Transcript for Neil deGrasse Tyson on controversy over Apollo 11 movie 'First Man'

I just -- I must ask about this because about ten years ago you and I had a little dust-up because I was really upset that Pluto had been downgraded. By him. Oh, really. No -- It was him but he was the front of it. It was a lot of scientists. I -- I drove the getaway car. I didn't actually -- He didn't rob the bank but he drove the getaway car and he was the face of downgrading Pluto so I gave him a hard time and a new study says it should have never been downgraded. Yeah, so it's a planet. I -- What happened? I don't have a horse in this race. You know, briefly I think we need more words than just planet to describe what orbits a star. Given the diversity and the variance we have rocky planet, big ones, gash shouse, some inhappen table. We need 50 words rather than just one so I'm not in that fight. But you should just get over that. I will never get over that. But why can't Pluto discuss be a planet -- Our moon has five times the mass of Pluto. Do you know Pluto in its orbit crosses the orbit of Neptune. Ain't no kind of behavior for a planet. That's no way to behave. Or a dog. They named a dog -- That dog is drawn the same year Pluto the cosmic object is discovered. The same tenure in the hearts and minds of Americans so Americans are the biggest complainers about the demotion of Pluto but I think it's because of that damn dog. Okay, so on to another topic. The trump administration recently announced plans to create the space force which apparently would become the sixth branch of the military. Would that be helpful, do you think? Just I want to make it clear, because just because that suggestion came out of trump's mouth doesn't mean it's a bad suggestion, okay. So just because of that. But you're skeptical. No, to be clear. If you want to analyze all information in its own context. Space force. It's already a TV show. Did you complain when the air force separated from the U.S. Army? I wasn't alive. The U.S. Army air force and people said, command and control and air is different from command and control on the ground and the soldiers have to be different and know how to fly. The engineers have to be different, have to know aerodynamics and they peeled it off and nobody said why are we doing it. It was a natural progression in the theaters of operations of war. You like this? No, I'm just not -- I don't own to it and if you're going to do it, throw in asteroid defense while you're at it because that could render us all extinct and how about clean up all that space debris that could interfere with commerce. Space assets are huge. They should bring you in. We're all walking around on the surface of our Earth with our gps and everything is copping down from space. Got my DirecTV and Uber is an entire industry that exists only because of gps satellites as well as tinder. Want to know who to mate in 24 hour, gps -- I bet if the people who invented gps knew that's how that was going to be used, I don't know if -- And it was -- a black woman actually who -- Okay. A black woman did all of that. No, no, no. I'm just saying -- I'm just saying, so it's not as crazy as it sounds. It's just the name. I think the name just -- The features they gave was muscle flexing, America, we're America. We're going to -- we're America and so but really space has been, quote, militarized since the '60s. In the sense that we've had reconnaissance satellites. Not laser guns or anything but just it's been in the service of military interests ever since we had the ability -- We're worried about a war in space between us and another country. You should worry more about a war in the ground -- I worry about that too. Right. This leads into your book because your new book is called "Accessory to war," and it talks about how astrophysics and the military have actually been intertwined for centuries. Millennia. Millennia. Go far enough back, captain cook when he went to the south pacific, his marching orders were, oh, there's an interesting astronomical phenomenon going on -- you can only see it from the south pacific. Here, go measure that so measured a transit to Venus. Venus passes us and if you learn that, he did that. Oh, by the way, flip over the page, oh, while you're there, here's some extra navigation tools developed by our astronomer, map every coastline you find and bring that back to us. Within two decades great Britain took control of Australia, of New Zealand, of tasmania, of Fiji island, of all those countries there have the union jack as an insert in their flag. This was knowledge of the universe brought to bear in navigation in the interests of empire building. Wow. We have been handmaidens for this activity since the beginning. I was uncomfortable about this for so long and realized not all conflict is bad. You're not going to go in the second World War -- hitler's rising -- I don't like war. That was the last good one. That's what I'm saying so I stopped judging war just outright saying all war is bad because the history of war is one where very important causes were fought against very bad people and so in this book it's an exploration of how science broadly but my field in particular has served the interests of nations. Okay. Wow. There's so much I think that we can be proud of as a country when it comes to space and it reminds me next year marks the 50th anniversary of Apollo 11's historic mission to the moon. Yes. You mentioned the moon earlier. There is a new movie coming out with Ryan gosling called "First man." About Neil Armstrong rather than a movie starring Ryan gosling. Yeah. That would probably -- Good luck with that. There's been controversy about this because -- Controversy? In the image of Neil Armstrong and buzz aldrin putting that American flag because this was a patriotic moment for this country putting that American flag in the moon that people are frustrated why wouldn't they highlight that in this movie. It's not even in the movie. Right, oh, it's about him. Yeah. So, a, B, do we all not know that mers did this? Does he not have the American flag on his -- is the American flag not on the lander? Does it not say nasa? No secret about who went to the moon. Ryan gosling is Canadian. That could throw that off. Ooh, ooh. So I don't -- I don't have a problem. By the way, what were the words on the plaque? Well, no, what did he say, one small step for man, one giant leap for mankind. He didn't say one step for man one large step for the united States. There's a unifying concept in the messaging that was put on the moon. If you're not sure look it up. Yeah. My gosh. We come in peace for all mankind. Don't say we come in peace for America. So the flag planting, ritualistic. But it's history also. But we know that. That's the point. You already know it. You can ask what is it accomplishing? I don't care one way or another really. It makes us feel better about ourselves. But also -- Americans -- Wait, we put a man on the moon putting boots -- and you're saying, I need the flag to feel better about myself. There's a guy on the moon. Pay attention to that. I think the flag should have been included but let's talk about something else. You're one of the nicest guys we know. Oh, thank you. One of the smartest. You played against type on "The big bang theory" -- This is a thing. Yeah, yeah. Let's take a look. Remember, I'm the guy who kicked Pluto out of the solar system. And it deserved it, so thank you, bye-bye. Whoa. That was fun. Let's see who else needs a Degrasse kicking. Bill Nye the science guy. Hey, bill, Neil Tyson, we got to talk. That was so good. I love that show. That just there like a week ago. I love it. You should be doing -- No, no, artists call me cappal a so I got -- they want to put science in their thing, I got to come. Before we go, I just want to say, happy birthday -- Is this -- Can I say it? Oh, do it. You're turning 60 this week. So is nasa. I'm the same age as nasa. Same age as nasa. I'm the same and as disneyland. We got you a little something-something to celebrate. Right there. Cake pops and guess what even Pluto -- Where is Pluto? Wait, wait. "Accessory to war" is out now and you'll all getting the book. You're all getting it.

This transcript has been automatically generated and may not be 100% accurate.