Politics aside, it takes a hearty soul to survive in Alaska. The Discovery Channel's series “Alaska: The Edge of Life” (out on DVD) surveys some of the peculiarities of a land where the land sun shines only three hours a day in the depth of winter. Three times the size of Texas, the brutally cold state is home to 40 active volcanoes. Summers are short but the days are long, and even if Alaska ranks lowest among the 50 states in agricultural production, those long stretches of sunlight result in Guinness Book records for the size of vegetables. One farmer interviewed for the special proudly displayed a 100-pound cabbage. The scenery is amazing, from the forests and glaciers to the Northern Lights, dancing across the night sky from spring through fall.