Neil deGrasse Tyson is tired of people denying proven science. The renowned astrophysicist and head of the Hayden planetarium in New York City posted a video to Facebook containing "what may be the most important words I have ever spoken," he wrote in a post Wednesday.

In the video, Tyson reminisces on America's history, saying, "We pioneered industries," and lauds the discoveries and strides Americans made, calling science "a fundamental part of the country that we are." The title of the video, "Science in America," evokes a bit of Ronald Raegan's television ad, "It's morning in America." Both videos feature picturesque photos of America and the Capitol in Washington.

Read: Bill Nye, Bernie Sanders On Climate Change: Senator And 'Science Guy' Talk Global Warming On Facebook Live

But he's worried and maybe even angry.

"It seems to me people have lost the ability to judge what is true and what is not," he says to the camera before saying this lack of judgment mixed with power is the "recipe" for the "complete dismantlement of our informed democracy." The video includes a clip of Vice President Mike Pence calling for educators to teach evolution as theory instead of fact.

"I don't remember any time where people were standing in denial of what science was," Tyson says, calling science a means of finding the truth.

"It is truth, whether or not you believe in it. And the sooner you understand that, the faster we can get on with the political conversations about how to solve the problems that face us," he says before focusing his attention on climate change specifically. 

In a time when the president and his Environmental Protection Agency director have both denied climate change, Tyson's video reflects fears some Americans have, and fears many Facebook users voiced in the comment section of the post. The video had more than 10 million views just a day after it was posted. 

He left viewers with the encouraging message, "As always, but especially in these days, keep looking up."