October 27 – Meteor!

Posted October 27, 2018

A lot of debris from space falls onto the Earth.

And when I say "debris," I MOSTLY do not mean human trash / junk. Space junk like lost equipment, dead satellites, and upper stage boosters is definitely a concern, but most of it is circling the Earth; stuff that gets bumped out of orbit and falls on us often burns up in the atmosphere. Of course, some larger pieces do survive the friction of plunging through our protective layer of air, and NASA claims that an average of one catalogued piece of debris falls somewhere on Earth each day - and has for 50 years now!

But....so far there has been zero big-time problems for people down on Earth from the human-made debris. No significant property damage, no deaths or injuries.

But in space, there is a lot of debris that humans didn't make. I'm talking about all the dust, bits of rock, pebbles, larger chunks of rock and ice, and even boulders or small planetoids. All of this debris is either stuff left over from when the solar system formed or stuff created when comets break up or when rocky or icy bodies collide in space. 

And any of that dust-to-boulder-or-larger stuff that happens to hit the Earth becomes a meteor (a "shooting star") in our skies - lovely streaks of light that are exciting to see.

Rarely does a meteor make it all the way to the Earth's surface, but the larger bits that do are called meteorites. There are meteorites that are mostly made of iron, some that are mostly made of stone, and some that are a mix of stone and iron.

Now - how many meteors and meteorites fall on the Earth? An astounding 37,000 to 78,000 TONS of space debris rains down on Earth EVERY YEAR!

Most of that would come from dust-sized particles that of course burn up in the atmosphere. Phew!

Still, thousands of teeny bits of space rock make it all the way to the Earth's surface every year. Of course, most of them fall into the ocean (which makes up about 70% of the Earth's surface), and a lot of them fall onto empty sweeps of land like Antarctica, Siberia, the Sahara Desert, the forests of Canada and Africa and South America, and so on... 

Most of the Earth is ocean.
Above, the Pacific Ocean as viewed from space.
Below, even the land portions of the Earth are
only partially inhabited.

On this date in 1973, a 3-pound (1.4 kg) meteorite struck the ground in a city - in Cañon City, Colorado, to be specific - a very rare event. It landed on a garage, tearing a 6-inch hole in the garage roof, and leaving a 2-inch gash in the cement floor.

Notice that it didn't hit a car, or a pet, or a person.

In all of history, apparently, only 35 meteorites have ever hit a human-made structure in the United States. And only one person has ever been hit by a meteorite (at least that we know about): a 34-year-old woman napping in her home in Alabama was struck by a nine-pound meteorite. It gave her a big bruise but that was it! Wow!

This "only one person" I'm talking about is the only person known to have been hit by a meteorite anywhere in the world, throughout all of recorded history. (A man in India who was reported to have died in 2016 from an impact of what many presumed was a meteorite was apparently the victim of some sort of land-based explosion.)

However, being hit by a meteorite isn't the only thing to worry about. A really large meteorite can explode in the atmosphere and create a shock wave. In 2013 a 12-ton meteor entered the Earth's atmosphere and broke apart some 20 miles (30 km) above the Russian city of Chelyabinsk. About 1,000 to 1,200 people were injured in that extremely rare incident - but most of the injuries were cuts from glass broken by the shock wave.

I couldn't find any evidence that bits of the meteorite itself struck anyone. I read that 75% of the meteorite evaporated, but 9,000 to 13,000 pounds of meteorite (in varying sizes of chunks) fell onto Earth. The largest fragment was 1,400 pounds, and it broke through ice that was more than two feet thick to fall into a lake, leaving a 23-foot-wide hole in the ice!

But apparently no pets or people were struck by meteorite pieces - and nobody died from their shock-wave injuries. Phew!

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