"In our solar system, the most massive moon is Ganymede, which is still extremely small compared to what we are inferring here."

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

Source: space
Source Link: https://www.space.com/astronomy/exoplanets/wobbling-exoplanet-hints-at-a-hidden-exomoon-so-massive-it-could-redefine-the-word-moon-altogether