Popularized by adventure, fantasy, and sci-fi literature, Hollow Earth theories advance the notion that Earth has a hollow interior and, possibly, a habitable inner surface. Although direct knowledge of Earth's structure extends only 15 m (24 km) downâ€”the deepest humans have ever drilledâ€”the Hollow Earth hypothesis has long been refuted by the modern understanding of planet formation. However, in ancient times, subterranean realms seemed plausible and became linked with what religious concepts?
Honore de Balzac
Back in the day
Dachau was the first Nazi concentration camp and served as a model for others that followed. Over 200,000 prisoners from more than 30 countries were housed there, and records indicate that at least 32,000 inmates died in the camp, many from a typhus epidemic in 1945. Dachau was liberated by the 42nd Infantry Division of the US Seventh Army. What did the troops find when they entered the camp?
Born on a day like today
Duke Ellington was an American jazz musician and composer. Among his best-known short works are "Mood Indigo," "Solitude," and "Sophisticated Lady." He also wrote jazz works of complex orchestration for concert presentation and composed religious music, including three sacred concerts. Ellington toured Europe extensively, appeared in numerous jazz festivals and several films, and made hundreds of recordings. In 1969, he received the Presidential Medal of Freedom. What was his real name?