What Is the Kuiper Belt?

donut-shaped ring of celestial bodies explored

By Jonny Lupsha, Wondrium Staff Writer

The asteroid belt isn’t the only ring of celestial bodies orbiting our solar system. A much wider ring starting near Neptune contains countless icy formations. Discover the Kuiper Belt for yourself today.

Kuiper Belt
The Kuiper Belt is a ring of icy celestial objects in the outer reaches of our solar system where dwarf planets are located. Photo by NASA / NASA.gov /Public Domain

The dwarf planet Pluto has had an interesting half-century. Originally considered the ninth planet in our solar system, it was demoted in the 2000s following the discovery of a dwarf planet of equal size but three times the distance from the Sun. The dwarf planet, Eris, threw the scientific community into a debate that changed our definition of planets, taking Pluto down in the process.

Eris is in the thick of the Kuiper Belt, which is a ring of icy celestial objects in the outer reaches of our solar system. It’s been in the news lately, as one of its dwarf planets, Quaoar, was recently found to have its own rings around it, like Saturn.

So, what’s the story with the Kuiper Belt? In her video series Great Heroes and Discoveries of Astronomy, Dr. Emily Levesque, Associate Professor in the Department of Astronomy at the University of Washington, takes viewers beyond Neptune to explore the Kuiper Belt and its wonders.

What Is the Kuiper Belt?

In the 1940s, an astronomer named Gerard Kuiper studied Pluto and Saturn’s moon Titan. Shortly afterward, he wrote a paper in which he postulated that Pluto may be part of a ring of small bodies orbiting the Sun starting around Pluto. He ended up being more right than he knew.

“The Kuiper Belt is a wide ring of small rock-and-ice objects orbiting our Sun,” Dr. Levesque said. “The ring begins just past Neptune and stretches to more than 90 billion miles away from the Sun. The belt may be named for Kuiper, but he wasn’t the researcher who predicted it. That distinction goes to Julio Angel Fernandez Alves, a Uruguayan astronomer.”

In 1980, Fernandez published a paper detailing the orbits of comets, suggesting they must be coming from somewhere nearby, perhaps a belt of comets and other rocky and icy objects. His idea caught on, and research on this theoretical belt began in the early 1990s. David Jewitt and Jane Luu, two astronomers, discovered the 70-mile-wide object Albion in August 1992, marking the first object in the Kuiper Belt to be found.

Why Is Pluto No Longer Considered a Planet?

“After Jewitt and Luu’s discovery, the study of Kuiper Belt objects exploded—today, we estimate that there are at least 35,000 objects as big as Albion—or even bigger—in the belt,” Dr. Levesque said. “In the following years, some of these became highly automated, with robotic telescopes automatically capturing repeat images of the sky and software that could simulate ‘blinking images’ and pass along anything that looked enough like a moving object to a human expert.”

“Blinking images” are a very simple process in which an astronomer sequences several images to make a movie, not dissimilar to a flipbook. This same method of astronomical study was used by Jewitt and Luu to discover Albion.

“Astronomer Mike Brown was examining one data set like this in 2005 when he came across a surprisingly bright and slow-moving object,” Dr. Levesque said. “He recognized that his survey had found a new Kuiper Belt object, and that it was enormous. The object, later dubbed Eris, was the largest Kuiper Belt object ever found at the time—at least, officially.”

Brown’s discovery of Eris led to the controversy surrounding dwarf planets and, subsequently, Pluto’s demotion.

Great Heroes and Discoveries of Astronomy is now available to stream on Wondrium.

Edited by Angela Shoemaker, Wondrium Daily