So toasty.
It's cold down in Antarctica, so penguins have to huddle together to keep warm.
IvanMikhaylov/IvanMikhaylov
Now scientists have modeled how emperor penguins stay so close together in their cosy huddles.
It only takes one penguin to move 2cm in any direction for the surrounding penguins to move too. This has a knock on effect, sending waves throughout the huddle.
The waves also mean that smaller huddles can eventually become much bigger.
2cm is roughly double the thickness of a penguin's insulating feather layer. That suggests penguins in a huddle are just barely touching each other, allowing each penguins' outer feathers can still do their job properly too.
Emperor penguins are the only vertebrate species that breed in the -50C temperatures of the Antarctic winter, so keeping warm is a priority.
Male penguins are solely responsible for keeping their single egg warm throughout the winter, when females go out to sea to feed.
They hold the egg in a pouch above their feet. Luckily, a penguin's body temperature in the middle of a huddle can reach 37C.
