This is a diagram of Jupiter, Saturn, Uranus and Neptune. There is also a small image of Earth in the top right-hand corner of the image. The four planets have a cut-out, displaying the centre. The centre of each of them are coloured brown, representing the core (rock, ice). For Jupiter and Saturn, they have a dark grey colour as the next layer, representing metallic hydrogen, and a lighter grey towards the edge of the planet, representing molecular hydrogen. For Uranus and Neptune, there is a different shade of grey next to the core, representing mantle (water, ammonia, methane ices), and another shade of grey towards the edge of the planet, representing hydrogen, helium and methane gas.