23 times the Doomsday Clock moved

• The Doomsday Clock debuted as a graphic on the Bulletin of the Atomic Scientists in 1947, and gained popularity worldwide as a symbol marking the threat of an impending nuclear apocalypse. 
• It's now a symbol measuring how close humanity is to total destruction (per various causes). The closer the clock is to midnight, the closer we are to destruction. 
• The Cold War drastically affected the Doomsday Clock, as did President Trump's election.  
• Climate change and social media have also affected the time shown on the clock. 

Since the '40s, the Doomsday Clock has measured how far humanity is from the brink of total destruction. Every few years, the Bulletin of the Atomic Scientists releases a new time that represents the measurement. The closer to midnight the time is, the closer we are to the end.

Scientists having worked on the atomic bomb began publishing the Bulletin of Atomic Scientists in 1945 to warn humanity of the dangers of the very war tool they'd built. They debuted the Doomsday Clock image in a 1947 edition, setting the time (arbitrarily) to 7 minutes before midnight. This was soon after World War II, and the threat of worldwide nuclear destruction seemed imminent.

Since then, the time has changed 23 times according to various threats to humanity. It is now set at 2 minutes to midnight. 

Here are the events that have affected the Doomsday Clock. 

The clock moved to 3 minutes to midnight in 1949.

In 1949, President Truman told the American people that the Soviet Union had successfully tested their first nuclear device. Even though Soviets denied the allegations, the Nuclear Arms Race began, moving the clock closer to midnight.  

"We do not advise Americans that doomsday is near and that they can expect atomic bombs to start falling on their heads a month or year from now," the Bulletin wrote. "But we think they have reason to be deeply alarmed and to be prepared for grave decisions." 

In 1953, the clock moved the closest it ever would to midnight at 11:58.

In 1953, the United States tested the first hydrogen bomb, which is more powerful than the atom bomb. During the test, the US destroyed an islet in the Pacific Ocean. In response, the Soviets tested their own H-bomb. The clock has never been closer to midnight. 

"The hands of the Clock of Doom have moved again," the Bulletin wrote. "Only a few more swings of the pendulum, and, from Moscow to Chicago, atomic explosions will strike midnight for Western civilization."

The clock got pushed back to 7 minutes to midnight in 1960 as tensions between the US and the Soviets lessened.

In 1960, the Bulletin called it the "Dawn of a New Decade," as the race to nuclear war slowed down. The Bulletin mentioned a few specific incidents that pointed to the US and the Soviets no longer gearing toward mutual destruction. It highlighted their abilities to avoid confrontation and order a cease-fire at the Suez Canal in 1956 in its assessment.

"We want to express in this move our belief that a new cohesive force has entered the interplay of forces shaping the fate of mankind, and is making the future of man a little less foreboding," the Bulletin wrote about pushing the time back.