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
Third from the Sun called "Earth". Todd VanDerWerff of "The A.V. Club" rated it A and called the twist "justifiably famous". The episode contains an anomaly: the planet revealed as being Earth is described as being in another solar system, "11 million miles" away. The next closest solar system to our sun is actually 25.7 trillion miles away. Third from the Sun "Third from the Sun" is episode 14 of the American television anthology series "The Twilight Zone". It is based on a short story of the same name by Richard Matheson which first appeared in the first issue of the magazine "Galaxy Science