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
Geographical centre of Earth system as , in modern Turkey, 1,000 km north of Giza. In 2003, a similar result was yielded by Holger Isenberg: 40°52'0"N, 34°34'0"E. In 2016, Google Maps marked 40°52′N 34°34′E as the geographic centre of the world. In 2007, Susan Wise Bauer claimed in her book " Earliest Accounts to the Fall of Rome", that the theory that the Great Pyramid was the geographical centre of Earth would only hold true if a Mercator projection is used as the map for Earth, which was "unlikely to have been a common practice of the ancient Egyptians". Geographical centre of Earth The