How Scared Should I Be of Meteors?

The galaxy is teeming with rocks that don't care if we all die. This bothers me a little.

Mike Pearl

Mike Pearl

Technically an asteroid. Illustration by Sarah MacReading

In the column "How Scared Should I Be?" VICE staff writer and generalized anxiety disorder sufferer Mike Pearl seeks to quantify the scariness of everything under the sun. We hope it'll help you to more wisely allocate that most precious of natural resources: your fear.

If you look up at the night sky in the next couple of weeks, your odds are much better than usual of seeing a shooting star or two or seven. That's because we Earthlings are at a point in our annual trip around the sun that takes us through the debris field left by a comet called Swift-Tuttle, which was last seen in 1992. When chunks of that debris hit our atmosphere, they turn into a multi-week light show we call the Perseid Meteor Shower. This is going to be one of the most active Perseid showers in recent memory, making this the most wonderful time of year for your nerdy uncle who spent all that money on time-lapse photography gear.

But like many of the known objects whizzing around our solar system, Swift-Tuttle has a tiny, tiny chance of hitting Earth at some point. That makes the Perseid Meteor Shower a beautiful but horrifying reminder that a high-velocity space rock could take out our little Horton Hears a Who speck. And since its an inanimate object, it wouldn't even give a fuck.

Human extinction wouldn't even require a "Texas-sized" chunk, like the one that probably K.O.-ed the dinosaurs. In fact it's thought that something 60 miles across would probably be enough to extinct humanity, so an object about the size of Jamaica should more than do the trick. But even smaller meteors injure people, and might even kill them. So are collisions with objects from space such a serious danger that building Ned Flanders-style backyard shelters might actually be a rational move?

I took my anxieties to Paul Chodas, who manages NASA's Center for Near-Earth Object Studies at Jet Propulsion Laboratory. Just like C-3PO, he told me the odds of a dangerous encounter with an asteroid, but unlike Han Solo, my spaceship (Earth) probably isn't at any real risk at all. Our conversation has been edited for length and clarity.

VICE: I'm scared of meteors. Should I be?
Paul Chodas: The average person should not be concerned about being injured by asteroids and stuff from space in general because it's extremely unlikely and extremely rare that that sort of thing happened.

I read that a small meteorite killed someone earlier this year. Could that happen to me?
There was a lot of skepticism at the time because the crater that we had seen pictures of is more consistent with something exploding from the ground rather than something meteor impacting. That fatality is not confirmed to be from a meteorite.

Should I be more worried about something like the Chelyabinsk meteor that hit Russia in 2013?
That certainly was a meteor, and it certainly caused injuries; most of those injuries were from the shockwave and the broken glass, because many windows shattered from that impact. It was the shockwave that produced the hazard.

That meteor had the mass of the Eiffel Tower until it hit the atmosphere and started breaking up. Why was no one killed?
[The atmosphere] pulverizes the asteroid and turns 99.9 percent of it into dust, which was the cloud that was photographed in the sky. That's most of the material of the asteroid—what was left over was just a tiny, tiny fraction.

How did an Eiffel Tower-sized object escape your notice?
It approached us from the daytime side of the earth, so when it was close enough to the earth to be bright, it was in the daytime sky, and that's not part of the sky that we can search for asteroids in, we can search for asteroids in the nighttime sky, we look for them as they fly near the earth and they shine by reflected light.

Why doesn't that stealth approach happen more often?
Asteroids are in orbit around the sun, as is the Earth, and we have a chance to discover these asteroids years—or even decades—before they might impact [us], if our search programs are thorough enough, and we're not really, really unlucky.

Really, really unlucky in what sense?
In the sense of one that does not ever pass near the Earth.

Yikes. Can that happen?
That's certainly a possibility. But that would be extremely rare. An example of that orbit would be a long period comet—something which has a very long orbital period. There are many fewer of those than there are of asteroids and these shorter period orbits.

Wouldn't a comet be less dangerous just because of its composition?
It's less dense, yes, but it could be larger and it comes in at a higher velocity so it still poses a hazard. But it's less of a hazard because there are many, many, fewer comets. They are simply not very common, especially those that pass by the earth's orbit. Asteroids are 99 percent of the hazard, really.

Let's talk about Apophis. That object could result in a devastating meteor impact in a few decades right?
It's not a meteor yet. It's an asteroid. It's only a meteor when it's flying through the atmosphere, and glowing. Apophis has a very low possibility, right now, of impacting the earth. Understand that the probabilities change as our knowledge of its precise orbit changes.

What kind of odds does Apophis have of colliding with us?
There's always a little bit of uncertainty. As we refine our estimate of the orbit better and better, our ability to predict the position of the asteroid decades in the future improves, and the range of orbits becomes better constrained. Apophis [is currently predicted to have] a one in 150,000 chance for the year 2068.

I plan to die right around then anyway. But an impact doesn't sound very likely. Are there any objects out there that are more likely to be on a collision course with us?
There are several that we list on our website. But that's how we're talking with these possibilities: very, very small.

Do you know exactly where on Earth Apophis would hit, theoretically?
There's no danger on a particular impact spot when the probability is so small. On the other hand, there have been a few examples of asteroids that we have seen in space, and we could then predict that they could hit the Earth. 2008 TC3 was an asteroid in 2008 that we saw in space and was headed for the earth. We knew it was very small because it was so dim and faint in magnitude, and we were able to predict within a few hours of tracking where it would hit on the earth. That's the one that hit in Sudan in the Nubian Desert.

I read that the Nubian meteor was about four meters. Big ones like that are rare right?
There are exponentially more as you go to smaller and smaller sizes. So, what that means is, the number of potential impacts would be greater on the smaller sizes than the larger sizes. The Chelyabinsk size was about 20 meters. We believe that an object of that size is going to impact the earth about once every 50-80 years or so.

What about the odds of something bigger than Chelyabinsk, but maybe not big enough to wipe out humanity?
A 100 meter object might hit once every ten thousand years, and a 200-meter object might hit once every 30,000 years.

Couldn't a once-every-30,000-year object sneak up on us, like the Chelyabinsk meteor?
The larger ones are easier and easier to find in our telescopes on previous passages by the earth. We should be able to discover, let's say a 300 meter object, many years, if not decades before it poses a problem. [Objects that size] are easier to find, and we have a chance to do something about it. [We] think we could divert them, given sufficient warning.

By sending an oil drilling crew, like in Armageddon?
No, we would send a smaller space craft to hit the asteroid as JPL (NASA's Jet Propulsion Laboratory) and NASA did for Deep Impact, the mission that hit the comet nucleus 10 years ago. So we have the technology to hit a small body in space and we could do that to a hazardous asteroid, given sufficient warning.

Final Verdict: How Scared Should I Be of Meteors?

1/5: IDGAF

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