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.
Thus, the planetesimals that formed in the outer solar system are composed primarily of hydrogen compounds with traces of rock and metal. Hydrogen and helium do not condense in the solar nebula, and are rather abundant in the large orbits of objects in the outer solar system.