A combination of the words "smoke" and "fog," smog is a kind of air pollution that plagues cities throughout the world. Smog can form in almost any climate but is worse during periods of warm, sunny weather, when it can build up to dangerous levels and cause a number of health problems. It has even led to acute incidents in which thousands of people in a single metropolitan area have been killed. In what city did the Great Smog of 1952 kill approximately 4,000 people over a four-day period?
Back in the day
Pluto was discovered by the astronomer Clyde Tombaugh at the Lowell Observatory in Arizona while he was searching for "Planet X," a hypothetical planet that was believed to exist beyond Neptune. Pluto was long regarded as a planet, but following the discovery of other, larger Kuiper belt objects, astronomers recognized the need to reclassify Pluto. In 2006, the International Astronomical Union ended official recognition of Pluto as a planet. What is Pluto's current classification?
Born on a day like today
Morrison is an African-American writer and former editor for Random House whose work helped bring African-American literature into the mainstream. In 1988, she won the Pulitzer Prize for Beloved, which is now included in the canon of American literature, and she was awarded the Nobel Prize in Literature in 1993. Her fiction is noted for its poetic language, lush detail, and emotional intensity. Why did she call Bill Clinton "the first Black president"?