In desert villages in Chile, 250 families are glad to let the sun roast their goat meat. The UN Development Programme paid $110 for the wood to build each solar oven. Fuel is free; pollution is nil. Women can spend time with kids instead of gathering wood. Solar Cookers International estimates one to two million solar ovens are now in villages, refugee camps, and sunny cities.

Solution: Synchrotron imaging, an x-ray technique more powerful than CT scanning and more precise than grindstone cutting. Over three years, French paleontologists Malvina Lak, Paul Tafforeau, and colleagues have used a synchrotron to sift through 25 pounds of 100-million-year-old amber and find 1,000 fossils, including wasps, flies, and spiders. An x-ray beam penetrates the rock-like drippings and pinpoints the encased specimens, which the team builds up as computerized models and produces in 3-D plastic form.

It began with a book. Not a famous book or a best seller but a science textbook, on the shelf of a community library in Malawi—one of 300,000 volumes donated to locations across Africa through the American Institutes for Research. Using Energy, by Professor Mary Atwater of the University of Georgia, had a picture on its cover that captured a 14-year-old William Kamkwanba's imagination, inspiring him to feats of invention. It was the image of a windmill.

In 2002 Kamkwamba had gone to the library in a stubborn attempt to continue his education. A drought had cut his family's food supply so he couldn't afford the fees necessary to enroll in secondary school. He knew little English and couldn't read most of Using Energy. But being the kind of guy who takes apart broken radios and fixes them, he was able to learn a great deal from the illustrations. He was sure he could build his own windmill using scrap from junkyards—an old bicycle frame, PVC pipes for blades. And he did.

To the amazement of fellow residents in the little town of Wimbe, when Kamkwamba hooked his windmill to a dynamo of the sort used to run a bicycle light off a rider's pedaling, his invention generated electricity.

Soon, Kamkwamba built another windmill to pump water from underground. A newspaper noticed. Then a blogger (although Wimbe did not have Internet access, and Kamkwamba had yet to learn the meaning of the world "Google"). Kamkwanba was invited to a TED conference and then himself became the subject of a new book, The Boy Who Harnessed the Wind, written with journalist Bryan Mealer.

What is a kilogram? It’s 2.2 pounds, of course. Or is it? The kilo is the only basic international standard pegged to a physical object—a 120-year-old platinum-iridium cylinder kept in a vault outside Paris and known as Le Grand K. In recent years scientists noticed slight variations in the cylinder’s weight. They’ve gone into high gear to redefine the kilo as a universal constant based on nature instead of an object vulnerable to distortion.

Quick, what’s faster than a speeding bullet and isn’t named Superman? The answer is the Bloodhound SuperSonic Car, or soon will be. Now being built in England, the jet-and-rocket-powered ride is designed to go, go, go 1,050 miles an hour. If it succeeds, it’ll blast past the current land speed record of 763 miles an hour, set in 1997 by Andy Green in the jet-propelled Thrust SSC. 

Just as gas-powered autos depend on oil, the world’s future fleet of electric cars may well depend on an obscure element now mined in only a handful of places: lithium. Because it is the world’s lightest metal and good at holding a charge, lithium in batteries can deliver the energy electric cars need without weighing them down or requiring frequent recharging stops.

Of all Pisa’s leaning towers—yes, there are several—the famous one is the least likely to topple. That’s because an 11-year restoration effort, involving three years of painstaking soil removal, has successfully steadied the precariously poised campanile. Pisa’s soil is mostly compressible clay and sand, which gives way over time and causes big buildings to shift.

It illuminated the Titanic, discovered hydrothermal vents on the seafloor, even located a lost hydrogen bomb. Now Alvin is ready for a new adventure: a major makeover. After 45 years and 4,500 dives, America’s hardest working, deepest descending submersible is slated for its biggest overhaul since 1973. According to Anthony Tarantino of the Woods Hole Oceanographic Institution, which operates the Navy-owned vessel, the upgrades will occur in two phases over several years, as funding permits. Those changes (left) will let the nimble, small-truck-size sub, which transports a pilot and two scientists, do more things better—like dive four miles instead of 2.8, and survey 99 percent of the ocean bottom versus 63. So don’t think of it as a midlife crisis; consider it Alvin 2.0, retrofitted for 21st-century exploration. —Jeremy Berlin

Click illustration to enlarge.

Art: Don Foley. Photograph by Dan Fornari, Woods Hole Oceanographic Institution

More than a billion people in the developing world need glasses. But opticians aren’t exactly on every block in sub-Saharan Africa. In some places the ratio is one to one million residents. Pondering this problem, Oxford University physics professor Joshua Silver came up with a brilliantly simple solution: a pair of eyeglasses, currently costing about $19, that the wearer can adjust. Silicone oil is injected into a gap between two sheets of plastic until the lens provides sharp vision. The inventor’s field research shows the correction can be better than that of prefab glasses sold at a store.

For centuries sandbags have stopped floods. They can fill in a divot in a dike or stand tall on uneven terrain. But hundreds of volunteers are needed to fill the bags—sometimes funneling sand through an upside-down traffic cone—and to schlep them to build walls. Inventors are devising more efficient devices: plastic modules filled with sand by a front loader, rubber tubes pumped full of water to weigh them down. Don Ward tests these higher-tech options for the U.S. Army Corps of Engineers and says they work well. “I’m amazed we still use sandbags,” he adds.

Photographer Tyrone Turner photographed the March 2009 coverage on energy efficiency and produced a striking set of images using a thermal camera. I had a chance to ask him about the challenges of the assignment.

Alex Trebek is a do-it-yourself host. On a lunchtime break from his duties as chief interrogator for National Geographic’s National Geography Bee on May 20 and 21, he picked up a dictionary and got busy. He had his list of questions (and answers) in a binder. If he saw a name he wasn’t sure how to pronounce—like Jengish Chokusu, a mountain peak on the China-Kyrgyzstan border—he’d look it up and insert diacritical marks to guide his tongue (the accent goes on the middle syllable of Chokusu). A consummate multitasker, he agreed to be interviewed while juggling questions and place names and sipping a glass of wine. “I have to work, so I must be half-tanked,” he joked.

Have you learned a lot of geography from hosting the Geography Bee for 20 years?
I’ve learned some stuff. But I’m not likely to retain the information. Keep in mind I have another program I do based on information that takes up a lot of my available random access memory. [Hosting the Bee] has taught me that many of our young kids are very well informed about the world. But I get to see the crème de la crème.

How would you do in the Bee?
Not particularly well. Any of the kids could beat me.

Most Bee contestants are male – as they are on Jeopardy, right?
There are now more women on Jeopardy than men, though that’s not always been the case. I think we’re about 55/45 women to men. Maybe it augurs well for the Geography Bee.

You’re Canadian. If you had to write a question about Canada for the Geography Bee, what would it be?
Most people don’t realize that this Canadian city lies directly south of a major American city.

Is it … Windsor?
Yes, it is Windsor … and Detroit!

Will there ever be another Jeopardy contestant like Ken Jennings, who won $2.52 million on 74 consecutive shows?
How do you even begin to dream that there is the possibility of another Ken Jennings? There might be, but it took us, what, 20 years to get Ken, and it might well take 20 more years to come up with somebody who will achieve or surpass Ken’s mark. Unless we find some contestant on steroids.

Do you have any favorite place names you get a kick out of saying?
Some names just sound great. Samarkand. In Asia. You cannot say Samarkand without thinking of something exotic. Just the sound of the word: Samarkand.

Any favorite North American place names?
Piscataway, New Jersey. Pis-CAT-a-way. Not PIS-ca-tawee. You drive through New Jersey and you want to exercise your pronunciation skills, just try to correctly pronounce a lot of the Indian place names. Your normal approach to pronounciation is thrown a curve. What’s the one in Florida? Kis-SI-mmee. Looking at it you’d think Lake KISS-a-mee!

It’s impressive that Jeopardy has become such a part of the fabric of people’s lives.
I got a letter recently from someone who told me about his mother dying. She went into a coma. They knew she was on her last hours. And his sisters went in and spent time. And because she had always watched Jeopardy, they turned on the program. One of the clues came up. She opened her eyes, and gave the response. And died. Came out of a coma and said, you know, “What is Panama … whatever.” Boom. Gone. I thought it was an amazing story.

Are you always being recognized by fans who go, “Alex, I’ll take potpourri for $100?
A lady recognized me on the street here in D.C., and she said, “Pat Sajak!”

Think you can match the 11-year-old who won the 2008 National Geographic Bee? Test yourself with the five questions from the championship round, then watch video of the tense final minutes.

-Marc Silver