Abundance of the chemical elements in the Sun and outer planets is similar to that in the universe. Due to solar heating, the elements of Earth and the inner rocky planets of the Solar System have undergone an additional depletion of volatile hydrogen, helium, neon, nitrogen, and carbon (which volatilizes as methane). The crust, mantle, and core of the Earth show evidence of chemical segregation plus some sequestration by density. Lighter silicates of aluminum are found in the crust, with more magnesium silicate in the mantle, while metallic iron and nickel compose the core. The abundance of elements in specialized environments, such as atmospheres, or
Return to the Centre of the Earth idea soon after, partly due to Richard Branson's world record attempts to circumnavigate the Earth by hot air balloon and thinking people will relate his music to the event. Soon after, Wakeman came across a newspaper article by Steven Spielberg, "who was talking about have sequels for making films, how you have a story and you spin up from the story for a whole new story, but you have a relationship, which is very comfortable for the people who listen a whole new story, new characters, but there's still a relationship." This prompted the thought in Wakeman's mind, after revisiting