Nysa Imaged as Three-Lobed Asteroid With a Tiny Moon
SHARK-VIS on the Large Binocular Telescope shows main-belt asteroid Nysa as three lobes joined by narrow necks. The same campaign turned up a moon about a kilometer across.
Asteroid Nysa, one of the brightest bodies in the main belt between Mars and Jupiter, has been imaged as three lobes strung together by narrow necks. The pictures were taken on February 15, 2026 UTC by the SHARK-VIS instrument on the Large Binocular Telescope atop Mount Graham in Arizona, and released on the evening of July 29 by Lowell Observatory in Flagstaff. The same campaign turned up a moon a little over one kilometer wide.
Catalogued as asteroid 44, Nysa measures roughly 75 kilometers across. It is the largest and brightest of the E-type asteroids, whose enstatite-rich surfaces are tied to the inner regions of the early solar system. Light curves and earlier observations had it pegged as elongated, and in some models as a two-lobed body. Three separate lobes is not something any of those models called for.
“The images reveal a remarkably unusual object. The most likely explanation is that Nysa is either a contact trinary, consisting of three connected components, or an extremely irregular coherent body unlike anything we’ve previously observed,” said Kate Minker, an astronomer at Lowell Observatory and lead author of the study, in the observatory’s statement.
The two readings cannot yet be separated. A contact trinary would be three distinct chunks that drifted together slowly and stayed stuck.
How the images were made
The work rests on two observing runs with two separate systems. The first is SHARK-VIS on the Large Binocular Telescope, the second is SPHERE/ZIMPOL on the European Southern Observatory’s Very Large Telescope in Chile. A further campaign on March 21, 2026 is what confirmed that a natural satellite circles the asteroid.
The moon carries the provisional designation S/2026 (44) 1. It is slightly more than a kilometer across and sits at least 170 kilometers out. Pulling something that faint out of the glare of a body seventy times wider meant borrowing a method normally used to hunt for planets around other stars.
“Our technique is a bit like figuring out Christmas presents while they’re wrapped,” said Al Conrad of the Large Binocular Telescope Observatory.
Why the shape of Nysa matters
Two lobes joined at a neck is a familiar arrangement, but nearly every known case was seen up close, during a spacecraft flyby:
- Itokawa, photographed by Japan’s Hayabusa probe in 2005
- Arrokoth in the Kuiper Belt, captured as New Horizons passed on January 1, 2019
- Selam, the moon of asteroid Dinkinesh, imaged by the Lucy spacecraft on November 1, 2023 and itself made of two fused pieces
None of them has three lobes. If the shape reconstruction for Nysa holds up, it would be the first case of its kind, on a body no mission has ever visited.
“These observations likely represent the closest competition to spacecraft-quality imaging ever achieved from the ground,” Kate Minker said in the Lowell Observatory statement.
What the images do not prove
The paper is titled Unmasking (44) Nysa: Evidence for a Trilobate Structure, and the preprint is posted as arXiv 2607.25786. Preprint means the text has not yet cleared peer review and the conclusions can still shift. 19 researchers from 10 institutions are on it, among them Lowell Observatory, the European Southern Observatory, Italy’s INAF, Charles University in Prague, the Large Binocular Telescope Observatory, Université Côte d’Azur and France’s CNRS.
The limits are stated plainly. The shape comes out of image processing rather than close-range measurement, so whether the lobes are truly three separate bodies stays open. The 170 kilometers is a floor, not a mapped orbit, which would take more passes to pin down. The authors do not claim Nysa was assembled by collision, or that the lobes were once three asteroids, only that the observations point that way.
