Astronomers Discover the First Known Moon Outside our Solar System—and What a Moon it Is - Yahoo

What the report says

Time reported that astronomers have identified what is described as the first known moon beyond the solar system, citing a new paper in Nature. The object was found in the CD-35 2772 system, about 71 light-years away, by a team using the European Southern Observatory’s Very Large Telescope in Chile. The reported discovery is notable not only because exomoons have long evaded confirmation, but because this candidate is extraordinarily large: at least about Jupiter’s mass.

The object appears to orbit a brown dwarf, a gaseous body about 33 times Jupiter’s mass that is larger than a typical planet but not massive enough to become a star. Time said the brown dwarf itself orbits a star in the system and was first found in 2011. Kevin Hoy, the study’s lead author and an ESO student in Chile affiliated with Universidad Diego Portales, told Time that such bodies sit in a blurred category between ordinary planets and the smallest stars.

Unlike many exoplanets, which are often detected through starlight dimming during transits or by the gravitational wobble they cause in their stars, this exomoon was inferred from movement in the brown dwarf. Hoy’s team used radial velocity measurements to detect the wobble and estimate the companion’s mass.

The finding matters because it expands the search for moons beyond Earth’s neighborhood and complicates simple labels such as planet, moon and star. Time noted that more than 6,000 exoplanets have been detected since 1992, while confirmed exomoons had remained absent. Hoy’s team is also pursuing another candidate, and future searches may benefit from ESO’s Extremely Large Telescope, expected to begin operations in 2029.