The broadest classification of life splits all organisms into three groups called domains. The three domains of life are bacteria, archaea and eukaryota.

Mantle makes up 84% of the Earth's volume and has an average thickness of approximately 1,800 miles (2,900 km). It is dense, hot, and primarily solid although in places it behaves more like a viscous fluid as the plates of the upper mantle and crust gradually "float" along its circumference.

In contrast to the solid terrestrial planets, the outer planets (Jupiter, Saturn, Uranus, and Neptune) consist of hydrogen and helium gas and water.

The respiratory system manages respiration which is the process by which blood cells absorb oxygen and eliminate carbon dioxide.

Newton's third law of motion states that For every action, there is an equal and opposite reaction. When an object exerts a force on another object, the second object exerts a force of equal magnitude in the opposite direction on the first object.