Do you love learning about space? Do you know how important the solar system is? This is the audio book for you. All your questions will be answered. Uranus is an ice planet. Most of its mass is a hot, dense fluid of icy materials such as water, methane and ammonia its above a small rocky core. Neptune is more than 30 times as far from the Sun as Earth, Neptune is the only planet in our solar system not visible to the normal human eye.