Scientists Discovered a Planet Made Entirely of Diamond Twice the Size of Earth

About 40 light-years from Earth, in the constellation of Cancer, orbits a planet so strange it sounds like fiction. 55 Cancri e is approximately twice the diameter of Earth, eight times its mass, and so close to its star that one orbit takes only 18 hours.

Spectral analysis of its host star showed it is unusually rich in carbon. If the planet formed from the same materials, scientists at Yale University calculated that up to a third of its mass could be diamond — primarily a thick mantle of crystalline carbon under enormous pressure.

Conditions on the Planet

• Surface temperature: 2,400°C — hot enough to melt iron
• Day side: Likely covered in lava oceans
• Year length: 18 Earth hours
• Surface gravity: About double Earth's
• Composition: Carbon, silicon carbide, iron — and diamond

How Much Diamond?

If the diamond mantle theory holds, 55 Cancri e contains more diamond than humanity has ever mined — by a factor of approximately 10²² (10 sextillion). The economic value, were it accessible, would be larger than every economy on Earth combined to a degree that breaks the concept of "value."

Reaching It

At our fastest current technology, getting there would take roughly 700,000 years. The diamond planet remains, for now, only a glimpse through a telescope — and a reminder that the universe contains worlds stranger than any human imagination.