Astronomers have discovered the first known moon outside of our solar system, a massive exomoon roughly the size of Jupiter. This celestial body orbits a brown dwarf star in the CD-35 2772 system, located 71 light-years from Earth.
The discovery is prompting a re-evaluation of cosmic definitions, as the exomoon's sheer size challenges conventional classifications. While the brown dwarf itself was detected in 2011 using an ordinary optical telescope due to its substantial mass, detecting its exomoon required a more sensitive approach.
Using the radial velocity method, astronomers observed subtle wobbles in the brown dwarf's movement. The degree of these wobbles allowed researchers to calculate the exomoon's size. "Being the third wheel in this system makes us want to call it a moon," stated Hoy, a researcher on the project, in a release accompanying the study. He noted that, despite its mass, it differs significantly from the smaller, rocky moons found within our own solar system.
This discovery raises fundamental questions about astronomical nomenclature. The exomoon's Jupiter-like scale blurs the lines between what constitutes a planet and what defines a moon, pushing the boundaries of typical astronomical categorization within the CD-35 2772 system.