On this day (Jan. 17) 100 years ago, British explorer Robert Falcon Scott and four weary companions reached their long-sought goal — the South Pole. It was a bittersweet day for the party, perhaps more bitter than sweet, and a milestone that would eventually prove to be their undoing.

Not only had their two-and-a-half month march across a glacier, over the Transantarctic Mountains, and through blinding snow taken a toll on the men, but only the day before, on Jan. 16, the team discovered that what Scott had long dreaded had come true....