Neil deGrasse Tyson might be the hippest astrophysicist around, tweeting a mix of shrewd, funny and profound missives to his more than 9.2 million followers. In a series of tweets that began on Sunday, he reminded his audience that he is also up on his television shows, thank you very much, including the massive hit Game of Thrones. And he’s got a few things to say about the science in the show, some good and some not so good.

“Everybody all caught up on #GameOfThrones? I have a comment or two, if anybody is interested…” he tweeted on Sunday. They were interested, according to the wide range of GIFs and memes—featuring Kit Harington as Jon Snow and Emilia Clarke as Daenerys Targaryen as well as Gene Wilder as Willy Wonka, plus Jon Stewart, Judge Judy, Barack Obama and the Cookie Monster—that signaled their impatience for him to begin.

“I thought the frozen dead dudes couldn’t swim, but aside from that…” deGrasse Tyson began. He explained that there’s some bad physics in Game of Thrones. “Pulling a dragon out of a lake? Chains need to be straight, and not curve over hill and dale,” he wrote.

But he followed it up with a compliment about some good biophysics in the show. “The Dragon Wingspans are sensibly large, as their body weight would require for flight,” he said. To drive the point home, he added that “the sensibly large wingspan of Dragons in #GameOfThrones contrasts with aerodynamically useless wings of Renaissance cherubs.”

The biology made sense as well, he added, comparing the show to an older fantasy book and movie series. “As in #LordOfTheRings, Dragons forfeited their forelimbs to make wings, like birds & bats.”

Next, deGrasse Tyson set aside his evaluations to point out a fun fact about “intriguing thermal physics” in the show. “BlueDragon breath would be at least a factor of 3X hotter than RedDragon breath,” he wrote.

His sequence seemed to be over about an hour after it began. But on Monday morning deGrasse Tyson added one more Game of Thrones–related tweet. It didn’t really have anything to do with science and at first glance seems out of place among the rest of his observations. He wrote: “In the #GameOfThrones Universe, to ‘bend the knee’ represents the very highest form of respect and loyalty.”

Normally, a random comment about what a gesture means in a fictional universe would tell us simply that even this astrophysicist has gotten into the nerdy weeds of fandom. But when the statement comes in the midst of a vociferous debate among athletes, the president, sports fans and the general public about what it means when players “take a knee” during the national anthem, the comment takes on a whiff of politics, whether or not that’s what Tyson had in mind.