Kieran Mulvaney

After Lewis and Clark's famed journey, these other explorers set out to document what lay beyond the frontier.

Since the Apollo missions began, space programs have offered a unique perspective on our home planet.

In 1954, the Giants' Willie Mays made a catch that wowed the nation—and became a legendary moment in baseball history.

“Shall we be thought mad?” expedition leader Salomon August Andrée wrote in his journal, just before he perished.

The Keeling Curve was among the earliest charts showing that carbon dioxide levels in Earth's atmosphere were on a steady uptick.

Check out some moments that drove the national conversation around climate change.

When an Uruguayan rugby team crashed in the Andes on October 13, 1972, cannibalism helped some survive two months in harsh conditions.

A disastrous 1879 Arctic expedition finally confirmed there was no open ocean at the top of the world—although warming waters could eventually make it possible.

From boots to sleeping bags, see how equipment that Edmund Hillary and Tenzing Norgay used in the first ascent of Mount Everest compares to what climbers use today.

Tens of thousands of shipwrecks lie lost and forgotten on the sea floor—but efforts to locate and explore them have seen great advances.

From ad-hoc 'bucket brigades' to steam-powered fire trucks, firefighting has seen steady advances, while climate change-fueled fires present new challenges.

In 1845, two ships left England to navigate the fabled Northwest Passage connecting the Atlantic and Pacific Oceans. Then they vanished without a trace.

What happened to the Franklin expedition remains unclear, but cannibalized remains were identified as belonging to third-in-command James Fitzjames.

A fierce 1708 battle caused the Spanish galleon to sink—along with its $20 billion worth of gold, silver and emeralds.

The discovery of Ernest Shackleton's ship at the bottom of Antarctica's Weddell Sea recalls a grueling expedition when men endured entrapment, hunger, frigid weather, angry seas—and near madness.

The March 8, 1971 fight between Muhammad Ali and Joe Frazier unfolded against the backdrop of a nation tearing itself apart over civil rights and the war in Vietnam.

In the early 1920s, 25-year-old Ada Blackjack survived two years on the frigid Wrangel Island after a failed expedition to claim the island for Canada.

As Adolf Hitler and the Nazi Party loomed over Europe, an American and a German boxer squared off in the ring. They'd meet again two years later.