Assertion: mercury's rotation | /r/HasProperty | synchronous
Facets:
Source sentences:
text: A similar effect would have occurred if Mercury had been in synchronous rotation: the alternating gain and loss of rotation over revolution would have caused a libration of 23.65° in longitude.
text: The theory that Mercury's rotation was synchronous had become widely held, and it was a surprise to astronomers when these radio observations were announced.