Question

I want to know about what do all planets contain in them

Answer 1

Each planet is a little different on the inside. And what’s inside a planet can shape what’s on the outside.

Rocky planets, like Earth, are wrapped in a thick crust. Beneath Earth’s crust is the mantle. The mantle is quite solid, but it actually behaves more like a fluid. It flows and deforms.

Other rocky planets—Mercury, Mars, and Venus—likely have similar interiors to Earth’s. It appears Mercury has the biggest core, at least compared to its size.

Then there are the giant gas planets: Neptune, Saturn, Jupiter and Uranus
Each of these planets in the outer solar system is surrounded by different gases. We couldn’t stand on them.

Hope this helps :)