Infrared Images Reveal Frigid, Purple Penguins
By Nadia Drake
Emperor Penguins with blue bellies, green beaks, and red eyes huddle over a patch of black snow — a multicolored Antarctic landscape, as seen through the eye of an infrared thermal imager.
The psychedelic colors, which correspond to different temperatures, reveal that much of a penguin’s outer surface is cooler than the surrounding air — except, of course, for their unfeathered eyes, beaks, and feet.
“Most of the body that is covered by thick plumage was found to be, on average, 4 to 6 degrees C colder than surrounding air temperature,” said biophysical ecologist Dominic McCafferty of the University of Glasgow. Only the birds’ eyes measured above freezing. “At first, we were very surprised by this discovery,” he said.
The observations, reported today in Biology Letters, suggest that extreme radiative cooling draws heat from a penguin’s feathery surface. (On a clear, cold night, you can see the effects of radiative cooling in the frost that forms on windows, roofs, and grasses.) But because they’re insulated beneath layers of feathers and fat, the birds can still maintain a body temperature of about 39 degrees C (102 degrees F), even when shuffling through the -40 C Antarctic night…
(read more: Wired Science)
(images: Université de Strasbourg and Centre National de la Recherche Scientifique (CNRS), Strasbourg, France)