MOON(S) OF VENUS

Venus (like Mercury) currently has no known natural satellite (moon).

But this doesn't mean we stop looking. As recently as 2009, astronomers completed a new survey searching for possible Venusian moons (with a lower size limit of about a kilometre).

However, Venus has had moon(s) in the past:
In 1672, Giovanni Cassini discovered a small object close to Venus. Re-observing the object in 1686, he declared it a possible moon of Venus. Many observations followed; including when a spot was seen to follow Venus during a transit across the Sun in 1761. However, some astronomers failed to find the satellite, despite determined observations.

In 1766, the director of the Vienna Observatory speculated that the “moon” was actually the result of an optical illusion but research carried on, and in 1977 its orbital period was calculated to be 11 days and 3 hours.

In 1884, the moon was declared to be a planet, which orbited the Sun every 283 days. The moon/planet was named Neith (after the Egyptian goddess of hunting and war).

The Belgian Academy of Sciences published a paper in 1887, reviewing every reported sighting of Neith. They determined that most of the sightings could be explained by stars (which appear on the sky in the vicinity of Venus).

And Venus was once again moonless.

More recently (2005), two Caltech researchers proposed that Venus had two moons in its early history, both caused by collisions with other bodies. Strong tidal forces from the Sun then caused the moons to be pulled out of orbit.

THAT'S NO MOON....

Quasi-satellites are objects which have a 1:1 mean-motion resonance with their host – that is, the planet and the satellites orbit the Sun in equal amounts of time (rather than the satellite orbiting the planet itself). The most well known examples are the Trojan asteroids of Jupiter.

2002 VE68 was the first quasi-satellite to be discovered around a major planet in the Solar System. It was discovered on November 11, 2002, however the possibility of retrograde or quasi-satellites was first considered in 1913. 2002 VE68 is included in the Minor Planet Center's list of Potentially Hazardous Asteroids as it frequently comes within 0.05AU of the Earth (this is 5% of the average distance from the Earth to the Sun, or about 7.5 million kilometres).

The asteroid also displays near-resonant behaviour with Mercury and the Earth. Simulations suggest that 2002 VE68 has been co-orbital with Venus for about 7,000 years (injected into its present orbit by the action of the Earth), but is likely to be ejected from orbital-resonance with Venus in the next 500 or so years.