All planets spin on an axis and orbit the sun.
Nine planets are in our solar system as well as the sun and the planet's moons or satellites. All nine planets are completely solid or have a solid core in the center of the planet. Six out of nine planets orbit the sun in the same direction. The planets nearest the sun such as Mercury and Venus receive more heat than those far away from the sun such as Neptune and Pluto. The temperature on the planets are estimated from measurements of infrared radiation or heat waves and what the planets send out which are radio waves .