moonlet

{{Short description|Small natural satellite orbiting a planet}}

File:PIA11672 Giant Propeller in A Ring.jpg in Saturn's A Ring, just outside the Encke Gap]]

File:Earthart ropeller.jpg]]

File:Bleriot (moon).jpg]]

File:Santos-Dumont propeller.jpg]]

File:A ring propeller and unseen moon.jpg

A moonlet, minor moon, minor natural satellite, or minor satellite is a particularly small natural satellite orbiting a planet, dwarf planet, or other minor planet.

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.{{cite journal

| first1= Othon C. |last1=Winter

| title= Moonlets wandering on a leash-ring

| journal= Monthly Notices of the Royal Astronomical Society: Letters

| year= 2007

| volume= 380

| issue= 1

| pages= L54–L57

| display-authors= 1

| last2= Mourão

| first2= Daniela C.

| last3= Giuliatti Winte

| first3= Silvia M.

| last4= Spahn

| first4= Frank

| last5= Da Cruz

| first5= Christiano | doi = 10.1111/j.1745-3933.2007.00347.x

|bibcode=2007MNRAS.380L..54W

| doi-access= free

| hdl= 11449/33832

| hdl-access= free

}}

Several different types of small moons have been called moonlets:

• A belt of objects embedded in a planetary ring, especially around Saturn, such as those in the A Ring, S/2009 S 1 in the B Ring ("propeller" moonlets),{{cite journal

| first1= Matthew S. |last1=Tiscareno

| title= 100-metre-diameter moonlets in Saturn's A ring from observations of 'propeller' structures

| journal= Nature

| year= 2006

| volume= 440

| issue= 7084

| pages= 648–650

| pmid= 16572165

| doi= 10.1038/nature04581

| bibcode= 2006Natur.440..648T

| display-authors= 1

| last2= Burns

| first2= Joseph A.

| last3= Hedman

| first3= Matthew M.

| last4= Porco

| first4= Carolyn C.

| last5= Weiss

| first5= John W.

| last6= Dones

| first6= Luke

| last7= Richardson

| first7= Derek C.

| last8= Murray

| first8= Carl D. | s2cid= 9688977

}}{{cite journal

| first1=Miodrag |last1=Sremčević

| title= A belt of moonlets in Saturn's A ring

| journal= Nature

| year= 2007

| volume= 449

| issue= 7165

| pages= 1019–1021

| pmid= 17960236

| doi= 10.1038/nature06224

| bibcode= 2007Natur.449.1019S

| display-authors= 1

| last2= Schmidt

| first2= Jürgen

| last3= Salo

| first3= Heikki

| last4= Seiß

| first4= Martin

| last5= Spahn

| first5= Frank

| last6= Albers

| first6= Nicole| s2cid= 4330204

}} and those in the F Ring{{cite journal

|first1 = Carl D. |last1=Murray

|title = The determination of the structure of Saturn's F ring by nearby moonlets

|publisher = The Science and Technology Facilities Council

|date = June 5, 2008

|journal = Nature

|url = https://hal-cea.archives-ouvertes.fr/cea-00930885/file/mur.pdf

|pmid = 18528389

|doi = 10.1038/nature06999

|volume = 453

|issue = 7196

|pages = 739–44

|display-authors = 1

|last2 = Beurle

|first2 = Kevin

|last3 = Cooper

|first3 = Nicholas J.

|last4 = Evans

|first4 = Michael W.

|last5 = Williams

|first5 = Gareth A.

|last6 = Charnoz

|first6 = Sébastien

|bibcode = 2008Natur.453..739M

|s2cid = 205213483

|url-status =

}}

• Occasionally asteroid moons, such as those of 87 Sylvia{{cite journal |first1=Franck |last1=Marchis |title=Discovery of the triple asteroidal system 87 Sylvia |journal=Nature |volume=436 |pages=822–24 |year=2005 |bibcode=2005Natur.436..822M |doi=10.1038/nature04018 |pmid=16094362 |issue=7052 |display-authors=1 |last2=Descamps |first2=Pascal |last3=Hestroffer |first3=Daniel |last4=Berthier |first4=Jérome |s2cid=4412813 |url=https://escholarship.org/uc/item/7nb376hk }}
• Flashes seen near Jupiter's moon Amalthea that is likely debris ejected from its surface{{cite journal

|author =Fieseler P. D.

|author2 =Adams O. W.

|author3 =Vandermey N.

|author4 =Theilig E. E.

|author5 =Schimmels K. A.

|author6 =Lewis G. D.

|author7 =Ardalan S. M.

|author8 =Alexander C. J.

|title =The Galileo star scanner observations at Amalthea

|date =2004

|journal =Icarus

|volume =169

|issue =2

|pages =390–401

|doi =10.1016/j.icarus.2004.01.012

|bibcode =2004Icar..169..390F

}}

• Subsatellites{{cite web |url=http://www.science20.com/robert_inventor/can_moons_have_moonlets_or_rings_moonlets_of_plutos_moons-154917 |title=Can Moons Have Moonlets? Or Rings? Moonlets Of Pluto's Moons? |publisher=Science 2.0 |first=Robert |last=Walker |date=17 April 2015 |access-date=9 April 2016}}