First Moon Outside Our Solar System Detected by VLT

For six decades, astronomers have mapped thousands of worlds circling distant suns — but moons have stayed frustratingly out of reach. That changed in July 2026, when a team using the European Southern Observatory's Very Large Telescope (VLT) in Chile found compelling evidence for the first confirmed moon-like object ever detected outside our Solar System.

The discovery centers on a peculiar three-body system: a star called CD-35 2722, a brown dwarf that orbits it, and a third object — roughly the size of Jupiter — that orbits the brown dwarf. It's that third body, now called an exosatellite, that astronomers believe represents the first plausible detection of an exomoon.

"This system is truly unique and represents a breakthrough: the first plausible detection of an exosatellite," said Alice Zurlo, Director of the YEMS research center at the Universidad Diego Portales in Chile and co-author of the study published in Nature.

Lead author Kevin Hoy, an ESO student also affiliated with Universidad Diego Portales, described the system as "super weird." In our Solar System, moons orbit planets, which orbit stars — a neat two-tier hierarchy. The CD-35 2722 system adds a third tier, with a Jupiter-sized body orbiting a brown dwarf, which in turn orbits a star.

"This system is somewhat hard to define using Solar-System-based words like 'planet' and 'moon,'" Hoy said. "The exosatellite is clearly massive enough to be a planet, but it does not orbit a star, though it orbits an object that orbits a star. Being the third wheel in this system makes us want to call it a moon, even if it's nothing like the small, rocky moons we have in our system."

The team used the CRIRES+ spectrograph on the VLT, applying the radial velocity method — the same technique that first confirmed a planet around a Sun-like star in 1995. By detecting subtle wobbles in the brown dwarf's motion caused by the gravitational pull of the orbiting body, they built a compelling case for the exosatellite's existence.

Why This Matters

Over 6,000 exoplanets have been confirmed since the early 1990s, but exomoons have remained stubbornly elusive. Only a handful of candidates had been spotted before, with limited supporting evidence. The CD-35 2722 detection is the most persuasive yet.

Six of the eight planets in our Solar System have natural moons, suggesting these bodies should be common throughout the universe. The difficulty was always in detecting them — moons are much smaller and dimmer than planets, making them extraordinarily hard to spot across interstellar distances.

If this detection holds, it could trigger a wave of exomoon discoveries similar to the explosion of exoplanet detections that followed the first confirmed detection in 1992. Aleksander Wolszczan, who made that historic first detection and who is now 80, had predicted that thousands more planets would follow — and he was proved spectacularly right.

"We have a clear delineation between the planets and the Sun in the Solar System, so defining things like moons is simple," Zurlo noted. "In the CD-35 2722 system, where we are blurring the lines between stars, planets, and moons, the whole thing becomes more complicated to describe."

The study was carried out under YEMS, a multidisciplinary research center dedicated to the detection of exoplanets and exomoons, and published in Nature in July 2026. Astronomers worldwide are expected to train their instruments on the system to verify the finding in the months ahead.