flashcards to help you learn the difference between planets and diffrent parts of our universe about 99% Mercury, Venus, Earth, and Mars Jupiter, Saturn, Uranus, and Neptune area just beyond the orbit of Pluto composed of comets orbiting the sun. an area of drifting ice bodies just beyond the outer fringes of the Solar System. Sun and planets from a cloud of gas and dust called nebula. Gravity exceeded the gas pressure and slowely caused the cloud to collapse. As the cloud shrunk gravity increased causing the shape to become spherical. Mainly hydrogen and helium 15,000,000 degrees celcius the unequal spinning of varius layers. they all have atmospheres, terrestrial planets with rocky mineral containing crust. closest planet to the sun, and fastest orbit. closely resembles earth. hottest planet in the solar system, and spins clockwise.