On this date in history:

In 1500, Brazil was discovered by Pedro Alvarez Cabral.

In 1889, about 20,000 homesteaders massed along the border of the Oklahoma Territory, awaiting the signal to start the Oklahoma land rush.

In 1914, Babe Ruth made his professional baseball debut as a pitcher for the Baltimore Orioles.

In 1915, during World War I, German forces became the first to use poison gas on the Western Front.

In 1970, Earth Day was first observed.

1972, Apollo 16 astronauts John Young and Charles Duke walked and rode on the surface of the moon for 7 hours, 23 minutes.

In 1985, Jose Sarney was sworn in as Brazil's first civilian president in 21 years.

In 1993, the Holocaust Memorial Museum was dedicated in Washington.

In 1994, Richard Nixon, the 37th U.S. president and the only one to resign from the office, died four days after suffering a stroke. He was 81.

In 1997, a 126-day standoff at the Japanese Embassy in Lima ended after Peruvian commandos stormed the building and freed 72 hostages held by the Tupac Amaru Revolutionary Movement. All 14 rebels were killed.

In 2004, former NFL star Pat Tillman, who turned down a lucrative contract with the Arizona Cardinals to join the U.S. Army Rangers, was killed in Afghanistan. (The U.S. military said later he was a victim of friendly fire.)

In 2005, Zacarias Moussaoui, the only man charged in the United States in connection with the Sept. 11, 2001, terror attacks, pleaded guilty and was sentenced to life in prison.

In 2006, Iraq's Parliament ratified the selection of Nouri al-Maliki as prime minister, ending a four-month political deadlock.

In 2010, Russia banned Scientology literature for undermining the traditional spiritual values of the citizens of the Russian Federation.

In 2013, Boston Marathon bombing suspect Dzhokhar Tsarnaev was charged with conspiracy to use a weapon of mass destruction resulting in death. (Eventually, Tsarnaev faced 17 federal charges in the April 15 attack that killed three people and injured more than 260.)

Copyright 2014 by United Press International