Editing Iapetus (moon) (section)

=== Overall shape ===
Current triaxial measurements of Iapetus give it radial dimensions of {{cvt|746|x|746|x|712|km||}}, with a mean radius of {{cvt|734.5|±|2.8|km}}.<ref name="Roatsch et al. 2009" /> However, these measurements may be inaccurate on the kilometer scale as Iapetus's entire surface has not yet been imaged in high enough resolution. The observed oblateness would be consistent with hydrostatic equilibrium if Iapetus had a rotational period of approximately 16 hours, but it does not; its current rotation period is 79 days.<ref name="Thomas2010"/> A possible explanation for this is that the shape of Iapetus was frozen by formation of a thick [[crust (geology)|crust]] shortly after its formation, while its rotation continued to slow afterwards due to [[Tidal acceleration|tidal dissipation]], until it became [[tidal locking|tidally locked]].<ref name="Science News" />