Kepler 10b, in all its fiery glory, is not the hottest exoplanet we've discovered. Depicted here is an artist’s depiction of HD 149026b, a “hot Jupiter” that clocks in at a scorching 3,700 degrees Fahrenheit, making it three times hotter than our hottest planet, Venus. How hot is it? “The planet is so warm that astronomers believe it is absorbing almost all of the heat from its star, and reflecting very little to no light,” says NASA. This almost makes this planet the blackest, or darkest planet in the known universe. The planet, which was observed by the Spitzer Space Telescope, is believed to be much cooler on its dark side. Because the planet appears to be “tidally locked” to its sun — just as our moon is locked to the Earth — one spot on the planet is under constant heat.