* Atmosphere: Neptune's atmosphere is composed mostly of hydrogen and helium, with trace amounts of methane, ammonia, and water vapor. The planet's blue color is caused by the absorption of red light by methane molecules in the atmosphere.

* Clouds: Neptune has a complex and dynamic cloud system. The planet's most famous cloud feature is the Great Dark Spot, a large, dark storm that was first observed in 1989.

* Storms: Neptune is a very stormy planet. The planet's winds can reach speeds of up to 2,000 miles per hour (3,200 kilometers per hour).

* Magnetic field: Neptune's magnetic field is very strong. The planet's magnetic field is responsible for the planet's aurora borealis and aurora australis.

Uranus

* Atmosphere: Uranus's atmosphere is composed mostly of hydrogen and helium, with trace amounts of methane, ammonia, and water vapor. The planet's blue-green color is caused by the absorption of red light by methane molecules in the atmosphere.

* Clouds: Uranus has a complex and dynamic cloud system. The planet's most famous cloud feature is the White Spot, a large, bright storm that was first observed in 1997.

* Storms: Uranus is a very stormy planet. The planet's winds can reach speeds of up to 500 miles per hour (800 kilometers per hour).

* Magnetic field: Uranus's magnetic field is very weak. The planet's magnetic field is responsible for the planet's aurora borealis and aurora australis.