Falling rock zone

Some of you may have heard of the Sylacauga meteorite -- a 5.5 kilogram, grapefruit-sized piece of rock that gained more notoriety than most because it crashed through a woman's roof on the afternoon of November 30, 1954, and hit her on the hip as she slept on the sofa.

The victim, Ann Hodges of Sylacauga, Alabama, was bruised but otherwise okay.

Here's Hodges with her rock, and an expression that clearly communicates, "A woman can't even take a damn nap around here without this kind of shit happening." 

Hodges isn't the only one who's been way too close to falling space rocks.  In August of 1992 a boy in Mbale, Uganda was hit by a small meteorite -- fortunately, it had been slowed by passing through the tree canopy, and he was startled but unharmed.  Only two months later, a much larger (twelve kilogram) meteorite landed in Peekskill, New York, and clobbered a parked Chevy Malibu:

The most deadly meteorite fall in historical times, though, is a likely airburst and subsequent shower of rocks that occurred near Qingyang, in central China, in the spring of 1490.  I say "likely" because there haven't been any meteorites from the incident that have survived to analyze, but a meteoritic airburst -- a "bolide" -- is the explanation that seems to fit the facts best.

Here's a contemporary account of the event:

Stones fell like rain in the Qingyang district.  The larger ones were four to five catties [a catty is a traditional Chinese unit of mass, equal to about a half a kilogram], and the smaller ones were two to three catties.  Numerous stones rained in Qingyang.  Their sizes were all different.  The larger ones were like goose's eggs and the smaller ones were like water-chestnuts.  More than ten thousand people were struck dead.  All of the people in the city fled to other places.

The magnitude of the event brings up comparisons to the colossal Tunguska airburst of 1908, when a meteorite an estimated fifty meters in diameter exploded above a (fortunately) thinly-populated region of Siberia, creating a shock wave that blew down trees radially outward for miles around, and registered on seismographs in London.

Interestingly, the Qingyang airburst wasn't the only strange astronomical event in 1490; Chinese, Korean, and Japanese astronomers also recorded the appearance of a new comet in December of that year.  From their detailed records of its position, modern astronomers have calculated that its orbit is parabolic -- in other words, it won't be back, and is currently on its way out of the Solar System.  However, it left a debris trail along the path of its one pass near us which is thought to be the origin of the bright Quadrantid meteor shower, which peaks in early January.

It's likely, however, that the Qingyang airburst and the December comet were unrelated events.

Much has been made of the likelihood of Earth being struck by an asteroid, especially something like the Chicxulub Impactor, which 66 million years ago ended the hegemony of the dinosaurs.  Thing is, most of the bigger items in the Solar System's rock collection have been identified, tracked, and pose no imminent threat.  (There is, however, a four percent chance that a seventy-meter-wide asteroid will hit the Moon in 2032, triggering a shower of debris, some of which could land on Earth.)

But there are lots of smaller rocks out there that we'd never see coming.  The 2013 Chelyabinsk airburst was estimated to be from an eighteen-meter-wide meteor, and created a shock wave that blew in windows, and a fireball that was visible a hundred kilometers away.  Our observational ability has improved dramatically, but eighteen meters is still below the threshold of what we could detect before it's too late.

The Double Asteroid Redirection Test (DART) Mission of 2022 showed that if we had enough time, we could theoretically run a spacecraft into an asteroid and change its orbit enough to deflect it, but for smaller meteors, we'd never spot them soon enough.

The good part of all this is that your chance of being hurt or killed by a meteorite is still way less than a lot of things we take for granted and do just about every day, like getting into a car.  That last bit, though, is why people tend to over-hype the risk; we do that with stuff that's weird, things that would make the headlines of your local newspaper.  (I remember seeing a talk about risk that showed a photograph of an erupting volcano, a terrorist bombing, an airplane crash, and a home in-ground swimming pool, and the question was, "Which of these is not like the others?"  The answer, of course, was the swimming pool -- because statistically, it's much more likely to kill someone than any of the others.)

So it's nothing to lose sleep over.  Unless you're Ann Hodges of Sylacauga, Alabama, who was just trying to take a damn nap for fuck's sake when this stupid rock came crashing through the roof and hit her, if you can believe it.

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