Question: Is planet Neptune bigger than Earth?

Reka Nagy answered on 8 Nov 2016:

Much bigger – 3.9 times bigger in fact. What it’s made of is also very different to what Earth is made of:
Its atmosphere is mostly made out of gases such as hydrogen, helium and methane (compared to the atmosphere of Earth which is made mostly of nitrogen, oxygen and argon).
Its surface is very cold, consisting of ice made of water, ammonia and methane. Finally, its core is made of rock and ice – whereas the core of Earth is made of a lot of molten rock that has not yet cooled since Earth was formed.