Asteroid Watch

Asteroid Watch Eros
Photo Credit: NASA

Citizens can now track nearby asteroids online or via Twitter.


Keeping tabs on nearby asteroids. I'm Bob Hirshon and this is Science Update.

For years, NASA has been tracking asteroids and comets flying near earth, to make sure nothing gets too close. Now, you can keep up with their sightings with the new website Asteroid Watch. Project manager Don Yeomans of NASA's Jet Propulsion Laboratory says it's all laid out in plain language.

Still, it's accurate and up-to-date, and we have news notes, we have a widget that you can download that gives the next five close approaches of asteroids to the earth, there is a Twitter feed you can take advantage of...

... This may sound anxiety-provoking, but Yeomans hopes it will actually reduce fear—by showing that NASA's on the ball, and that even nearby asteroids almost never pose a threat. What's more, since NASA can predict an object's path up to a century in advance, we should have ample time to thwart a potential collision if we spot one. I'm Bob Hirshon for AAAS, the Science Society.

Making Sense of the Research

Every day, more than 100 tons of space debris hits the earth. Fortunately, almost all of this is made up of very small particles or dust, and much of it burns up as it enters our atmosphere. Occasionally, somewhat larger chunks of rock fall to the ground—rocks the size of a grapefruit, for example—but because most of the planet's surface area is covered by oceans and thinly populated land, we don't even notice most of these. 

In much rarer cases, much larger objects collide with earth, and these impacts have the potential to be catastrophic. When a large object that size enters earth's atmosphere, it can set off a nuclear bomb-sized explosion, with secondary effects like wildfires, earthquakes, and giant tidal waves ripping around the globe. Some scientists now blame an asteroid impact for the extinction of the dinosaurs 65 million years ago; a 110-mile-wide underground crater in Mexico provides evidence for that event. More recently, in 1908, a massive explosion over Siberia, in northern Russia, destroyed over 80 million trees over 800 square miles' worth of forest. Research indicates that the explosion came from a collision with a relatively small comet, made of dust and ice. Luckily, the area it affected was mostly uninhabited. Had the comet struck just 47 minutes later, it would have wiped the large city of St. Petersburg off the map.

Many movies and TV shows—most recently, the TV movie "Meteor"—have imagined the end-of-the-world devastation that would result from a major impact today. The potential for disaster is not lost on the scientific community, especially since 1994, when scientists watched comet Shoemaker-Levy crash into the giant gas planet Jupiter, leaving scars that could be seen for months. (In July 2009, another, unidentified object hit Jupiter, leaving a black spot the size of the Pacific Ocean.) That's why NASA began tracking "near-earth objects" shortly after Shoemaker-Levy hit. 

So, NASA-JPL created "Asteroid Watch" to make the tracking more accessible to the average person. As Yeomans says, the goal isn't to scare the daylights out of everyone. Rather, they hope that by making the information easier to keep up with and understand, they'll be able to reassure people that NASA is aware of the objects coming near us and that the chance of a destructive impact is extremely low. In fact, as of this writing, none of the objects identified by NASA is expected to come dangerously close to earth. And if they ever do find one, they'll have up to a century to prepare for it. In fact, NASA has already developed several concepts for destroying a rogue asteroid or comet, or at least knocking it off course, before it gets too close for comfort. 

Now try and answer these questions:

  1. What is "Asteroid Watch"?
  2. Why is NASA tracking near-earth objects?
  3. What is the benefit of making this information easily accessible?
  4. What are some possible dangers of ignoring the potential threat of near-earth objects? What are the potential dangers of exaggerating the threat?

Going Further

For Educators

The National Geographic Interactive feature Asteroids and Comets explores asteroids, meteors, and their impact on earth.

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