French researchers at the Pasteur Institute published early findings describing a novel retrovirus later identified as the cause of AIDS, a milestone in the fight against the epidemic.

Barbara McClintock's decades of work on genetic transposition, first dismissed, gained fresh momentum as researchers confirmed "jumping genes" across species.

A Soviet fighter jet destroyed a civilian Korean Air Lines Boeing 747 that had strayed into restricted airspace, killing all 269 people aboard.

Soviet officer Stanislav Petrov correctly judged a satellite warning of incoming US nuclear missiles to be a false alarm, likely preventing nuclear war.

Soviet officer Stanislav Petrov judged a satellite warning of incoming US nuclear missiles a false alarm, averting possible retaliatory launch.

Soviet officer Stanislav Petrov judged a satellite warning of incoming US nuclear missiles a false alarm, likely averting nuclear war.

US forces landed on the Caribbean island of Grenada in Operation Urgent Fury, toppling a Marxist government days after a bloody internal coup.