Here are four planets in our solar system that are primarily made of gas:

1. Jupiter: The largest planet in our solar system, Jupiter is a gas giant composed mainly of hydrogen and helium.

2. Saturn: Known for its stunning ring system, Saturn is another gas giant with a similar composition to Jupiter.

3. Uranus: A much colder gas giant than Jupiter and Saturn, Uranus has a unique tilt and is mostly composed of hydrogen, helium, and methane.

4. Neptune: The outermost planet in our solar system, Neptune is also a gas giant with a similar composition to Uranus.