Illustration of the planet 55 Cancri e, also called Janssen. This is an exoplanet orbiting 55 Cancri A. Its mass is thought to be around 8.6 Earth masses, making it a so-called 'Super-Earth'. The planet orbits its star so closely that it completes an orbit in less than 18 hours. Its proximity to its star - only 0.015 astronomical units, or 1/20th of the Mercury-Sun separation - means that the planet is exceptionally hot and likely volcanic, as this depiction shows. The side of the planet facing the star has an estimated temperature of around 2000 Kelvin, hot enough to melt iron, while the far side is around 400 Kelvin cooler.