December 14, 2009 hours of daylight
The South Pole and the North Pole are unusual in that they never have 24-hour "day and night" cycles. During the southern summer, the South Pole is always tilted towards the sun, bathing it in light for 6 months. During the southern winter, the South Pole is always tilted away from the sun, leaving it in darkness for another six months. Same holds true for the North Pole but opposite seasons - southern summer is the same time as northern winter.
Sunlight 24 hours a day, 7 days a week, for 6 months of the year might sound cool. And it is! But it also messes with your sleep cycles. Under normal circumstances, your brain tunes itself to the cycle of light and dark you see each day and night. As light fades, your brain expects sleep; and when the sun comes back up, your brain becomes alert again. When you remove that dark part of the cycle, your brain gets confused and isn't sure when to get tired. This (combined with hard work 6 days a week) helps explain why everyone here has dark circles under their eyes!
Here is a time-lapse video I made to help illustrate the 24-hour daylight. I aimed a camera out the window at the ceremonial pole (look in the middle of the national flags to see the ceremonial pole itself). Images were taken at 45-second intervals. Watch the shadows of the flags; as the earth rotates you can see the shadows rotate as well. At a few times you might see blips of activity as people go out to take photos or workers do their jobs... and at other times, the weather became overcast and creates some dramatic lighting effects!