Science

It sounds like a horror story: Every few years, usually in the winter months, residents of the town of Leesburg, Va., come home from work to find their backyards overrun with turkey vultures. Not just a few birds, but hundreds of them. Everywhere.

Lt. Jeff Dube is with the town's police department. For a whole week, he spent every evening driving around town, looking for the latest vulture hotspots.

"They like Leesburg. There's really no rhyme or reason. Every three to five years they come back en mass, like this year, 2- to 300," Dube says.

Toyota and BMW have formed an alliance to work on fuel cell cars. So have Daimler, Ford, and Nissan, with hopes of having cars on the road by 2017. But why now, and what obstacles still stand in the way? Jennifer Kurtz discusses the current state of hydrogen fuel technology.

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JOE PALCA, HOST:

This is SCIENCE FRIDAY; I'm Joe Palca. Do you ever get the feeling you're being watched? These days if you're not careful, your phone knows where you are, and there's a good chance somebody else does, too. Or you've noticed that the ads on sites you visit are starting to look a little too personalized, like how did they know I was planning a vacation to New Orleans.

Transcript

JOE PALCA, HOST:

This is SCIENCE FRIDAY. I'm Joe Palca.

You know the theory that a big collision, a comet or an asteroid, something like that, helped kill off the dinosaurs? The idea has been around for a while. But this week, new research published in journal Science provides more accurate dates for the giant impact and the dino demise.

We spend a lot of time sleeping (roughly one-third of our lives, according to the National Institutes of Health). But how much downtime do our brains really need? Experts discuss the links between sleep, memory and cognition, and why our sleep patterns change as we age.

An asteroid the size of an office building will zoom close by Earth next week, but it's not on a collision course, NASA says.

Still, some people think this near-miss should serve as a wake-up call.

"It's a warning shot across our bow that we are flying around the solar system in a shooting gallery," says Ed Lu, a former astronaut and head of the B612 Foundation, a nonprofit dedicated to protecting humanity from asteroids.

The asteroid known as 2012 DA14 was first spotted last year by astronomers in Spain. It's thought to be about 150 feet across and made of rock.

Iran's government on Thursday made clear it has no interest in direct talks until the U.S. eases sanctions that have been squeezing Iran's economy. But the Obama administration isn't budging and says the ball is in the Iranians' court.

The suspicion that Iran wants to make a nuclear weapon is the rationale for the sanctions as well as for veiled threats of U.S. or Israeli military action if those sanctions fail.

Before they end up filleted and sautéed on your dinner plate, salmon lead some pretty extraordinary, globe-trotting lives.

After hatching in a freshwater stream, young salmon make a break for the ocean, where they hang out for years, covering thousands of miles before deciding its time to settle down and lay eggs in their natal stream.

So how do these fish find their way back to their home river?