A look back at other sitting vice presidents who were running for the top job and debating on TV against the nominee of the opposition party: Gore in 2000, George H.W. Bush in 1988 and Nixon in 1960.

This week marks the 60th anniversary of the assassination of President John F. Kennedy. A new documentary breaks down the legacy of the Warren Commission, which was set up to examine the circumstances of the killing of a president.

Over 13 days beginning on Oct. 16, 1962, the U.S. and Soviet Union were at the brink of a nuclear conflict. But since the Cold War ended, some historical assumptions about the crisis have changed.

All week, On Second Thought has shared stories about people whose unsung contributions to the Apollo 11 mission 50 years ago. One of those pioneers is...