This is an excerpt from my post on Planet Hunters:
In the 10th paper(!) from the Planet Hunters citizen science program, a stupendously great number, we independently discovered 10 new planet candidates in the K2 *Kepler* data (Campaigns 1 and 3). However, simply discovering them was not the main goal of the new paper. We wanted to explore their neighborhoods.
The environment in which a star is created has a large and enduring impact on how planets form. Under standard planet formation theory, when a star collapses, it forms a disk, called a protoplanetary disk, due to the conservation of angular momentum. It is in this disk of material orbiting the infant star that planets are formed. Solid material clumps together and forms planets. In the inner disk, the material is hotter, so the only solid material is metallic or rocky. In the outer disk, the material is cooler, which allows molecules like ice and frozen ammonia to clump together as well. This extra solid mass in the outer solar system allows the outer planet to grow bigger and eventually capture gas. Interactions between all these planets can then jumble them around.Read More