Telesto/təˈlɛstoʊ/ is a moon of Saturn. It was discovered by Smith, Reitsema, Larson and Fountain in 1980 from ground-based observations, and was provisionally designated S/1980 S 13. In the following months, several other apparitions were observed: S/1980 S 24, S/1980 S 33, and S/1981 S 1.
In 1983 it was officially named after Telesto of Greek mythology. It is also designated as Saturn XIII or Tethys B.
Telesto is co-orbital with Tethys, residing in Tethys' leading Lagrangian point (L4). This relationship was first identified by Seidelmann et al. in 1981. Another moon, Calypso, resides in the other (trailing) Lagrangian point of Tethys, 60 degrees in the other direction from Tethys. The Saturnian system has two additional trojan moons.
Exploration
The Cassini probe performed a distant flyby of Telesto on October 11, 2005. The resulting images show that its surface is surprisingly smooth, devoid of small impact craters.
Notes
^Calculated from Telesto's volume-equivalent sphere radius of 12.3±0.3 km given by Thomas et al. (2020)
^Calculated by multiplying Telesto's volume with its assumed density of 500 kg/m.
^ Transactions of the International Astronomical Union, Vol. XVIIIA, 1982 (confirms Janus, names Epimetheus, Telesto, Calypso) (mentioned in IAUC 3872)
Seidelmann, P. K.; Harrington, R. S.; Pascu, D.; Baum, W. A.; Currie, D. G.; Westphal, J. A.; Danielson, G. E. (1981). "Saturn satellite observations and orbits from the 1980 ring plane crossing". Icarus. 47 (2): 282. Bibcode:1981Icar...47..282S. doi:10.1016/0019-1035(81)90172-X.
