There’s something new in Yellowstone National Park, and it’s hot and corrosive. It’s also, “been sneaking up on the park for the last 20 years,” and has grown to be the size of four soccer fields, said Greg Vaughan, a research scientist with the Yellowstone Volcano Observatory.

That’s not anything to worry about. Carved by ancient volcanic activity and peppered by ever-changing, kaleidoscopic natural beauty, Yellowstone, the world’s oldest national park, is monitored extremely closely by scientists. As it covers a whopping 3,472 square miles of land across three different states, you can’t expect them to spot every single new natural feature the moment it appears.

But with some satellite sleuthing, the emerging warm spot has finally been discovered by Dr. Vaughan and his colleagues, who reported the discovery in a blog post on the Yellowstone Volcano Observatory’s website earlier this month.

This thermal area is the newest addition to a family of many thousands of geothermal features at Yellowstone that are often mercurial and occasionally hyperactive.