It has long been a staple of science fiction and paranoid conspiracy theorists of the UFOlogist bent that a hypothetical planet occupying Earth's orbit but lurking opposite us on the other side of the Sun unprovably exists. Because hey...

How could we ever know?

Well. We could measure the gravitational effects our supposed evil twin would have on the movements of Venus and Mars, our nearest planetary neighbours as they go by where it just might be. Aaaand... it doesn't seem to have any.

So maybe it's smaller, or not as dense. Or something. We can't see it, so we can't know for sure.

Since the Earth's orbit is elliptical rather than circular, chances are good that one of our armies of amateur astronomers would have caught at least a glimmer of it.

But hey! Lack of proof doesn't constitute evidence to the contrary!

Unmanned spacecraft expeditions (the Venera, Pioneer and Magellan series, in particular) to that neck of the woods have had ample opportunity to report on the scenery during fly-bys, their structures bristling with very sensitive detection and sensory equipment and found nothing there.

Yeah, but who's in charge of those space agencies? The government! If you don't think they'd keep this sort of news from the public, you must be naive. Or one of them!

Listen, let's be fair: you leave me alone and I'll assert that there's a very small possibility that Gor actually exists, slave-maidens and all.

Oh thank God...

Now git! A quick web loony-search reveals that other names for hypothetical bodies across the big yellow from us include Orgon (without the "e") and the imaginatively-named "Planet X."