5 Most Incredible Discoveries of the Week Including new insights into tail wags and dark matter By Newser Editors, Newser Staff Posted Nov 2, 2013 5:23 AM CDT 0 comments Comments (Shutterstock) (Newser) – Expressive tail wags, a hot new planet, and some new species highlight this week's discoveries: How Dogs' Tails Speak Volumes: Wagging tails are little more complicated than you might think. A new study finds that dogs are able to pick up on friend or foe depending on whether a tail is wagging to the left or right. But Fido apparently isn't intentionally communicating. Earth-like Planet Discovered, but It's Hotter Than ... Astronomers have discovered a planet where a certain red guy with horns could make himself right at home. It's a planet much like our own Earth—about the same size, with the same mixture of rock and iron, and it orbits a star like our sun—except that Kepler 78b is an infernal ball of fire. Think temperatures up to 5,000 degrees Fahrenheit, hot enough to melt rock. 'Lost' Rainforest Yields Bizarre Species: Meet the blotched boulder frog, the shade skink, and the leaf-tailed gecko, three new species discovered when researchers finally got to explore a rainforest nearly impossible to reach in Australia. Dark Matter Experiment Finds Best Nothing Yet: The team running the biggest, most sensitive dark matter detector yet announced its first round of results this week—specifically, the lack thereof. Scientists cooled a vat full of liquid xenon to minus 150 degrees Fahrenheit, watched it for three months, and caught nary a glimpse of the particle clouds that should have theoretically shown up. Turns out, this is a good thing, scientifically speaking. Yellowstone's Magma Reservoir Bigger Than Thought: That Yellowstone has a big blob of molten rock lurking beneath it isn't news to scientists. A new analysis, however, shows that this blob is more than twice as big as they originally thought. Figure about 50 miles long and 20 miles wide, though researchers aren't much worried about an eruption. Click to read about more discoveries, including a new dolphin species.