There are no real windows, just some holes cut in the sides, like the portholes in a ship, but not round and not square, with rawhide holding the shutter s up on the outside.
The proof, which was published last week in Science, comes from a team of scientists from Uppsala University in Sweden and Californian Institute of Technology who drilled deep holes near the edge of the ice sheet.
A second important area is monitoring the size of the hole in the ozone layer above Antarctica, since this is an indicator of global ultra-violet radiation levels.