The theory that the world might actually be flat has gotten a lot of attention over the last year or so. Many people, from athletes to rappers, have publicly claimed that the Earth is flat, one even started raising money to launch a rocket to try to prove Earth is flat.

On Tuesday, Elon Musk, CEO of the company SpaceX and one of the strongest supporters of travel to Mars asked a question on Twitter that many people have been thinking: "Why is there no Flat Mars Society!?" He tweeted this in reply to his own retweet about the sky on Mars above a photo of the Red Planet.

He’s referring to the fact that there’s a Flat Earth Society, for those who believe that the Earth is flat, rather than a sphere, but that there is no equivalent for Mars. The description of the Flat Earth Society on its website calls it, "A place for free thinkers and the intellectual exchange of ideas."

Other Twitter users have wondered this as well; they’ve even made illustrations that show the solar system with Earth as the only flat planet. Another users also asked why there’s no flat moon theory.

Astrophysicist Neil deGrasse Tyson tweeted over the weekend about the theory of a flat-Earth as well, specifically what a solar eclipse might look like if the Earth were indeed flat.

One person on the FES forum did ask, "What about other planets?" but the page says it has since been moved to "Complete Nonsense." So whether or not flat Earth believers also think Mars is flat or not, is a question unanswered.

flat earth forum This question about whether or not other planets are also flat was categorized as "complete nonsense." Photo: Screenshot from Flat Earth Society

There are other threads in forum on the site about whether or not other planets are also flat, like Earth, or whether they're spherical. The jury is out on this though, some people agree that other planets are flat like Earth, while others like the user pictures below, Lonesome Crow, who calls themselves a "legitimate flat earth believer," believe other planets are spherical.

other planets flat earth There is some conflict over whether other planets in addition to Earth are flat. Photo: Screenshot from Flat Earth Society

It’s unclear whether there’s a consensus among flat Earth believers that other planets are either flat or spherical, they seem divided over it at best and don’t have a specific stance on the topic on their website. The first mission to Mars, on schedule to be conducted by either Elon Musk and SpaceX or by NASA won't happen for another decade or so. But there are already photos of, and from the surface of, Mars and even once people make it to the planet, flat Earthers might not believe any findings from those missions. 

Update Wednesday, 2 p.m. EST: The Flat Earth Society responded to Musk's tweet on Tuesday evening and said that they do actually believe that Mars is round because "Mars has been observed to be round." The tweet then said they wish Musk has a "fantastic day."