Scientists are still researching—and debating—how large gaseous planets form.
Ancient civilizations observed Jupiter in the night sky, but humanity still doesn’t completely understand how it and other giant gas planets are born. One theory is that they began as rocky planets that slowly accumulated thick atmospheres and expanded into big gaseous bodies over millions of years. But there might be a faster route. Solar systems grow from protoplanetary disks, a large stew of primordial gases surrounding a massive solar seed called a protostar. Over thousands of years, the protostar’s gravity sucks in material from the disk’s outer reaches. As more gas swirls inward, it’s packed into dense spiral arms. While the protostar will eventually consume the gas closest to it, material farther away may spin off and condense into a Jupiter-like planet. Watch the video to see this process unfold.