- Planets orbit stars
- Gravity causes orbits
- Hence, gravity causes planets to orbit stars

- Gravity causes planets to orbit stars
- The sun is a kind of star
- Planets in the solar system orbit the sun
- Therefore, gravity causes the planets in solar system to orbit the sun

- Gravity causes the planets in solar system to orbit the sun
- Isaac newton discovered the theory of gravity
- So, isaac newton discovered that gravity causes the planets in the solar system to orbit the sun

So, isaac newton discovered that gravity causes the planets in the solar system to orbit the sun
Question: When Isaac Newton theorized that gravity caused objects to fall to the ground, he had also discovered the force that causes
Context: - The sun is a kind of star 
- Planets in the solar system orbit the sun 
- Planets orbit stars 
- Isaac newton discovered the theory of gravity 
- Gravity causes orbits