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Another Day, Another 'Close Call' Between Earth And An Asteroid


In most situations, 745,000 miles would be considered a great distance. That's how far you travel if you went to the moon and back and then one more time to the moon. But when an asteroid the size of two football stadiums comes within 745,000 miles of the Earth, it is ready for its close-up. And an asteroid called 2004 BL86 is visible in the night sky this evening all across the country. And this is of special interest to Paul Chodas, manager of the Near-Earth Object Program at the Jet Propulsion Laboratory in Pasadena, Calif. Welcome to the program

PAUL CHODAS: Thank you.

SIEGEL: You're studying near-Earth objects. Is this asteroid really unusually near the Earth?

CHODAS: It certainly is. And not only that, it's on our list of potentially hazardous asteroids. It's those asteroids that can come really close to the Earth. Although, three lunar distances is about as close as this one can come.

SIEGEL: Just 745,000 miles?

CHODAS: Yeah, astronomically speaking, that's just a skip and a jump.

SIEGEL: So it poses no danger to us, the fact that it's this close?

CHODAS: No, not at all. We've been tracking this for 11 years now, and we know that it can't come closer than that anytime soon. But it's worth keeping an eye on, because over the millennia, it may eventually be able to migrate into an orbit that could intersect the Earth's orbit.

SIEGEL: Your sense of long-term is different from most of us in terms of when we think of long-term.


SIEGEL: What can you learn and what can other scientists learn about this asteroid from its close pass? Well, we get a chance to see an asteroid really up close and personal here. Large telescopes will be taking a close look at it to get its spectrum, to find out about its composition - and especially radar. We'll get a great view of this asteroid, and we get an idea of its shape, its size, how quickly it's rotating. We get an idea of whether or not it has a moon. We get an idea of what its surface is like, whether it has boulders on its surface. So we're learning a lot about asteroids, and we're learning a lot about how they form. And that tells us, really, how the whole solar system formed.

SIEGEL: Now, who will be able to see the asteroid this evening? What kind of equipment do you need?

CHODAS: You need a really good pair of binoculars or a small telescope. This thing is bright for an asteroid, but it's still a challenging object. You will also need a good star chart because the asteroid is moving, so from minute to minute, it will in a different place. And, by the way, this evening is the best time to see it, when it's brightest. Tomorrow evening it will have faded considerably.

SIEGEL: And are you thinking about the possibility of an asteroid like this one or even larger actually someday posing a threat to the Earth? And if so, do we know what we would do to deflect it?

CHODAS: Well, certainly that's part of the reason that we're hearing so much more about asteroids these days. NASA has funded surveys that are searching for asteroids that could pose a hazard of collision with the Earth. If one should be on a collision course with the Earth, we would like to find it early, that is to say years and years ahead of time - much like this one, you know, a decade ahead of time. And if we did find it that early, we could do something about it. We could launch a spacecraft, for example, to collide with the asteroid and just change its trajectory enough that it would miss the Earth years later.

SIEGEL: Would that have saved the dinosaurs if we had been able to deflect that asteroid?

CHODAS: Yes, the dinosaurs didn't have a space program, and they could not deflect that asteroid coming in. They didn't even know about it. But, yes, if we had enough time - that was a large asteroid that - on the order of six miles across, so it was quite a bit larger than this one that caused global devastation back 65 million years ago.

SIEGEL: Well, Paul Chodas, thanks a lot for talking with us.

CHODAS: Thank you.

SIEGEL: Paul Chodas is manager of the Near-Earth Object Program at the Jet Propulsion Laboratory in Pasadena, Calif. Transcript provided by NPR, Copyright NPR.

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