Each week our friends at Inhabitat recap the week's most interesting green developments and clean tech news for us -- it's the Week in Green.

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Happy Earth Day! In honor of Earth Week, this week we took a moment to think about the origins of this now-global event, exploring why we need Earth Day and how our society can possibly tackle the 7 biggest threats to our environment. If haven't yet made plans for Earth day make sure to take a look at our list of 10 Earth Day activities. One of the major themes of Earth Week this year was lighting, as green lighting innovations ranging from the useful to the absurd made it onto Inhabitat's radar screen. On the more practical end of the spectrum, we reviewed the SUNNAN, Ikea's solar-powered desk lamp, and although we found it to be a bit dim, it actually outperformed its expected charge time. On the lighter side, Randy Sarafan, the same guy who designed a chair that tweets his own farts (seriously), unveiled a lamp that shuts off whenever you shut your eyes. The downside: In order for it to work you have to attach electrodes to your face, which are plugged directly into the wall. Thanks, but we'll pass. And for those who prefer regular, old-fashioned lights, Philips launched its much-anticipated L-Prize winning 10-watt LED bulb on Earth Day. At $60 a pop, you might have to take out a second mortgage to replace every bulb in your home, but you'll recoup that money back on your energy bill, and Philips also announced some rebates to ease the pain.

Speaking of illuminating green designs, this week we brought you a first look at the best new products from Milan Design Week. The MOST exhibition was one highlight of the week, featuring Tom Dixon's flat-pack Stamp Lamps -- and he even invited visitors to design their own lamps using 3d modeling software. We also spotted several eye-catching furnishings made using surprising new materials and processes -- Jolan van der Wiels unveiled a series of 'Transnatural' stools shaped by magnetic fields, Mauricio Affonso blew minds with a transforming table that shifts from a circle to a rectangle in seconds, and Raul Lauri debuted his Decafé Lamp, which is made from recycled coffee grounds. Meanwhile, iBamboo launched an electricity-free iPhone speaker made from a single piece of bamboo.

In green transportation news we've been tracking everything from wooden bikes to biomethane delivery trucks, to 4,000 mph vacuum transport tube transit systems. Last week, Ford announced that the 2012 Focus Electric would be the pace car at the Richmond 400, making it the first all-electric pace car to ever lead the field for a NASCAR Sprint Cup Series race. For green-minded drivers everywhere, eBay launched its new eBay Green Driving site, which promises to help shoppers research and buy fuel-friendly vehicles. We also caught wind of Axalko's stunning bike frames that are made from ash wood. And with Olympic organizers seeking to put on the greenest games ever, UPS added 10 big biomethane diesel trucks to its dedicated 2012 London Olympics fleet. That's a good way to go from brown to green.

In green building news, we shined the spotlight on NASAs new Sustainability Base (which is packed with technology developed for the International Space Station). We also spotted a wedge-shaped building at the Tokyo Institute of Technology that is completely covered in 4,500 solar panels, which enables it to use half of the energy of a similarly-sized building. We also heard about a nifty acoustic wind pavilion in London that makes music whenever the wind blows. And in one of the week's more unusual stories, we reported on a public housing extension in Italy that was made from plastic shopping bags and other bits of non-renewable packaging.

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