Impact! by Elizabeth Rusch

Author:Elizabeth Rusch
Language: eng
Format: epub
Publisher: Houghton Mifflin Harcourt

This map of the solar system shows the orbits of the 1,400 Potentially Hazardous Asteroids (PHAs) that were discovered by 2013. Sky surveys have discovered many more since then.

At 1:15, the follow-up photos on the weird streak come in. As Eric scans the four photos, the white dot seems to move across the screen to the beat of the blaring music. The object is circling the sun. And it’s about thirty-three feet (10 m) or so wide—the length of a school bus. “I want to observe this until I can’t observe it anymore because this thing is quite close to us,” Eric says.

To be considered a potentially hazardous asteroid (PHA) an object must have an orbit that brings it close to Earth, within 0.05 astronomical units (au) or about 4.6 million miles (7.5 million km). At roughly 435,000 miles (700,000 km), the object is definitely in range. But PHAs also have to be large—460 feet (140 m) wide. And this one is likely a mere thirty-three feet (10 m).

Then Eric finds an object even closer, about halfway to the moon. “It’s not going to hit, not on this pass anyway,” he says. “But at less than lunar distance, if the orbit changes even slightly, it could bend into an impacting orbit.” In fact, the most likely fate of this object is that it will hit Earth. “Give it a million years and I can almost guarantee it,” he says.

At 2:17 a.m. Eric gets an email from the observer at one of the other Catalina telescopes who just found a really bright object. From its brightness and its distance from Earth, Eric estimates the size of this object at about sixty-five feet (20 m)—twice as big as the one he found earlier. This could pack a Chelyabinsk-size punch! Eric reports the asteroid right away so people around the globe can start tracking it.

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