 50 or 70 miles up in the atmosphere, and can make it all the way to the ground on occasion (a meteorite). According to the witnesses, this fireball burned up in the air, so it was probably a baseball-sized rock. It was traveling way faster than the speed of sound, perhaps five or ten miles per second, so it created a hell of a sonic boom.

My brain cheerfully digests data like this. One witness in Tomales (not too far away) reported hearing the sonic boom 3-4 minutes after seeing the meteor. That totally makes sense — we heard it at 4:36, sound travels about 1 mile every 5 seconds, so 3-4 minutes would be 36 to 48 miles away. The flight path over southern Marin was about 9 miles away from us, so the fireball was roughly 35 to 45 miles up in the atmosphere. The math checks.

More interesting is how I feel after a nearby cosmic event. This little chunk of rock traveled around our solar system (or further, who knows?) for probably millions or billions of years, to end it’s life in a 10-second encounter with our precious atmosphere. If it had been bigger, there would be a hole somewhere near Concord now, and if it had been the size of a bus, the hole would be pretty damn big. I am reminded how precious our lives are, how ephemeral, and how easily I take myself and world events so seriously. I vow to savor my day today.

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