Moonlet

{{Short description|Small natural satellite orbiting a planet}} {{Redirect|Minor moon|moons of minor planets|minor-planet moon}} [[File:PIA11672 Giant Propeller in A Ring.jpg|thumb|The 400-meter moonlet Earhart in Saturn's A Ring, just outside the Encke Gap]] [[File:Earthart ropeller.jpg|thumb|Another image of Earhart]] [[File:Bleriot (moon).jpg|thumb|Another moonlet named Bleriot]] [[File:Santos-Dumont propeller.jpg|thumb|A moonlet named Santos-Dumont]] thumb|A moonlet in Saturn's A ring

A '''moonlet''', '''minor moon''', '''minor natural satellite''', or '''minor satellite''' is a particularly small natural satellite orbiting a planet, dwarf planet, or 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.<ref name="O.C. Winter 2007">{{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 }}</ref>

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),<ref name="Tiscareno2006">{{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 }}</ref><ref name="Sremcevic2007">{{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 }}</ref> and those in the F Ring<ref>{{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 = }}</ref> * Occasionally asteroid moons, such as those of 87 Sylvia<ref name="Marchis05">{{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 }}</ref> * Flashes seen near Jupiter's moon Amalthea that is likely debris ejected from its surface<ref>{{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 }}</ref> * Subsatellites<ref>{{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}}</ref>

==See also== {{wiktionary}} * Minor-planet moon * Natural satellite * Ring system

==References== {{reflist}}

==Further reading== *[https://books.google.com/books?q=moonlet&btnG=Search+Books Google Book Search for "moonlet"]

== Links == [https://content.cld.iop.org/journals/1538-3881/135/3/1083/revision1/aj262114_mrt2.txt List of moonlets]

Category:Asteroid satellites Category:Moons of Saturn Category:Moons