The Earth
Earth is the third planet from the Sun. It is also the largest of the Solar System's four terrestrial planets.
The Earth is divided into several layers which have distinct chemical and seismic properties.
The crust varies considerably in thickness, it is thinner under the oceans, thicker under the continents. Most of the mass of the Earth is in the mantle, and the majority of the rest in the core. The core is probably composed mostly of iron (or nickel/iron)
Unlike the other terrestrial planets, Earth's crust is divided into some separate solid plates which float around independently on top of the hot mantle below.
The Earth is divided into several layers which have distinct chemical and seismic properties.
The crust varies considerably in thickness, it is thinner under the oceans, thicker under the continents. Most of the mass of the Earth is in the mantle, and the majority of the rest in the core. The core is probably composed mostly of iron (or nickel/iron)
Unlike the other terrestrial planets, Earth's crust is divided into some separate solid plates which float around independently on top of the hot mantle below.
A very important fact is that 71% of the Earth's surface is covered with water. Earth is the only planet on which water can exist in liquid form on the surface, and, of course, liquid water is essential for life as we know it. The heat capacity of the oceans is also very important in keeping the Earth's temperature relatively stable. The Earth's atmosphere is 77% nitrogen and 21% oxygen.