First Confirmed Exomoon Discovered Orbiting a Distant Gas Giant

Astronomers have found the first confirmed exomoon—a moon outside our solar system—circling a distant gas planet. The discovery comes as NASA marks the confirmation of 6,000 exoplanets, with thousands more still under review. This new detection adds another milestone in the study of distant worlds beyond our own. The exomoon orbits HD 206893 b, a massive gas planet first discovered in 2021. This planet is 1.25 times wider than Jupiter but weighs 28 times more. It takes over 25 years to complete a single orbit around its star, HD 206893, at a distance of 9.6 astronomical units. Another planet also shares this star system.

The newly found exomoon itself is enormous, with a mass equal to 0.4 times that of Jupiter. It completes a full orbit around HD 206893 b in roughly nine months. A team led by French astronomer Quentin Kral made the discovery using the VLTI/GRAVITY instrument at the European Southern Observatory in Chile.

This breakthrough follows NASA’s recent announcement confirming 6,000 exoplanets. Over 8,000 additional candidates remain unconfirmed, showing just how much more there is to explore beyond our solar system. The detection of this exomoon provides direct evidence that moons exist around planets in other star systems. With advanced instruments like VLTI/GRAVITY, astronomers can now study these distant objects in greater detail. The discovery also highlights the growing number of confirmed exoplanets, expanding our understanding of planetary systems across the universe.