This week's anniversaries span civil rights, science and disasters

This week marks anniversaries of a string of events that have shaped U.S. and global history, from pivotal moments in civil rights and medicine to milestones in space defense and devastating natural disasters. Between Sept. 22 and Sept. 28, observers will note anniversaries ranging from an attempted presidential assassination in 1975 to the discovery of penicillin in 1928 and recent climate and space missions that continue to influence policy debates.

On Sept. 22, 1975, Sara Jane Moore fired two shots in an unsuccessful attempt to assassinate President Gerald R. Ford outside a San Francisco hotel, narrowly missing the president. That date also recalls President Abraham Lincoln's preliminary Emancipation Proclamation in 1862, which declared enslaved people in rebelling states to be free as of Jan. 1, 1863 if the states did not end their rebellion. Historians say the proclamation transformed the Union war effort into a fight against slavery and set the stage for later constitutional changes. Other Sept. 22 anniversaries this week include the start of the Iran-Iraq war in 1980 and a deadly 1993 Amtrak derailment near Mobile, Alabama.

Sept. 23 and Sept. 24 bring reminders of how...