'Diamond Planet' Twice Earth's Size Discovered

Scientists have discovered a planet largely made of diamonds orbiting a nearby star, about 40 light years away from Earth.

The planet named as "55 Cancri e" is twice the size of Earth and eight times its mass, reveals a new study led by Yale University scientists.  

It is one of the five planets orbiting the sun-like star called "55 Cancri." Experts have classified the planet as "super Earth," which orbits the sun-like star in just 18 hours. The planet is in the constellation of Cancer, but is visible to the naked eye in the night sky.

Diamond planets have been spotted earlier, but this is the first time that a diamond planet bigger than the Earth orbiting a sun-like star has been discovered.

"This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth," lead researcher Nikku Madhusudhan, a Yale postdoctoral researcher in physics and astronomy, said in a statement.

"The surface of this planet is likely covered in graphite and diamond rather than water and granite," he said.

The planet is extremely hot with its surface temperatures reaching 3,900 degrees fahrenheit.

Based on assumptions that the chemical composition of the planet is similar to Earth, astronomers thought that the diamond planet has considerable amount of water. But the new study suggests that the planet does not have water at all.  

When the experts studied the host star's composition, they found that the rocky planet is mainly composed of carbon (as graphite and diamond), iron, silicon carbide, and some silicates. According to them, at least one third of the planet's mass could be diamond.

"By contrast, Earth's interior is rich in oxygen, but extremely poor in carbon - less than a part in thousand by mass," co-author of the study and Yale geophysicist Kanani Lee, said in a statement.

This could mean that the planet can no longer be assumed to have atmospheres and chemical constituents similar to Earth. But the presence of rich carbon might suggest that the planet has different thermal evolution and plate tectonics, which could create seismic activity, volcanism and mountain formation.

The discovery will help scientists to study the geochemistry and geophysical processes in Earth-sized alien planets.

The findings of the study are published in the journal Astrophysical Journal Letters.