Researchers at Stanford recently found evidence of an exoplanet being formed orbiting a star approximately 450 light years away. They were observing gaps in the debris/gas disk of the parent star and found evidence of the planet. The researches the determined this newly forming planet to be similar to Jupiter. They were able to observe the process planets grow from rocky/icy cores into gas giants. As hydrogen heats up, it becomes excited and through spectroscopy can be observed as a H-alpha emission. This new evidence gives insight into how exoplanets are formed.
Source: https://news.stanford.edu/pr/2015/pr-proto-planet-forming-111815.html
