Although it does not meet the official definition of a planet as of 2015 and was never widely considered one, some scientists consider the moon a planet. According to NASA, some planetary scientists classify it as a terrestrial planet.
The International Astronomical Union defines a planet as a celestial body that is in orbit around the sun and large enough to form a circular shape and to collect debris in its area. By that definition, the moon is not a planet because its barycenter, which is the point that it orbits, is located within the Earth. However, the moon is gradually moving farther away from the Earth and may eventually become a planet. Some scientists argue that its size and orbit are large and distinct enough that it, along with Earth, should be considered a double planet.