Matthew Holman used custom code on Rubin Observatory’s autonomous observational data earlier this month and flagged a bright, very distant object that astronomers are now calling 2026 ED138. The object sits beyond Neptune and is being discussed as a possible dwarf planet.
It is about 4.3 billion miles from the sun, or 46 times farther away than Earth. If later observations show that it is large enough and round enough, it would join Pluto, Ceres, Eris, Haumea and Makemake on the International Astronomical Union’s short list of recognized dwarf planets.
Spokane, Washington announcement
The finding was announced earlier this week at a meeting of the American Astronomical Society’s division for planetary sciences in Spokane, Washington. Paul Byrne, a planetary scientist at Washington University in St. Louis, said, "This is incredibly exciting." He added, "It heralds a new era of solar system and planetary science."
Samantha Lawler, an astronomer at the University of Regina, said, "I love it. It makes me very happy." She added, "It’s nice to have confirmation that the giant, expensive, complicated machine is working."
Matthew Holman and Rubin
Holman, an astrophysicist at the Center for Astrophysics, said Rubin’s autonomous data let him identify the object by running his own code through the survey output. The object’s brightness and distance put it in the Kuiper Belt, the region beyond Neptune where Pluto, Haumea and Makemake are found.
Byrne said, "This part of the solar system is largely unknown, and every detection such as this brings up a step closer to understanding how ours and planetary systems as a whole came to be." The object is still being treated as possible, not final.
Kuiper Belt observations
The next step is more observing. Future telescope work has to settle whether 2026 ED138 is large enough and round enough to qualify as a dwarf planet, which is the line that separates a small body from one that can join the recognized list.
Rubin is expected to discover an estimated 32,000 objects beyond Neptune’s orbit over the next decade, and 2026 ED138 is one of the first signs of how many distant bodies the survey may uncover.
