ScienceJuly 22, 2026

exomoon

/ˈɛksoʊˌmuːn/

Definition

A natural satellite that orbits a planet or another body located outside of our solar system.

Etymology

The word is a portmanteau formed by prefixing 'exo-' (derived from the Greek 'exō', meaning 'outside') to the noun 'moon'. It follows the same linguistic pattern established by 'exoplanet'.

In the news

The term is used here to describe a potential massive object orbiting a brown dwarf, challenging existing definitions of what constitutes a moon. Its discovery is significant because confirming its identity would mark a breakthrough in detecting satellites in distant stellar systems.

‘Super weird’ object may be space’s first confirmed exomoon

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