An international team of astronomers has reported the first discovery of a moon outside the Solar System, according to a research report published in Nature. The object was identified in the CD-35 2772 star system, 71 light-years from Earth, using the European Southern Observatory’s Very Large Telescope in Chile. Researchers describe the finding as a milestone for space science.

Scientists said the newly found moon has a mass at least equal to Jupiter’s. It orbits a brown dwarf rather than an ordinary planet; the brown dwarf is about 33 times larger than Jupiter and cannot generate the nuclear power needed to become a star. Lead author Kevin Whai of Diego Portales University said brown dwarfs occupy a position between ordinary planets and the smallest stars.

The brown dwarf was detected with an optical telescope in 2011, but the moon could not be seen directly from 71 light-years away. Whai’s team used the radial-velocity method to measure gravitational motion in the brown dwarf and confirm the moon’s presence and size. Researchers are seeking another possible moon, while the planned Extremely Large Telescope is expected to improve future searches.