In 1984, paleontologists David Raup and Jack Sepkoski posited that mass extinction events are cyclical, happening about every 26 million years, and are often caused by large impact events—such as the asteroid that may have led to the end of the dinosaurs 65 million years ago. Some astronomers sought to explain the theory with Nemesis, a hypothetical companion star to the Sun about 1.5 light-years away. According to the hypothesis, how was Nemesis responsible for these extinction events?
Jerome K. Jerome
Back in the day
Rising 28,251 ft (8,611 m) between China and Pakistan, K2 is the second-highest peak in the world after Mount Everest. Severe storms make K2 more dangerous to climb, however, and it has never been summited in winter. Measured in 1856, it was not summited until nearly 100 years later. In 1954, Italians Achille Compagnoni and Lino Lacedelli reached the top with the help of crew members who carried oxygen to above 26,245 feet (8,000 m). What thwarted an American attempt just one year earlier?
Born on a day like today
A man of shifting alliances, Philip the Good ruled Burgundy at the height of its prestige and presided over one of Europe's most lavish courts. After his father was murdered during a meeting with the dauphin of France—the future King Charles VII—Philip formed an alliance with England but then broke it to recognize Charles as king and gain French favor. Phillip soon turned on Charles, however, sheltering his rebellious son, the eventual King Louis XI. Who was captured by Phillip's troops in 1430?