It wasn't till Huygens had two things: He had a good theory of planetary rings and how the solar system operated, and he had better telescopic, more fine-grain data in which he could figure out that as the Earth is going around faster -- according to Kepler's Laws -- than Saturn, then we catch up with it.
Heigensam bija divas lietas. Viņam bija laba teorija par planētu gredzeniem  un to, kā darbojas saules sistēma. Turklāt viņam bija labāki un precīzāki teleskopiskie dati, kuros Heigenss varēja noteikt,  ka Zeme, saskaņā ar Keplera likumiem, riņķo ātrāk, nekā Saturns,  ka mēs to apdzenam.