human
Why do the Halley’s Comets have such a long orbital period?
assistant
Halley’s Comet has an orbital period of 76 years. The reason for this is that the comet is not a single object, but a collection of many small pieces of ice and rock that orbit the Sun in a similar way to the planets. These pieces of ice and rock are called “nuclei”, and they orbit the Sun in a similar way to the planets, but their orbital periods are much shorter.