The nine planets in order are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and, if it's still considered the ninth planet, Pluto. However, not only has Pluto been demoted to a dwarf planet by some astronomers, but its orbit is so eccentric that there are times when it's closer to the sun than Neptune.Know More
The inner planets are Mercury, Venus, Earth, and Mars. They have rocky surfaces. Mercury, the closest planet to the sun, rotates very slowly on its axis in comparison with Earth. It is very hot on the surface that faces the sun and very cold on the side that is turned away from the sun. Because Venus is covered with clouds, it is subject to a runaway greenhouse gas effect that makes it so hot that spacecraft that land there can only function for a few minutes before being destroyed. Earth, in what scientists call the "Goldilocks zone," is just right for life. Mars isn't as cold as the side of Mercury that faces away from the sun, but its atmosphere is thin and made up mostly of carbon dioxide.
The other planets are much larger than the four inner planets. All of them have rings, though the rings around Saturn are the most prominent.