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
Mission: Earth, Voyage to the Home Planet Mission: Earth, Voyage to the Home Planet Mission: Earth, Voyage to the Home Planet is a children's literature book by science writer June A. English and astronaut Thomas David Jones that was published in 1996 by Scholastic. Jones was among the crew members of the Space Shuttle "Endeavour" during an eleven-day mission in space, which was launched in April 1994 to study the ecological well-being of Earth using specialized radar technology. The book, which is illustrated with radar images and picturesque photographs, chronicles the mission and Jones' experiences of it. "Mission: Earth, Voyage to the Home Planet" received a generally