Astrophysicist, author, and science communicator Neil DeGrasse Tyson has in recent years earned himself a label with which he doesn't quite agree: pop-culture nitpicker.

“I got branded as someone who nitpicks,” Tyson said in a 2017 interview with Complex. “I took private offense at that. Here’s why: If you’re watching a Jane Austen period piece, and people come up to an English countryside home in a horse drawn carriage and somebody gets out of the carriage with tie dye bell bottoms, you would cry foul. You would say the costume designer had their head up their ass. You’d be praised for making that observation. But all of a sudden I’m a buzzkill.”

It started in 2013 when Tyson fired out a barrage of fact-checking tweets about the movie Gravity.

Tyson has since Tweeted about shoddy science in films such as Alien: Covenant, Guardians of the Galaxy: Vol. 2, and, surprisingly enough, Baywatch. But most recently, Tyson used his scientific literacy to weigh in on decidedly new territory — the medieval fantasy world of Game of Thrones. 

Here are a few of his tweets, along with a quick look at the science behind them. (Warning: spoilers ahead.)

Here, Tyson’s referring to a concept in physics called tension: the pulling force transmitted axially by something like a rope, cable, or chain. This force allows objects to be pulled or suspended in the air. But when there’s slack in the rope that means there’s zero tension. That also means zero pulling force.

So, considering there’s slack in the white walkers' chains, it’d be impossible for them to haul the dragon Viserion out of the water. Speaking of the reanimated Viserion, would blue fire really melt the wall?

This claim seems spot on (except for a couple caveats listed below).

Flames are produced through combustion, which is the chemical reaction between a fuel and a compound of oxygen. The general rule is: the hotter the flame, the cooler the color. Flames are reddish between 1,112 and 1,832 degrees Fahrenheit, orangish between 1,832 and 2,192 Fahrenheit, and yellowish between 2,192 and 2,552 Fahrenheit. Any hotter than that, flames enter the blue-violet end of the visible spectrum.

But — not to nitpick the nitpicker — there could be some other factors Tyson’s not considering here. First, the colors emitted by flames are sometimes determined by the molecules and atoms in the fire, not necessarily its temperature. And second, not everyone’s convinced Viserion is breathing fire at all. As Game of Thrones sound designer Paula Fairfield suggested to Vanity Fair:

“He’s just going at it and slicing with this. It's kind of like liquid nitrogen. It’s so, so cold. So imagine if that’s what it was, but it’s so cold it’s hot. That kind of thing.”

Either way, Tyson also tweeted about the biology of the Game of Thrones dragons.

Birds appear to be the ancestors of a branch of bipedal, carnivorous dinosaur called theropods. The forelimbs of these upright animals were mostly unnecessary to locomotion, so over time they were modified by evolution to serve other purposes — like flight.

Artist rendering of a theropod.

Capping off his Game of Thrones tweeting spree, Tyson left his followers with a not-so-subtle political message regarding one of the show's most significant cultural customs.