An ice planet is like a big snowball that freezes all the time! Imagine going outside on a very cold winter day and feeling your fingers and toes freeze. That is what it's like all the time on an ice planet. Instead of being made of rocks and gases like Earth, an ice planet is made mostly of frozen water and other icy materials.
These planets are usually really far from their star or sun, so they don't receive much warmth or light. That's why they stay so cold and icy. The temperature is so low that you would freeze instantly without any protection. The ice on the planet is a kind of solid form of water, and the air is also really cold and thin. Everything on this planet is frozen, even the air!
If you tried to visit an ice planet, you would have to wear a special suit that keeps you warm and gives you air to breathe. You would also need special boots that help you walk on the icy surface without slipping. Ice planets are fascinating to scientists because they can teach us a lot about our own solar system and how planets form.