Which celestial body holds the title of being a planet in our solar system?

Earth is classified as a planet within our solar system due to its specific characteristics that align with the criteria defined by the International Astronomical Union (IAU) for what constitutes a planet. These criteria include orbiting the Sun, having sufficient mass to assume a nearly round shape (hydrostatic equilibrium), and having cleared its orbital path of other debris. Earth meets all these requirements, as it revolves around the Sun and has a stable, spherical shape with its own distinct orbital path.

In contrast, the Moon is classified as a natural satellite, meaning it orbits a planet rather than the Sun directly. Sirius is a star, and while it is part of our galaxy, it does not fulfill the criteria to be classified as a planet. The Sun, being the central star of our solar system, is also not considered a planet; it is categorized as a star, which generates energy through nuclear fusion.