Planet smallest known planet is PSR B1257+12A, one of the first extrasolar planets discovered, which was found in 1992 in orbit around a pulsar. Its mass is roughly half that of the planet Mercury. The smallest known planet orbiting a main-sequence star other than the Sun is Kepler-37b, with a mass (and radius) slightly higher than that of the Moon. Every planet began its existence in an entirely fluid state; in early formation, the denser, heavier materials sank to the centre, leaving the lighter materials near the surface. Each therefore has a differentiated interior consisting of a dense planetary core surrounded
The empire on which the sun never sets the sun encircles.” Mesopotamian texts contemporary to Sargon of Akkad (c. 2334 – 2279 BC) proclaim that this king ruled “all the lands from sunrise to sunset.” In the early 16th century, the phrase, ""el imperio en el que nunca se pone el sol"" ("the empire on which the sun never sets") originated with a remark made by Fray Francisco de Ugalde to Charles I, who as king of Spain and as Holy Roman Emperor by the name of Charles V, had an empire, which included many territories in Europe, islands in the Mediterranean and Atlantic, cities in North Africa