# Astronomers spot exomoon candidate almost as massive as Jupiter A giant moon candidate discovered outside our Solar System. - **Source:** [www.theregister.com - Articles](https://brifing.si/source/2c34ea50-d341-4a10-925d-12c012a9ad10) - **Published:** 2026-07-22 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/b865196e-4d9d-42fa-9b06-86dfa63ff74c ## Giant Moon Candidate Astronomers have discovered a moon candidate outside our Solar System that is nearly as massive as Jupiter. The discovery was announced in a study published in Nature. The candidate orbits a brown dwarf in a system located about 73 light-years away. ## Definitional Gray Area The discovered object sparks debates over whether it is a moon or a planet. As massive as Jupiter, it orbits a brown dwarf but not a star. This challenges traditional definitions and places it in a unique category. ## Brown Dwarf Dilemma Brown dwarfs fill the gap between gas giants and small stars. They are not massive enough to sustain hydrogen fusion but can fuse deuterium. This makes them a special case in astronomical classification. ## Radial Velocity Method Researchers used the radial velocity method, which detected the first exoplanet in 1995. This technique identifies gravitational 'wobbles' caused by orbiting objects. Data indicates the presence of at least one satellite candidate. ## Unstable System Data modeling shows that a two-satellite system is possible but highly unstable. The discovered object completes an orbit every 170 days and has a mass about 90% that of Jupiter. ## Future Research This discovery is a significant step toward uncontroversial exomoon detection. However, more advanced instruments are needed to find smaller, Earth-like moons. The finding has sparked new debates in the astronomy community. ## Sources covering this story - https://www.theregister.com/science/2026/07/22/astronomers-spot-exomoon-candidate-thats-almost-as-massive-as-jupiter/5276419 — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._