55 Cancri e

55 Cancri e, also carrying the official designation 55 Cancri Ae and the proper name Janssen, is an exoplanet orbiting the Sun-like star 55 Cancri A. It has about eight times Earth's mass and roughly twice Earth's diameter, and it was discovered in data gathered between 2003 and 2004, announced in 2004, making it the first super-Earth found orbiting a main-sequence star. It is the innermost known planet in its system, completing an orbit in under 18 hours, a period that later observations in 2010 corrected downward from an earlier estimate of about 2.8 days.