The outer planets, also known as the gas giants, are primarily composed of gases and ices rather than solid rock like the inner planets.

Here's a breakdown of their composition:

* Jupiter and Saturn: These planets are primarily made up of hydrogen and helium, similar to the Sun. However, they also have small amounts of heavier elements like methane, ammonia, and water.

* Uranus and Neptune: These planets are also primarily composed of hydrogen and helium but have a higher proportion of heavier elements than Jupiter and Saturn. They contain a significant amount of ices, such as water, ammonia, and methane, which give them their characteristic blue color.

It's important to note that:

* The outer planets don't have solid surfaces like Earth. They have a thick atmosphere that gradually transitions into a dense, fluid interior.

* The term "ice" refers to compounds that are solid at the extremely cold temperatures found in the outer solar system.

* The exact composition of the outer planets' interiors is still being studied.

Here's a table summarizing the key components:

| Planet | Primary Composition | Other Important Components |

|---|---|---|

| Jupiter | Hydrogen, Helium | Methane, Ammonia, Water |

| Saturn | Hydrogen, Helium | Methane, Ammonia, Water |

| Uranus | Hydrogen, Helium | Water, Ammonia, Methane |

| Neptune | Hydrogen, Helium | Water, Ammonia, Methane |