ON THIS DATE

2012: American rhythm-andblues singer Whitney Houston—who emerged as a pop superstar in the 1980s, especially known for her soaring voice—died at age 48.

2011: Egyptian President Hosni Mubarak stepped down after nearly 30 years in power, following mass demonstrations that were part of the prodemocracy uprisings known as the Arab Spring.

1990: After serving 27 years in prison, Nelson Mandela was released, and he subsequently began negotiations with President F.W. de Klerk that ended apartheid in South Africa.

1975: British politician Margaret Thatcher was elected leader of the Conservative Party, replacing Edward Heath; she became Europe's first woman prime minister in 1979.

1969: American actress Jennifer Aniston, who achieved stardom on the popular television sitcom Friends (1994–2004) and launched a successful film career, was born.

1964: Sarah Palin—who, as

John McCain's running mate in the 2008 U.S. presidential election, was the first woman to appear on a Republican presidential ticket—was born.

1858: On this day in 1858 in Lourdes, France, 14-year-old Bernadette Soubirous, a miller's daughter, first had visions of the Virgin Mary that were authenticated by Pope Pius IX in 1862, initiating the cult of

Our Lady of Lourdes.

1847: American inventor Thomas Edison, who, singly or jointly, held a world record of 1,093 patents and who played a critical role in introducing the modern age of electricity, was born.

Pennsylvania Hospital, the first hospital in the United States, began admitting patients; it was cofounded by Benjamin Franklin.