Saturn's Possible New Moons

There have been many observations that seem to indicate additional small moons close to Saturn. None have been confirmed, however. Most if not all will probably turn out to have been observational flukes.

Facts

• The image above shows Epimetheus on the left and S/1995 S 3 on the right.

   

• Here are the provisional designations and orbital radii of some of the reported but as yet unconfirmed and unnamed moons of Saturn:
  

                         Distance
            Designation    (km)
            -----------  --------
            S/1981 S 7
            S/1981 S 10
            S/1981 S 11
            S/1981 S 14   200000?
            
            S/1981 S 15   174000
            S/1981 S 16   220000
            S/1981 S 17   231000
            S/1981 S 18   185000
            S/1981 S 19   186000
            
            S/1995 S 1    137450
            S/1995 S 2    139700
            S/1995 S 3    141050
            S/1995 S 4    146450
     
            S/1995 S 5    140060
            S/1995 S 6    139910
            S/1995 S 7    139440

   

• It is possible that some of these are actually the same as some of the known satellites (e.g. S/1995 S 1 may be Atlas and S/1995 S 2 may be Prometheus or S/1995 S 1 may be Pan and S/1995 S 2 one of the others); better orbital determinations will be needed to sort it out. IAUC 6243 confirms the probable identification of S/1995 S 2.

   

• The orbit of S/1995 S 7 is "indistinguishable" from that of S/1995 S 2 (= Prometheus) but S/1995 S 7 trails behind by 15 degrees.

   

• S/1995 S 3 orbits just outside the F ring and is apparently a shepherd moon. There are two other F ring shepherds ( Prometheus and Pandora), the presence of a third may account for the F ring's braided appearance.

   

• IAUC 6243 indicates that S/1995 S 5 and S/1995 S 6 may be just clumps or arcs of ring material rather than true satellites.

   

• These objects, if they are real, are all very small, just a few tens of kilometers in diameter.

   

• Ring plane crossings are particularly favorable for seeing small moons since the normally bright glare of the rings is absent. 13 of Saturn's 18 known moons were discovered during ring plane crossings.

   

• It now appears that none of these are real. They are most likely just short-lived clumps of material.

   

• All doubt should be laid to rest with the arrival at Saturn of the Cassini spacecraft in 2004.