The discovery was announced on 22 July by the European Southern Observatory (ESO), which operates the VLT telescope in Chile, where the observations were made.

The new celestial body, which the team of astrophysicists has designated an ‘exosatellite,’ orbits a brown dwarf; that brown dwarf, in turn, orbits the star CD-35 2722, which has about half the mass of the Sun.

“The exosatellite is clearly massive enough to be a planet, but it does not orbit a star [like planets do], even though it orbits an object that itself orbits a star. The fact that it is located at the third level of this [stellar] system leads us to identify it as a moon, even though it bears no resemblance to the small, rocky moons we see in the Solar System,” said the study’s lead author, Kevin Hoy of Diego Portales University in Chile, as quoted in an ESO statement.

For years, astronomers have unsuccessfully attempted to confirm the existence of natural satellites outside the Solar System.

Detecting them in other planetary systems “could help us better understand the diversity of their formation and evolution,” noted the ESO, an astronomical organisation of which Portugal is a member state.

“The satellite we appear to have identified is a giant gaseous body orbiting a high-mass companion that, in turn, has several times the mass of Jupiter,” added another researcher on the team, Alice Zurlo.

The new celestial object has at least the same mass as Jupiter, the Solar System’s largest planet, while the brown dwarf has more than 30 times Jupiter’s mass. Scientists were alerted to the new celestial body when they detected small oscillations in the brown dwarf.

The results of the discovery were published in the scientific journal Nature.