Geology of solar terrestrial planets Earth, and Mars) have substantial atmospheres; all have impact craters and tectonic surface features such as rift valleys and volcanoes. The term "inner planet" should not be confused with "inferior planet", which refers to any planet that is closer to the Sun than the observer's planet is, but usually refers to Mercury and Venus. The Solar System is believed to have formed according to the nebular hypothesis, first proposed in 1755 by Immanuel Kant and independently formulated by Pierre-Simon Laplace. This theory holds that 4.6 billion years ago the Solar System formed from the gravitational collapse of a giant molecular
Planet Stories is the folk-tale, the hero-tale of our particular niche in history". Also arguing in support of "Planet Stories", science fiction critic John Clute has commented that "the content was far more sophisticated than the covers". Bradbury's work for "Planet Stories" included two of the stories that he later incorporated into "The Martian Chronicles", including "The Million Year Picnic"; only one other story in the series had appeared before this. He also collaborated on a story with Brackett, "Lorelei of the Red Mist", based on an idea of hers, which appeared in the Summer of 1946. His stories for "Planet" demonstrate