Whats the largest and densest of the four rocky planets in our solar system?”
The third planet from the Sun, Earth, is the fifth largest with a diameter of 12,756 kilometers (7,928 miles). This rocky object is the densest major planetary body in our Solar System. It also has an unusually large satellite for its size, as Earth’s Moon has about a quarter of its diameter. By mass, the Earth is composed of mostly iron (35 percent), oxygen (30 percent), silicon (15 percent), and magnesium (13 percent). It is made of distinct layers: a thin crust, upper mantle, lower mantle, outer core, and inner core, as well as transition zones. The crust is thinner under the oceans but thicker under the continents. While the inner core and crust are solid, the outer core and mantle layers are semi-fluid. Discovered in the 1930s, the inner core appears to be a solid sphere of mostly iron and nickel. In 2002, its diameter was finally measured to be about 1,520 miles (2,440 km) across. There appears to be an “inner inner” core that may be about 370 miles (600 km) in diameter. Accordin
