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
Stowaway to the Mushroom Planet Stowaway to the Mushroom Planet " Stowaway to the Mushroom Planet "is the second in the series of "Mushroom Planet" books by Eleanor Cameron, and was published in 1956, two years after "The Wonderful Flight to the Mushroom Planet". This children's book is set in a beach community in California, as well as on a tiny, habitable moon, "Basidium", in an invisible orbit 50,000 miles from Earth. The "Mushroom Planet," visited by the protagonists David and Chuck, is covered in various types of mushrooms and is populated by little green people. The story opens with Theo Bass, the cousin of