Bill Nye thinks you'd have to be on drugs to believe Mars could ever be habitable for humans.
"This whole idea of terraforming Mars, as respectful as I can be, are you guys high?" the science educator asked in an interview with USA TODAY.
"We can't even take care of this planet where we live, and we're perfectly suited for it, let alone another planet."
Nye is a respected science communicator, so his opinion on the viability of Mars terraforming plans carries some weight. He also has some pretty solid arguments.
"It's not reasonable because it's so cold," he told USA TODAY.
"And there is hardly any water. There's absolutely no food, and the big thing, I just remind these guys, there's nothing to breathe."
Nye isn't alone in his thinking, either - noted astrophysicist Neil deGrasse Tyson, another well-known science advocate, also believes any plans to make Mars livable for humans are absurd.
In Musk and Hawking's opinions, we can and should exhaust all options for transforming Mars into something of an Earth 2.0.
And they have some pretty compelling reasons, ranging from climate change to the notion that becoming an interplanetary species is the next step in human exploration.
While Nye really couldn't have been more clear about his opinion on terraforming Mars in the USA TODAY interview, he did also say he believes we should send astronauts to explore the Red Planet.
And who knows? Maybe they'll find something there that moves the Science Guy from the camp of the terraforming skeptics to that of the believers.