Astronomers using NASA’s Hubble Space Telescope and the Keck Observatory in Hawaii have found what may be a rare three-body system in the Kuiper Belt, a distant region of icy objects beyond Neptune.
If confirmed, this would be only the second known trio of Kuiper Belt Objects (KBOs), suggesting there may be more waiting to be discovered.
The discovery centers around Altjira, a system located 3.7 billion miles from Earth. Hubble images originally showed two objects orbiting each other.
However, after analyzing 17 years of data, researchers now believe that one of those objects is actually two separate bodies, forming a triple system.
The finding supports a theory that some Kuiper Belt objects may have formed in groups of three, not from collisions but from gravitational collapse—a process where material from the early solar system came together due to gravity, similar to how stars often form in pairs or triples.
“This tells us that the Kuiper Belt might not be so different from other parts of space, like star systems,” said lead researcher Maia Nelsen from Brigham Young University.
What Is the Kuiper Belt?
The Kuiper Belt is a vast region beyond Neptune filled with icy remnants from the early solar system.
Over 3,000 KBOs have been discovered so far, with scientists estimating hundreds of thousands more exist. The largest KBO is the dwarf planet Pluto, which NASA’s New Horizons mission visited in 2015.
A closer look at Altjira
Altjira is part of the cold classical KBOs, a group that formed in the same place they exist today.
The system appears to have three members: an outer object orbiting two inner objects that are so close together they are difficult to distinguish.
Scientists detected this by observing how the outer object’s orbit slowly changed over time, a clue that the inner object was more complex than it appeared.
“A triple system was the best explanation when we tested different models with Hubble’s data,” said co-author Darin Ragozzine. “It could also be a contact binary, where two objects are touching, or even something oddly flat, like a pancake.”
What’s next for Altjira?
Although there are no missions planned to visit Altjira, astronomers have a unique opportunity to study it. The system has entered an eclipsing season, where its objects pass in front of each other. This will last for the next 10 years, allowing scientists to learn more about its size, shape, and orbit.
NASA’s James Webb Space Telescope will also observe Altjira in its upcoming studies, helping confirm whether its components appear the same under different types of light.
This discovery adds to our understanding of how objects in the Kuiper Belt formed and hints that more three-body systems may be hidden in the distant reaches of our solar system.
Source: NASA.
