It might not be bright red, but Rudolph's nose really does glow. These thermal images of reindeer acquired by scientists show that Santa's flying friends have incredibly warm noses.
Because they live in cold climates, the noses of reindeer have adapted to have an increased blood flow to prevent them from freezing. In turn, that means they remain sensitive enough to identify food and keep them fed. For once, a Christmas story isn't entirely based on make-believe! [New Scientist]