Kepler Telescope

The Kepler space telescope, shown here in an artist’s rendering, helped detect a carbon-black planet. Credit: NASA

Planetary science

A planet the colour of charcoal

Giant world traces a speedy orbit around its star.

A hot and gaseous planet orbiting a distant star is one of the darkest ever found.

Astronomers led by Teo Močnik at Keele University, UK, used NASA’s Kepler telescope to study a star called WASP-104, which lies roughly 144 parsecs from Earth in the constellation Leo. Earlier observations had documented a dimming of WASP-104’s light every 1.76 days, indicating that a planet was regularly crossing the star’s face. But Močnik’s team could not detect starlight reflecting off the planet, as scientists usually expect after discovering a new world. That led the researchers to conclude that the planet is nearly pure black in colour.

The planet’s darkness could help scientists to test their ideas about exoplanetary atmospheres, such as how clouds might form on a world that reflects so little light.