The Science Behind Santa's Christmas Eve Journey

With billions of children to visit in just one night, how does Santa make it to every house? And how does he fit down the chimney — assuming your house has one. Astrophysicist Neil De Grasse Tyson talks to David Greene about the science of Santa.

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DAVID GREENE, HOST:

Rudolph the Red-Nosed Reindeer, as we all know, has a very shiny nose. And so would you, if you were at the head of a team of reindeer bolting across the night sky, helping Santa deliver Christmas presents to two billion children in a single night. Now, to help us understand how Santa manages to pull this off every year, we're joined by a friend of this program, astrophysicist and science guru Professor Neil deGrasse Tyson. And happy holiday to you, Professor Tyson. Thanks for coming on again.

NEIL DEGRASSE TYSON: Thank you. You know, you guys ask me about everything. Man.

GREENE: Well, you know everything. I mean, what do you want us to do? Well, this will be particularly interesting, I think, to a lot of people because it's - I mean, I'm sure that Santa employs some Christmas magic that's beyond our understanding to get all this done. But there must be some science involved, too, right?

TYSON: Well, a couple of things. Let's back up for a minute. So, Rudolph's nose...

GREENE: Right.

TYSON: ...now, to me, the word shiny means it reflects light. If you only reflect light, that's not really good to lead the way through the darkness of the night.

GREENE: 'Cause there's no light to reflect.

TYSON: You have to radiate light. So, let's presume that his nose actually radiated red light. Well, it turns out red light is ideal for getting through foggy, cloudy nights, because red light penetrates through fog better than blue light. And that's why, for example, they don't want you to put on your brights when you're driving through fog. The brights are bluer than your low beams. So, the fact that Rudolph has a red nose, that's awesome.

GREENE: You're saying Santa found the right reindeer.

TYSON: Yes, he did. (Laughing) Rudolph's brother, who had a blue nose, no. That would not have worked.

GREENE: You know, Santa has to go really, really, really fast to get to all these places in the world. I mean, is there a sense for what he's doing?

TYSON: OK. So, now, yeah. So, it turns out if he traveled the speed of light, you know, light can encircle the Earth seven times in one second.

GREENE: Seven times in a second, OK.

TYSON: Yeah, light is awesome. Problem is: We all live within Earth's atmosphere. So, if you could go that fast through the atmosphere, then you'll just burn up. And I learned from speaking to an expert in comic book heroes that the Flash has atmospheric separators in front of him when he goes quickly from one place to another so that he does not burn up.

GREENE: So, Santa could have atmospheric separators, in theory.

TYSON: He could have atmospheric separators. So, now, you can go keep doing this calculation, have him go to every home. So, I realized that what he really needs is that - what they have in that movie "Monsters, Inc."

GREENE: Yeah.

TYSON: You remember that movie where...

GREENE: I do, but remind me.

TYSON: ...just manufactured doors. And the door in the "Monsters, Inc." factory is the door of the children's closet. And you just carry the door home with you. You go through that door, and you show up in the kid's closet and terrorize them in their sleep, because they're monsters, of course.

GREENE: And if he can go in these secret doors in all the houses that don't have chimneys, I mean, that's - he's able to travel magically into a lot more homes.

TYSON: Yeah, so, in that point, it's not magic. What "Monsters, Inc." never told you is that they're essentially wormholes.

GREENE: So it is possible that he's just up there doing kind of a lap around the Earth to kind of get the - do the photo shoot, and he's actually delivering all these presents in some other way, using wormholes and other devices.

TYSON: Yeah, he could be up there just for show. You know NORAD, right?

GREENE: The military - the folks who track flying objects.

TYSON: Yes. These are the folks that track missiles coming in from the Cold War threat. After the Cold War, you know, they said: Well, what else are we going to do? So, at the 24th, you go to the NORAD website, and they track Santa from the North Pole. You can know where Santa is at all times.

GREENE: You know what's really interesting about all this, this could explain why the kids have never been able to catch him coming down the chimney. I mean, maybe he's got the kids distracted by that, and he's actually getting in in some other way.

TYSON: You know, that's brilliant. That's brilliant, because he has to keep telling people to look at the chimney, and then he sneaks in another way. He creates a distraction. Yeah, I'll go into that. Yeah.

GREENE: Yeah, let's work on that theory. Well, I hope you get everything you wish for. Neil deGrasse Tyson, thanks for talking to us, as always.

TYSON: Thank you. Always good to be on with you.

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