venus-sat

A satellite in the past has occasionally been observed revolving round Venus. It is not currently observed - for whatever reason. This satellite's orbital period has been measured as being nine days and seven hours. That is:- 9.292  Earth days. Its rotation period would be expected to be equal to its orbital period (due to "tidal locking"). The SUM of its orbital and rotation periods would equal 18.584 Earth days.  Below, we see a scan from The Annual Register for the year 1761, page 119 where one of the sightings of this satellite is reported, together with its orbital period. 

Since the above mentioned sighting, there have been quite a few subsequent sightings of a satellite of Venus (subsequently given the name of Neith). Here is a scan from The Dublin Review 3rd series, Volume 19, Jan to April 1888, page 193:-