Of the eight planets in the Solar System, the Earth is one of the inner planets and is made of rock and metal. You may also hear it described as a terrestrial planet as opposed to gas giants that include Jupiter and Saturn. Because of our distance from the Sun and our atmosphere, we exist in a very narrow temperature range that allows water to exist in solid, liquid, and gas states across the planet. We live in the "Goldilock's Zone" or for those of you who will become scientists… the circumstellar habitable zone.