| Abstract: | Most of the discovered exoplanets in our galaxy are close-in planets in the mass range of 1-20 Earth masses. The interior structure of these planets is poorly understood, and is usually modelled as a 4-layer object (iron, rock, water, gas), similar to the structure of the Earth. However, as these planets are formed in different conditions than our own Earth, this structure should be reexamined. We find that planetary interiors in the mass range of 1-20 Earth masses may be significantly different from the simplified layered structure. Our findings are based on planet formation and evolution models, and on knowledge from laboratory experiments of material interaction. I will show some of these new findings and discuss how we expect the interiors of these planets to look like. |