evidence: The idea that the Earth is flat is nothing new, but the conspiracy theory seems to have gained a bit of extra momentum in recent weeks. [...] But Elon Musk - who knows more than a thing or two about rockets - has posed the obvious question: if Earth is flat, does that mean other planets are as well? The billionaire posted a tweet asking why there was no Flat Mars Society - taking a swipe at the Flat Earth Society which continues to peddle the idea that our planet resembles a pancake.