Himmelskörper: Möglicher weiterer Zwergplanet im Sonnensystem

Astronomers have discovered a potential new dwarf planet in our solar system, according to the Vera C. Rubin Observatory. The object, designated 2026 ED138, could belong to the largest and brightest objects beyond Pluto's orbit, according to initial analyses. The object was found by Matthew Holman from the Harvard-Smithsonian Center for Astrophysics in Cambridge, who analyzed data collected by the observatory this year.

Using a self-developed search code, Holman combed through billions of moving object detections, and immediately noticed ED138's unusual brightness and distance, indicating an extraordinary size. After double-checking the data, Holman said, "My first reaction was joyful disbelief. Such objects are very rare, so I immediately checked if I or the code had made a mistake."

The team then sought additional recordings, including from archive images, to trace ED138's orbit over more than a decade. Currently, ED138 is located about 46 Astronomical Units from the Sun, with Pluto averaging 40 Astronomical Units. To be classified as a dwarf planet, an object's size and shape are crucial factors. Based on brightness, distance, and estimated surface reflectivity, the team estimates ED138's diameter to be between 600 and 1,500 kilometers.

Since icy bodies of this size are typically round, it meets the criteria to be classified as a dwarf planet. A key difference between a planet and a dwarf planet is that a planet has cleared its orbit of smaller bodies. Last confirmed in 2008, ED138's orbit is relatively well-known, according to planetary researcher Ralf Jaumann from the Free University of Berlin.

"The size can only be estimated, so between 600 and 1,500 kilometers is quite imprecise." If ED138 is indeed as large as 1,500 kilometers, it has a good chance of being recognized as a dwarf planet. Regardless, ED138 is a promising candidate, as there are many others. "It's interesting that with a telescope in Chile, we can find such an object out there and track it, and we've mapped such a large part of its orbit," Jaumann noted.

So far, there are five dwarf planets officially recognized by the International Astronomical Union (IAU): Pluto, Ceres, Eris, Haumea, and Makemake. Last recognized in 2008, there are also numerous dwarf planet candidates. The Astronomical Union introduced the new class of celestial bodies 20 years ago, following Pluto's demotion from planet to dwarf planet.