55 Cancri E: The Planet Made Out Of Diamond

55 Cancri e is an extrasolar planet orbiting the Sun-like star 55 Cancri A.

Its mass is about 7.8 Earth masses and its diameter is about twice that of Earth's, thus classifying it as the first Super-Earth discovered around a main sequence star, predating Gliese 876 d by a year.

It takes less than 18 hours to complete an orbit and is the innermost known planet in its planetary system. 55 Cancri e was discovered on August 30, 2004.

However, until the 2010 observations and recalculations, this planet had been thought to take about 2.8 days to orbit the star. In October 2012, it was announced that 55 Cancri e could be a carbon planet.

55 Cancri e receives more radiation than Gliese 436 b. The side of the planet facing its star has temperatures more than 2,000 Kelvin(more than 3,140 Fahrenheit), hot enough to melt metal.

It was initially unknown whether 55 Cancri e was a small gas giant like Neptune or a large rocky terrestrial planet. In 2011, a transit of the planet was confirmed, allowing scientists to calculate its density.

At first it was suspected to be a water planet. As initial observations showed no hydrogen in its Lyman-alpha transit signature, Ehrenreich mused that its volatiles might be carbon dioxide instead of water or hydrogen.

An alternative possibility is that 55 Cancri e is a solid planet made of carbon-rich material rather than the oxygen-rich material that makes up the terrestrial planets in our solar system. In this case, roughly a third of the planet's mass would be carbon, much of which may be in the form of diamond as a result of the temperatures and pressures in the planet's interior. Further observations are necessary to confirm the nature of the planet.