Iâve come up with fewer reasons for giving a child a cell phone earlier, but at least two of them are enough to offset a multitude of others. Keeping tabs on them. As each year passes in a childâs life they venture farther from home and for longer periods of time.
Like the inner planets, the outer planets have similar characteristics to one another. The outer planets are so much larger than the inner planets that they make up 99 percent of the mass of the celestial bodies that orbit the Sun. Although mainly composed of gas, the outer planets also have other ingredients.
The core of the Earth is the center. The inner core is solid, and is 90% iron. But the outer core is a liquid... and it's a good thing it is! More on that later. The outer core is made of a mixture of iron and nickel, with smaller amounts of silicon and oxygen. The outer core officially begins at a depth of 2550 km below the surface of the Earth, down to a final depth of 4750 km at the boundary between the inner and outer core.