- Gravity causes orbits
- Planets in the solar system orbit the sun
- Therefore, gravity causes the planets in the solar system to orbit the sun

- Mars is a kind of planet
- Mars is located in the solar system
- Therefore, mars is a planet in the solar system

- Gravity causes the planets in the solar system to orbit the sun
- Mars is a planet in the solar system
- Therefore, gravity causes mars to orbit around the sun

Therefore, gravity causes mars to orbit around the sun
What keeps Mars in orbit around the Sun?
- Gravity causes orbits 
- Mars is a kind of planet 
- Planets in the solar system orbit the sun 
- Mars is located in the solar system