When they used the telescope to create images of the planet, they found an area that appeared dark in light the human eye could see.

VOA: special.2009.08.25

Since Kepler finds planets by measuring the tiny dips in a star's brightness when a dark planet moves across the face of that star, less accurate photometry means Earth-like planets will be too hard to find.

CNN: Kepler or not, we'll find life in space

There was even speculation about a dark material on the tiny planet that could conceivably contain the same organic molecules being hunted on Mars, the carbon-based building blocks that are essential to all life.

BBC: New age of exploration in the hunt for extreme life

The Great Dark Spot seen by Voyager 2, a probe which investigated the planet in 1989, disappeared within a year.

ECONOMIST: Comparative meteorology