# Massive exomoon detection ignites debate over what constitutes a moon

Astronomers have identified a candidate for a large exosatellite—a moon orbiting a planet outside our solar system. This finding challenges current definitions of what qualifies as a moon versus a planet. The debate could reshape our understanding of planetary systems and their formation.

**Importance:** 3/5

## Sources

### Science
- [Nature](https://www.nature.com/articles/d41586-026-02299-6) — 2026-07-22