Winter, in The Atlantic: A bald eagle sits on a branch over the Des Moines River, in downtown Des Moines, Iowa, on January 8, 2013. Iowa's cold, icy winters drive the birds to rivers to forage for food when inland waters freeze over. (AP Photo/Charlie Neibergall)
The bottom of the McMurdo Dry Valleys is one of the rare iceless places on Antarctic, is covered in polygonal patterns similar to those of a dried-up pond. Extreme temperature variations from summer to winter, when a six-month night envelops the continent and makes temperatures drop by 90°F (32°C), cause ice buried in the ground to freeze and thaw, creating this strange mineral tapestry. Patterns utterly similar to those of the Dry Valleys can be seen in the polar regions of the planet Mars.