
Given the following passage

"Newton came to realize that the effects of gravity might be observed in different ways at larger distances. In particular, Newton determined that the acceleration of the Moon around the Earth could be ascribed to the same force of gravity if the acceleration due to gravity decreased as an inverse square law. Further, Newton realized that the acceleration due to gravity is proportional to the mass of the attracting body. Combining these ideas gives a formula that relates the mass () and the radius () of the Earth to the gravitational acceleration:",

answer the following question. Note that the answer is present within the text.

Question: The interaction between which two celestial bodies led Newton to produce new insights on the effects of gravity? 

the Moon around the Earth
