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JUDY WOODRUFF: It's not just in sci-fi movies. Asteroids really are moving closer to Earth more frequently and chunks of them are hitting too.
The one that caught everyone's attention struck last February, when a meteor hit near the Russian city of Chelyabinsk. It was only 60 feet wide, but injured more than 1,200 people.
New research about that meteor and other asteroids was published yesterday. Experts say fragments are hitting 10 times more often than known before.
NewsHour science correspondent Miles O'Brien fills us in.
Miles, hello there.
So what was it about this incident in Russia that has caused scientists to believe that these rocks may be hitting Earth more often?
MILES O’BRIEN: Well, it was interesting because this one really caught everyone by surprise. It came from the direction of the sun, and so nobody saw it coming.
What was also interesting about it was, there were a lot of dashboard cameras and CCTV cameras that captured it. And so scientists became much more fascinated by this than they have in previous cases because they had so much documentary evidence. As they looked at it and its size, they started asking the question, how frequent are these events really?
And when they looked at the sensor data used to guard against above-ground nuclear testing over the years, they identified what may be many more strikes like these, perhaps over the ocean, perhaps over an unpopulated area over the course of the past century or so. And so that leads them to believe these are much more common than we thought.
JUDY WOODRUFF: So, how much more common?
MILES O’BRIEN: Well, on the order of 20 to 30 years, as opposed to once every century.
Now, this thing was 60 feet long, weighed 10,000 tons and was moving about 60 times the speed of sound. It came down. It was brighter than the sun. So while it's small relatively, it's a pretty scary thing, and it caused a lot of damage on the ground, caused some injuries. Fortunately, no one died.
JUDY WOODRUFF: Are scientists saying how then -- and now that they have done this research, how worried are they saying people should be?
MILES O’BRIEN: Well, they're not losing sleep at night, but it does call into question what we should all be doing about it.
We have done a pretty good job in recent years looking for the really big rocks, the kilometer-size rocks, the ones that would do to us what a rock did to the dinosaurs 65 million years ago. We have identified about 95 percent of those. As the rocks get smaller, they can still cause a lot of damage. They could take out a city, for example, or in this case cause a lot of ground damage just by the shockwave.
We don't have the infrastructure to spot these smaller asteroids. And so there's a lot of talk about the United Nations getting involved, the space agencies in the world getting involved. And even one private foundation, the B612 Foundation, wants to launch a satellite that would hover out near Venus that would be able to see smaller asteroids, including those that we can't see because the sun's in our eyes.
JUDY WOODRUFF: So, how much of that that they're talking about doing is actually under way now?
MILES O’BRIEN: Well, there's talk about it right now.
There's a growing realization of the threat. And the Chelyabinsk event certainly crystallized a lot of these thoughts. But the sad fact is, you know, we haven't really gathered together the nations of the world to do a concerted effort and really focus on this problem.
Just look at the moon. Look at all the pocks in the moon. That's what happens when you don't have an atmosphere and you don't have tectonic movements to cover over the asteroid impacts. Basically, we're in the same neighborhood. It's a rough neighborhood. We're going to get hit by a rock one of these days if we don't watch out.
And if we can identify them and we have enough advanced warning -- I'm talking about decades -- we have the technology to go out there and nudge it out of our way and ensure that we don't go the way of the dinosaurs.
JUDY WOODRUFF: But -- but you're saying only if we have enough warning?
MILES O’BRIEN: We need the warning. We do. I mean, we can send a nuclear weapon out there and nudge it off.
There's all kinds of ways of attaching perhaps a rocket motor to an asteroid headed in our direction. It only needs to be perturbed just a little bit if you know decades in advance. The closer they are to us, the bigger a problem it can be. And so that's why it's important we keep looking.
JUDY WOODRUFF: So, Miles O'Brien, thank you. I don't know how many of us are going to sleep soundly tonight.
(LAUGHTER)
MILES O’BRIEN: I feel like Chicken Little.
JUDY WOODRUFF: Thank you.