A giant doughnut encircles the realm of the planets. Known as the Kuiper Belt, it probably consists of billions of chunks of ice and rock. And one of its first known members was discovered 25 years ago today.

Dave Jewitt and Jane Luu found the object while scanning the sky from Mauna Kea in Hawaii. It was designated 1992 QB1. It took a while longer to confirm its orbit, which placed it well beyond the planets.

Astronomers had suspected that there were objects out there for decades — debris left over from the birth of the solar system. But that region is so far away, and most of its inhabitants are so small, that it took a long time to find any of them.

The discovery of 1992 QB1 confirmed the existence of the Kuiper Belt. And since then, astronomers have found more than a thousand other members. The belt extends billions of miles beyond Neptune, the outermost major planet. And it’s quite thick, with its members following orbits that carry them well above and below the plane of the solar system. So the Kuiper Belt probably should be known as the Kuiper Doughnut.

QB1 wasn’t the first member of the Kuiper Belt to be discovered. That honor goes to Pluto, which was found in 1930. At the time, though, no one had suggested that there were more objects beyond Neptune. That’s one reason why Pluto was designated as a planet. It wasn’t until later that astronomers realized that Pluto is a member of something much bigger: the Kuiper Belt.

Script by Damond Benningfield