Why was Ceres, discovered in 1801, eventually reclassified away from being a planet?

Answer

More similar, smaller bodies were found nearby in the asteroid belt

The case of Ceres, discovered in 1801, perfectly illustrated the inherent difficulties in classifying solar system objects without firm, explicit rules. Initially, Ceres was accepted as a planet because it met the general criteria of orbiting the Sun and being substantial. However, subsequent discoveries in the region where Ceres resides revealed a multitude of other similarly sized, smaller objects. This discovery shifted the perception from Ceres being a unique, singular major body to being one member of a larger population, now known as the asteroid belt. Consequently, Ceres was reclassified as an asteroid. This transition showed that the definition was susceptible to historical context and the discovery of related objects; what was once considered a lone planet could become part of a new, distinct class of smaller bodies.

Why was Ceres, discovered in 1801, eventually reclassified away from being a planet?

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