There's plenty to celebrate in Star Wars: The Empire Strikes Back, which has its 40th anniversary on May 21. Beautiful new landscapes, engaging world-building, and rambunctious puppets, to name a few. But, there's some darkness, too: hands getting chopped off, Han getting frozen, etc. The grossest moment, though, has to be when Luke Skywalker gets stuffed into a tauntaun sleeping bag.
We know Luke was in serious trouble, as he'd otherwise have frozen to death on the ice planet Hoth, and we'd suffer just about any indignity to save our boy Skywalker. But, jumpin' Jawas, Georgie. Luke definitely has PTSD from the time his friend sliced open his recently deceased ice-horse-lizard and shoved him inside, right?
But, would that even work? Was all of that trauma even worth it?
Let's find out.
THE GROSSEST MATH PROBLEM IN THIS OR ANY OTHER GALAXY
The common knowledge, when someone is suffering from hypothermia, is to keep them warm by sharing body heat. So Han's plan to keep Luke warm inside the recently deceased tauntaun makes sense on the surface. It's sort of like a nice thick coat — at least, from a certain point of view.
The question then becomes: How much heat does a dead tauntaun offer, and how long can we reasonably expect that heat to stick around? In order to answer that question, we first need to understand what happens to a body once it stops metabolizing.
Algor Mortis is the process by which a corpse's temperature equalizes with that of the ambient temperature of the surrounding environment. In most cases, this equates to cooling. (Side note: Algor Mortis would also make an excellent name for a character in the Star Wars universe.)
On average, a body loses heat at a rate of 1.5 degrees Fahrenheit every hour until it reaches ambient temperature. This process can last approximately 18 to 20 hours, in total. Which seems like a pretty long time and bodes pretty well for Luke's makeshift space heater. But don't get too excited just yet.
The rate of heat loss after death is relatively slow, normally, because the temperature difference between the warm, living body and the surrounding air is pretty minimal.
Newton's Law of Cooling dictates that the rate of temperature change in an object is proportional to the difference between its temperature and the temperature of the surrounding environment. In short, if the two temperatures are close to one another, the change is slow. If the two temperatures are more disparate, the rate of change is more pronounced. All of which makes intuitive sense when you think about it.
Most of what we know about temperature change in corpses relates to what happens in an average environment, and the ice world of Hoth is far from ordinary.
Even under the usual circumstances, there is some contention as to the exact rate of temperature change. Investigators often use body temperature to estimate the time of death but it's still just an estimate to get them in the ballpark. There are too many variables.
In our scenario, the variables are increased. We're dealing with an alien environment, and two alien species. The good news is, physics is universal, so we can use math to at least get us close.
In order to figure out just how long Luke could reasonably expect to survive inside the warm belly of a dead tauntaun, there are few things we need to know. We are going to have to make some assumptions. First, we're going to treat Luke as if he is human. Like, Earth human, and assume an average body temperature of 98.6 degrees Fahrenheit (37 Celsius). We also need to know the average internal temperature of a tauntaun and the temperature of the surrounding environment.
There are, of course, other variables to consider. Despite tauntauns being reptiles, they do have fur. Knowing the hair density of their fur would be valuable information, as that will have an impact on how well they regulate heat. Knowing their body fat content, whether or not they have blubber or something equivalent would also be good to know.
Unfortunately, we were not able to get in touch with any exo-biologists for comment, so we'll have to work with what we have.
While tauntauns were lizards, they clearly share some characteristics with mammals and it's reasonable to assume they were warm-blooded. A cold-blooded animal might be able to survive on the icy plains of Hoth, perhaps by freezing themselves during winter months like arctic frogs, but they wouldn't make good pack animals.
It's likely they have more in common with Earth's arctic mammals, all of which maintain similar internal body temperatures to humans.
With that in mind, we'll assume a starting temperature of 37 degrees Celcius for both Luke and the tauntaun.
It's worth noting here that Luke's temperature was probably a bit lower, as he was clearly suffering at least mild hypothermia after his run-in with the wampa and his trek through a blizzard. And the tauntaun had been dead for a couple of minutes before being sliced open... but we want to give Luke the best chance at survival, so we'll let it slide.
As for the ambient temperature, this is also hard to accurately determine. There was a storm going on at the time so the temperatures were probably lower than average. Still, Wookieepedia gives a low temperature of -60 degrees Celcius, so we'll go with that.
With temperatures that frigid, accompanied by howling winds, heat would be wicked away at an alarming rate. Without knowing all of the variables, like how thick the layer of fat is on a tauntaun, or how much it and Luke had cooled before he slipped inside, there's no way to make an exact calculation. But given what we see on screen, Luke doesn't have 18 to 20 hours — he has an hour or two at most before his core temperature falls into sever hypothermia territory.
What's worse, entering the tauntaun might have been a one-way trip. Heat irradiates away from an object via the surface, first. The tauntaun would cool more quickly than Luke would while tucked away in its gooey center.
Given enough time, Han might return from building a shelter or finding help, to discover Luke still alive, but entombed in a frozen beast, unable to escape his icy coffin.
Surviving freezing temperatures inside a freshly slain animal might work, at least for a little while, but we wouldn't recommend it.