5 Most Incredible Discoveries of the Week Including just the second asteroid ever spotted before hitting Earth By Newser Editors, Newser Staff Posted Jan 4, 2014 5:59 AM CST 1 comment Comments The moon lights up the observatory containing the Schulman telescope on Mount Lemmon, near Tucson. (Shutterstock) (Newser) – An amazing find by a sharp-eyed astronomer and a bizarre discovery about the pooping habits of dogs are on this week's list: For 2nd Time Ever, We Saw an Asteroid Before It Hit Us: While working a solo shift on New Year's Eve, an Arizona astronomer spotted a car-sized asteroid en route to Earth. There are a few amazing things about this: 1) It's only the second time ever that an asteroid has been spotted before impact, and 2) The previous one was spotted by the same guy. Dogs Use Earth's Magnetic Field to Poop: There's a reason why dogs position themselves just so before doing their business, say scientists. Rover and friends just might be getting in sync with the Earth's magnetic field—and in a very specific way. Ancient Obelisk's True Purpose Revealed: Researchers using 3D modeling and data from NASA think they've discovered the true purpose of the Obelisk of Montecitorio—upending a theory that has stood for decades. The 71-foot-tall ancient Egyptian obelisk was brought to Rome by Emperor Augustus, but it seems he was paying homage to Apollo, not himself. Ancient Diamonds Aren't Exactly Diamonds: Back in 2007, a team of researchers said they'd found 4.3-billion-year-old diamonds inside zircon crystals taken from Australia's Jack Hills. But those researchers had used a grinding paste made of synthetic diamonds to polish the zircons in preparation for lab tests, and that apparently led to a big mistake. China's 'Great Wall' Wasn't Its First Great Wall: As NPR tells it, archaeologist Gary Feinman was "simply walking around eastern China's Shandong province" on a hunt for pottery shards when he found something much, well, greater: a rammed earth wall that reached as high as 15 feet in places. Then he decided to map it, and things got really interesting. Click for more incredible discoveries.