- Gravity causes orbits
- The earth revolves around the sun
- Hence, gravity causes the earth to revolve around the sun

- Gravity causes orbits
- The moon orbits the earth
- Therefore, gravity causes the moon to orbit the earth

- Gravity causes the earth to revolve around the sun
- Gravity causes the moon to orbit the earth
- Therefore, gravity causes both the orbit of the earth around the sun and the orbit of the moon around the earth

Hence, gravity causes both the orbit of the earth around the sun and the orbit of the moon around the earth
Which characteristic is shared by Earth and the Moon?
- Gravity causes orbits 
- The earth revolves around the sun 
- The moon orbits the earth