Some of the strangest weather in the solar system doesn’t happen on Earth, or even Jupiter’s Great Red Spot - it happens in the interior of the Ice Giants like Neptune and Uranus. Specifically, scientists have long believed that, at certain pressure and temperatures, it literally rains diamonds inside of these planets. And for the first time, scientists have mimicked the process they believe creates that. A new paper by physicists at the Lawrence Livermore National Laboratory (LLNL), published in Nature Physics, resolves a 20 year old scientific mystery, and shows how the same physics that makes it rain diamonds inside Neptune could also help us triple our fusion energy output.