IT'S that time of year again, when corn fields become blank canvases and mysterious crop circles appear all over the countryside. But rather than attributing it to the warm weather and the corresponding growth of arable crops, some alien conspiracy theorists claim it is down to ETs and the arrival of mythological planet Nibiru. One shock theory claims crop circles are being left due to pressure created on our planet by the arrival of a mythological planet known as Nibiru or Planet X. The conspiracy theory dubbed the Nibiru Cataclysm has been circulated since 1976. Then, writer Zecharia Sitchin claimed that two ancient Middle Eastern cultures – the Babylonians and Sumerians – told of a giant planet – Nibiru – that orbited the Sun every 3,600 years. He based this on a translation of Sumerian writing – one of the earliest systems of writing in the world – which is not recognised by other scholars. Believers later linked this to Planet X – a hypothetical planet astronomers suggested could