The definition of a finger is a digit on your hand or anything that looks like or functions like a finger. Thumb - The thumb is the short, stubby finger that can rotate in all directions (opposable thumb). The anatomical name for the thumb is the 1st finger.
Pluto is thought to be made of mostly ice. It probably also has a small rocky core which might contain some metals. The ice on the surface of Pluto is made of frozen nitrogen, methane and carbon monoxide. The ice covering Pluto reflects a lot of sunlight making it appear brighter than it would if it had been covered with a darker rocky material. 1  Javascript must be enabled to use Cool Cosmos.
Earth and the other three inner planets of our solar system (Mercury, Venus and Mars) are made of rock, containing common minerals like feldspars and metals like magnesium and aluminum. So is Pluto. The other planets are not solid. Jupiter, for instance, is made up mostly of trapped helium, hydrogen, and water. In our solar system, the four gas giants are Jupiter, Saturn, Neptune, and Uranus. Planets with their relative sizes to scale. The tiny bluish dot at the lower left is Earth. The tiny red dots to either side are Venus and Mars.