An anonymous reader writes: Astronomers from Stanford and the Kavli Institute have discovered a new exoplanet orbiting 51 Eridani that strongly resembles a young Jupiter. They say its similarities could help us to understand how our own solar system formed. It's a convenient discovery, because 51 Eridani is less than 100 light-years away, and only about 20 million years old. The discovery was confirmed by astronomers at the Keck Observatory and published in Science (abstract). "In addition to being the lowest-mass planet ever imaged, it's also one of the coldest – 800 degrees Fahrenheit, whereas others are around 1,200 F – and features the strongest atmospheric methane signal on record. Previous Jupiter-like exoplanets have shown only faint traces of methane, far different from the heavy methane atmospheres of the gas giants in our solar system."