Fifty-one years ago, Ann Hodges of Sylacauga, AL became the
recipient of that rarest and rightfully unwelcome of all astronomic gifts—a
meteorite-induced injury. On Nov. 30, 1954, an eight-pound H4 chondrite
meteorite crashed through the roof of her home and ricocheted into her hip,
leaving her with a nasty bruise—but earning her a place in meteorite lore as
the first confirmed modern case of a meteorite directly harming a human being.
Of course, this was hardly the first case of documented
meteorite landings. In fact, 43 years prior to Hodges’ historical injury, a
more famous group of rocks made landfall.
On June 28, 1911, a series of meteorites hit the earth near
Nakhla, Egypt, bearing with them geologic material that originated on Mars.
These so-called Nakhlites have since
become centerpieces in the ongoing scientific debate over the possible past or
future existence of life on Mars.
But scientific conundrums are only part of the fame and
mystery surrounding the Nakhla meteorites—at least as far as space rock
aficionados are concerned. Many sources claim that the Nakhla meteorite storm,
which included a series of atmospheric detonations and earth impacts by more
than 40 extraterrestrial stones, is also an example of that incredibly rare
event: a meteorite fatality!
Unconfirmed reports claim that a meteorite killed a dog
outside Nakhla. However, given that the event occurred nearly a century ago,
it’s unlikely that we’ll ever authoritatively corroborate these claims.
What makes the Nakhla fatality reports so difficult to
believe—and Ann Hodges’ unfortunate luck all the more extraordinary—is the fact
that it’s highly unlikely for a meteorite to strike anyone or anything, let
alone kill something or someone. Thousands of meteorites bombard the earth
every day, but the vast majority are micrometeorites—grains of rock the size of
sand or dust that drift to earth as a result of upper-atmosphere explosions of
Those meteorites large enough to cause injury during impact
are highly unlikely to hit a target as small—and as mobile—as a human being (or
a dog), especially considering that almost all humans reside on dry land, which
covers only about a third of the Earth’s surface. Even in Hodges’ case, the
meteorite crashed into her house and bounced into her while she was napping
(read: an unmoving target).
While there are numerous reports of meteorite-induced death
or injury, many of these erroneously cite scorching-hot, high-velocity
meteorites as the cause of an otherwise unexplained earthbound explosion or
fire—which is extremely unlikely.
WHY ARE METEORITES AN UNLIKELY CAUSE OF EARTHBOUND
EXPLOSIONS OR FIRES?
Why are so-called scorching-hot, high-velocity meteorites an
unlikely cause of earthbound fires and explosions, despite numerous unconfirmed
reports to the contrary?
As opposed to what you may have seen in the movies,
meteorites are not terribly warm when they hit the ground, and some are even
frost-coated. Untrained observers assume that since meteors in the upper
atmosphere are visible due to combustion, earth-impacting meteorites must be
hot as well. The reality is quite the opposite.
First of all, friction causes the combustion visible from
meteors, but it’s friction from air rubbing against air—not air rubbing against
the meteorite. Meteorites strike the atmosphere at speeds of roughly 30,000
miles per hour. At that rate, the air can’t move out the meteorite’s way fast
enough, creating compression in front of it.
This compression heats the air to the point of combustion,
creating the familiar image of a shooting star. But the combustion never
actually touches the meteorite. The compression happens so fast that it creates
a pocket of relatively cool, slow air between the meteorite and the compressed
air, a phenomenon called standoff shock.
The transferred heat literally peels layers off the space
rock as part of a process called ablation.
With the hot layers peeled away, the core of the meteorite remains cool, thanks
to exposure to the vacuum of space. High-altitude air may chill it further once
it slows down enough to shed its combustive fireball.
By the time meteorites hit earth, they’re moving at perhaps
only 200 mph, and they can be as cold as hail or snow. That’s why, contrary to
popular belief, Ann Hodges was in virtually no danger of being burned by her
When meteorites have caused documented damage, such as the
Hodges incident, it’s been because of their speed and mass, not their temperature.
Thus, we have another Hollywood astro-myth exploded in the name of Geek Trivia.
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The Quibble of the Week
If you uncover a questionable fact or debatable aspect of
this week’s Geek Trivia, just post it in the discussion area of the article.
Every week, yours truly will choose the best post from the assembled masses and
discuss it in the next edition of Geek Trivia.
This week’s quibble comes from the November 9 edition of
Geek Trivia, “Before
the age of the Dyna-Soar.” TechRepublic member Rosenthj pointed out yet another corollary aircraft I didn’t have
the space to mention.
“Actually, the Germans experimented with a vertically
launched, manned version of the V-1 concept—though rocket-powered with the same
engine used by the Me-163—called the Natter
(Viper) Ba-349B-1. So this was the first vertically launched, manned,
rocket-powered weapon. See this link for a fascinating history.”
Extra points for the great link, dear reader. To the rest of
you: Keep those quibbles coming!
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The Trivia Geek, also
known as Jay Garmon, is a former advertising copywriter and Web developer who’s
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books, technology, and all things geekish or subcultural.