The Earth has TWO Moons ???

[Allan_L (Allan)]

According to the BBC show QI (just aired tonight 9/10/2012 ABC1 9:30pm)...
the Earth has two moons.
The second one only discovered in 1986
called Cruithne.

I must have been under a rock for the last 26 years because this is the first i have heard of it.

Doing a google, Wiki confirms most of the story, but says it is now regarded as a planetoid, orbiting the sun (not the Earth) in about 1 year.
But it was originally thought it had a 770 year orbit of the Earth.

Cruithne is in a normal elliptic orbit around the Sun. Its period of revolution around the Sun, approximately 364 days at present, is almost equal to that of the Earth. Because of this, Cruithne and Earth appear to "follow" each other in their paths around the Sun. This is why Cruithne is sometimes called "Earth's second moon".[2] However, it does not orbit the Earth and is not a moon.

Cruithne orbits the Sun in about 1 year, but it takes 770 years for the series to complete a horseshoe-shaped movement, with the Earth in the gap of the horseshoe

[goober (Doug)]

It's a running gag in Qi. They keep correcting themselves each season. That sounds like an early episode.

[Poita (Peter)]

That's right, it was originally thought to be orbiting the Earth, but in fact orbits the Sun.
I remember that episode of QI from ages ago, had that American comedian that looks like he was the basis for the character design of 'Mo' from the Simpsons.