Wobbling exoplanet hints at a hidden exomoon so massive it could redefine the word 'moon' altogether

image via Space.com

January 22, 2026, 11:00 AM

• •A wobble in the orbit of exoplanet HD 206893 B indicates the possible presence of a massive exomoon.
• •The potential exomoon is estimated to be around 40% the mass of Jupiter.
• •The discovery was made using astrometry with the GRAVITY instrument.
• •This finding could redefine the definition of a moon and open doors for future exomoon discoveries.

Astronomers have detected a 'wobble' in the orbit of exoplanet HD 206893 B, suggesting the presence of a massive exomoon. This potential exomoon is estimated to be around 40% the mass of Jupiter, which is significantly larger than any moon in our solar system. The discovery, made using astrometry with the GRAVITY instrument, could challenge current definitions of what constitutes a moon. The team hopes this finding will pave the way for future exomoon discoveries.

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