The world in question is a giant the size of Jupiter known as TrES-2b. NASA's Kepler spacecraft detected it lurking around the yellow sun-like star GSC 03549-02811 some 750 light years away in the direction of the constellation Draco.
The researchers found this gas giant reflects less than 1 percent of the sunlight falling on it, making it darker than any planet or moon seen up to now. [The Strangest Alien Planets]