Elon Musk’s ‘Occupy Mars’ banner contains a crucial, but hilarious, mistake

"Occupy Mars," Elon Musk's Twitter feed read on Wednesday. But for the SpaceX CEO, who aims to build a city on Mars by 2050, the image may have made a rather crucial mistake.

The image, shared with Musk's 32 million Twitter followers, summarizes one of the space-faring company's main missions. Musk aims to transform humanity into a multi-planetary species, using the Starship to send up to 100 people at a time to the red planet. The "Occupy Mars" slogan has featured on SpaceX t-shirts, and Wednesday's photo harkened back to one of Musk's most ambitious ideas.

There's just one problem: that's not Mars. The image actually shows the moon during a lunar eclipse.

It's an easy mistake to make. A total lunar eclipse tends to lead to a reddish hue around the moon, as the wavelengths of light scatter in the Earth's atmosphere as they pass from the sun to the moon. But don't be fooled: among other differences, the moon is just 384,400 kilometers away, far closer than the approximately 255 million kilometers between the Earth and Mars.

Musk's followers were quick to point out the mistake. Among those was Neil deGrasse Tyson, who owns a t-shirt with the correct planet in place.

"To be totally frank, I did an image search on my phone & posted without looking closely," Musk wrote in response.

Musk also noted that his Twitter banner image does show the correct planet, with Mars gradually terraforming over time:

Just like "Occupy Mars," this image also captures another of Musk's long-term ideas.

For the initial colonization phase, Musk has proposed sending up to one million tons to the surface of Mars. The Starship, currently under development at the Boca Chica facility in Texas, is capable of sending up to 100 people or 100 tons on this trip. SpaceX is aiming to build 1,000 Starships to fuel its ideas. Musk has suggested the plan could cost up to $10 trillion, depending on the eventual price of sending a ton to orbit with the Starship.

From there, the plan would be to build out a city with up to a million people. They would need to develop industries and become self-sustaining. Musk has suggested that the price of a ticket to Mars could come within the six-figure range, comparable to that of a house in the United States. Loans may be available for people to take up the offer, then pay back by working on Mars.

In the far-flung future, Musk has talked about the possibility of terraforming the planet to make it into a more hospitable place. One idea would be to heat the planet at the poles and release its carbon dioxide stores, which means humans could walk around the surface with just a breathing apparatus. Releasing these stores could involve nuclear fusion explosions with low fallout.

Perhaps little wonder, then, that SpaceX now sells a "Nuke Mars" t-shirt.

It's not guaranteed that Musk will see this plan through to the end. Speaking at Satellite 2020 in Washington, D.C., Musk warned that the current pace of innovation wouldn't be enough to actually complete the colonization project.

“The thing that concerns me the most right now is that unless we improve of rate of innovation dramatically, then there is no chance of a city on the face of the Moon or Mars,” Musk said. "This is my biggest concern."

Whether it's the moon or Mars on the shirt, there's a chance humanity might not occupy either.