Up until 1995, moonlets were only hypothetical components of Saturn's F-ring structure, but in that year, the Earth passed through Saturn's ring plane. The Hubble Space Telescope and the European Southern Observatory both captured objects orbiting close or near the F-ring. In 2004, Cassini caught an object 4–5 kilometers in diameter on the outer ring of the F-ring and then 5 hours later on the inner F-ring, showing that the object had orbited.[1]
Several different types of small moons have been called moonlets:
^Fieseler P. D.; Adams O. W.; Vandermey N.; Theilig E. E.; Schimmels K. A.; Lewis G. D.; Ardalan S. M.; Alexander C. J. (2004). "The Galileo star scanner observations at Amalthea". Icarus. 169 (2): 390–401. Bibcode:2004Icar..169..390F. doi:10.1016/j.icarus.2004.01.012.