According to NASA, astronomers have discovered at least 146 moons orbiting planets in Earth's solar system. As of 2014, 27 more moons await official confirmation of their discovery. This total does not include the six moons of the dwarf planets or tiny satellites that orbit asteroids and other celestial objects.
Moons are also known as satellites. Out of all the terrestrial planets, which are rocky planets in Earth's inner solar system, Mercury and Venus are the only planets that do not have any moons. Earth has one moon and Mars has two small moons. In the outer solar system, Jupiter and Saturn, which are known as gas giants, have numerous moons. Also, Uranus and Neptune, which are known as ice giants, have numerous moons.