How dark is dark within the solar system? We suppose black holes, by their very nature, are pretty dark. But high on the list of astronomical objects that don’t reflect much light is a new contender: TrES-2b, a Jupiter-sized gas giant around 750 light-years from Earth that’s now taking top billing as the darkest exoplanet that astronomers have ever discovered.

Brightness readings measured by NASA’s Kepler spacecraft suggest that TrES-2b reflects less than one percent of the sunlight that hits it – and that’s coming from a star a mere three million miles away from the planet itself (GSC 03549-02811). For comparison’s sake, Earth is around 93 million miles from the sun and, we should note, a whole lot cooler. The average temperature of TrES-2b hovers around 1,800 degrees Fahrenheit.

Although the super-heated planet’s atmosphere is full of light-absorbing chemicals, there’s no indication that their presence is the direct reason why the planet fails to reflect a great deal of light.

‘It’s not clear what is responsible for making this planet so extraordinarily dark,’ said Princeton University professor David Spiegel, co-author of the paper that first reported the planet’s existence. ‘However, it’s not completely pitch black. It’s so hot that it emits a […]