What if a Perseid hit my house?

August 7, 2008 9:26 PM

The Perseid meteor shower is almost upon us and my kids and I were wondering what effect a golf ball-sized meteorite would have if it fell on a two story wood frame house. Any ideas?
posted by salishsea to science & nature (14 comments total)

Not a lot. Much of the meteor's kinetic energy would be exhausted. Larger meteors have hit houses and cars with only minimum, localized damage (hole in roof, hole in car) but no fireballs or explosions or anything else dramatic.

The most famous recent meteor hit was the 1992 Peekskill meteorite which clobbered an unfortunate Oldsmobile. That meteor was about bowling ball size.

Of course, much of a meteor's velocity depends on it's angle of entry into Earth's atmosphere. A shallow entry means that the meteor will travel through more atmosphere, thus slowing it down. A straight on entry would allow the meteor to maintain more velocity, and thus do more damage on impact.
posted by wfrgms at 9:51 PM on August 7, 2008

Oh, I should also add that the composition of a meteor probably matters too. The Peekskill meteorite had a rocky and less dense composition - iron meteorites (my favorite because they are the mysterious cores of planetoids which coalesced but then were torn apart in the violence of the early solar system, and were also the first types of iron used by humans) are much more dense.

Any good rock shop will have some meteorites that you can handle. You should take the kids. A meteorite is the oldest thing they will ever hold in their hands.
posted by wfrgms at 10:01 PM on August 7, 2008

...thank you...and of course I mean what if a METEOR hit my house...
posted by salishsea at 10:01 PM on August 7, 2008

..or maybe I do mean meteorite after all...sigh.
posted by salishsea at 10:03 PM on August 7, 2008

This guy calculated that the terminal velocity of a golf ball is just under 32 meters per second, which is only about 70 mph. So it seems like the impact itself wouldn't cause very much damage if the meteorite has the same mass as a golf ball and doesn't happen to be made of depleted uranium or something.

I'd think the other question would be whether the temperature of the meteorite would be great enough to ignite a fire. According to Wikipedia (no citations, I'm not sure how reliable this is) most of the heat of reentry comes from the shock wave created rather than friction, so that the temperature depends on the speed of the object when it hits the atmosphere. So it would seem that only on a case-by-case basis could you figure out whether a particular meteorite would be hot enough to start a fire.

But hmmm, maybe you'd have to take into account cooling? It seems like a small enough object might cool down by the time it reaches the surface, no matter what its initial reentry temperature would be. And that will depend alot on the shape of the object. I Googled for "aerodynamic cooling" but didn't find anything easily applicable, but my guess would be the mathematics will be complex.
posted by XMLicious at 10:06 PM on August 7, 2008

32 meters per second

Stuff falls at 9.8 m/s² so that's about 3 seconds' worth of falling. . .

Revisiting my notes from Physics 8A from 1985, I now remember that the equation for distance travelled from a motionless start is 0.5 x 9.8ms^-2 x t² = dropping the meteor(ite) from a height of ~150' above the house.
posted by yort at 10:21 PM on August 7, 2008

A lot of it would depend on what it was made of. If it was iron (and some are), it would be a heck of a lot more dense than a golf ball and would hit at a much higher velocity. Even if it was rock, it would weigh somewhat more. (If it was ice, it probably wouldn't make it to the ground.)
posted by Class Goat at 10:33 PM on August 7, 2008

This sounds like a great question for Cornell University's Ask an Astronomer.

For instance, you can be reasonably sure that it won't set the house on fire: Are meteorites hot or cold when they hit Earth?
posted by zamboni at 10:42 PM on August 7, 2008

Nitpick yort, but the force of drag varies directly with velocity (for a given coefficient), so it would take longer to reach terminal velocity than the 3 seconds accelerating at 9.8m/s^2, and thus have to be dropped from higher than 150'. But its probably as good an estimate as any for thinking about the impact

My guess is that depending on how your house was framed & where it happened to hit, it'd either go through the roof and end up in your attic or hit a beam, maybe damage it, and roll off. Either way, you'd get a meteorite out of it, which would be sweet.
posted by devilsbrigade at 12:09 AM on August 8, 2008

The Perseids are caused by tiny specks of ice and dust that burn up in earth's outer atmosphere while travelling at over 100,000 mph, so while it might be fun to think about a meteor hitting your house, if that ever were to happen, it won't be from the Perseid shower.
posted by longsleeves at 12:23 AM on August 8, 2008

This guy calculated that the terminal velocity of a golf ball is just under 32 meters per second, which is only about 70 mph.

But a meteorite might not have slowed to its terminal velocity by the time it hits the ground.
posted by Mr. President Dr. Steve Elvis America at 5:11 AM on August 8, 2008

Here's a photo of a meteorite and the car seat it supposedly hit.

longsleeves is right that shower meteors don't reach the ground. Showers happen at the same time every year because the earth passes through the orbit of a comet, and comet detritus is pretty flimsy stuff. (We have, with great effort, collected some.)
posted by fantabulous timewaster at 6:55 AM on August 8, 2008

Well, according to the Simpson's....
posted by cjorgensen at 7:23 AM on August 8, 2008

Wow the Peekskill Meteorite (picture and more info)! I grew up about 15 miles north of Peekskill. I was in LA on this date but it seems such a big event that I can't believe my parents never mentioned it. It had to have gotten a lot of local coverage.
posted by spicynuts at 8:57 AM on August 8, 2008