This article is part of a series that will delve into the history of the Trinity Site Test, which marked its 80th anniversary on July 16, 2025, and the commemoration of the growth and evolution of White Sands Missile Range, which marked its 80th anniversary on July 9, 2025. A commemoration of the establishment of White Sands Proving Ground, now called White Sands Missile Range, will take place on Oct. 17 at WSMR and an observance for the test at Trinity Site will take place on Oct. 18 at the Trinity Site Open House.

The test was scheduled for 4 a.m. July 16, 1945, but was postponed due to early morning rain and lightning. The device could not be tested under these conditions because rain and wind would increase the danger from radioactive fallout and interfere with observation of the test which was conducted to see if the device would work and to measure its yield.

At 4:45 a.m. the crucial weather report came through announcing “calm to light winds with broken clouds” for the following two hours. At 5:10 a.m. the countdown started; at 5:29:45 a.m. Mountain War Time, the device was ignited.

To observers, the brilliance of the light, watched through dark glasses, overshadowed the shock wave and loud boom that arrived soon after. Many witnesses remembered the sound bounding off the mountains which created an echoing effect.

Hans Bethe, one of the contributing scientists, wrote “it looked like a giant magnesium flare which kept on for what seemed a whole minute but was actually one or two seconds. The white ball grew and after a few seconds became clouded with dust whipped up by the blast from the ground and rose and left behind a black trail of dust particles.”

Joe McKibben, another scientist, said, “We had a lot of flood lights on for taking movies of the control panel. When the device went off, the lights were drowned out by the big light coming in through the open door in the back.”

Others were impressed by the heat they immediately felt. Military policeman Davis said, “The heat was like opening up an oven door, even at 10 miles.”

Dr. Phillip Morrison said, “Suddenly, not only was there a bright light but where we were, 10 miles away, there was the heat of the sun on our faces…Then, only minutes later, the real sun rose and again you felt the same heat to the face from the sunrise. So, we saw two sunrises.”

Visitors sometimes ask about soldiers watching the test from trenches, but that took place later during subsequent tests in Nevada, not at Trinity Site. Personnel at Trinity were in bunkers at least 10,000 yards from ground zero.

Some people who didn’t get invited took it upon themselves to find a viewing spot. In his book “Trinity” Jim Eckles tells the story of Harold Argo who described himself as a junior guy “who punched a calculator.” He wanted to see the test, so he studied topographic maps of the area and selected Chupadera Peak, just south of Socorro and west of the highway. He said he could see the site with binoculars but was too far away to hear the loudspeaker announcements. He didn’t realize the shot was delayed because of weather. At 5:25 a.m. he decided to leave. He threw his blanket over his shoulder, took 10 steps down the hill, and suddenly everything lit up. At that moment history was made, and the world was ushered into the nuclear age.