The phrase "small moon" refers to a celestial body that orbits around a planet, but it is smaller in size compared to the main moon.
Sentences with «small moon»
But the discovery of so many small moons changes this. (newscientist.com)
The end result: one big moon alone in an orbital space once occupied by several smaller moons. (sciencemag.org)
As astronomers discover increasingly smaller moons, they will have to address the question of what exactly qualifies as a moon. (scientificamerican.com)