The Vera C. Rubin Observatory announced on 27 October 2026 that it had found a distant object called 2026 ED138. It orbits the Sun beyond Pluto and could qualify as a dwarf planet. For now, it is a candidate: astronomers have traced its path, but have not confirmed its size or shape.
The discovery shows how repeated observations can bring a faint object into view, even in a crowded part of the sky. It also shows the difference between finding an object and knowing exactly what kind of world it is.
Cover image: An annotated composite of Rubin Observatory observations traces 2026 ED138 across the sky. The object is a dwarf planet candidate. Credit: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA. Image processing: M. Jurić (UW), D. de Martin and M. Zamani (NSF NOIRLab). Licensed under CC BY 4.0.
A discovery assembled from years of observations
Rubin team member Matthew Holman identified 2026 ED138 on 13 October while searching through images taken earlier in 2026. Rubin had recorded it 30 times across 20 nights between 4 March and 11 July. Researchers then found it in older images from the Dark Energy Camera, reaching back to 2016. Together, those observations let them trace more than a decade of its orbit.
The object appeared against a dense field of Milky Way stars, where its slow movement was hard to pick out. Comparing images taken on different nights helped the team distinguish it from the background stars.
Why it is still a candidate
2026 ED138 is currently about 46 astronomical units from the Sun. One astronomical unit is roughly the average distance between Earth and the Sun.
The team estimates that the object is between 600 and 1,500 kilometres across. That is a wide range because the estimate depends partly on how much sunlight its surface reflects. A brighter surface can make a smaller object look like a larger, darker one.
To count as a dwarf planet, an object must be massive enough for its own gravity to pull it into a nearly round shape. Rubin’s team says infrared observations are needed to narrow the size estimate and establish whether 2026 ED138 meets that test.
What happens next
Further observations can sharpen the picture of this object. Its orbit is already useful: distant bodies preserve clues about how the Solar System developed and how the giant planets affected smaller objects.
For readers, the key distinction remains simple. Rubin has identified and tracked 2026 ED138. Whether it is a dwarf planet is still an open question.
