What celestial object orbits Earth, and why is it not classified as a planet?

The Moon is the celestial object that orbits Earth. It is our planet's only natural satellite [1][10][2][19].

Why the Moon is not a planet

The International Astronomical Union (IAU) set a clear definition in 2006: a planet must be in orbit around the Sun [4][12][6]. The Moon, however, circles Earth, not the Sun [8][16][17]. Because it travels around a planet instead of a star, it falls into the satellite (or moon) category [3][9][11]. The IAU even spells out that satellites are not planets [7].

A more technical point: the Earth–Moon system's center of mass (barycenter) lies inside Earth, so the Moon does not qualify as a companion planet in a double‑planet setup either [20]. Simply put, if you're circling a planet, you're a moon—not a planet.