At 5:29 AM on July 16, 1945, in a remote corner of the New Mexico desert, the world changed forever. The first atomic bomb - nicknamed 'Gadget' - detonated at the Trinity test site, releasing energy equivalent to 21,000 tons of TNT. The flash was visible 250 miles away. The mushroom cloud rose 40,000 feet. The sand beneath the tower fused into a green, glassy substance later named 'trinitite.' J. Robert Oppenheimer, watching from a bunker, recalled words from Hindu scripture: 'Now I am become Death, the destroyer of worlds.' Three weeks later, atomic bombs would destroy Hiroshima and Nagasaki. The nuclear age had begun.
The Manhattan Project had been racing against time since 1942. Scientists from across the Allied world gathered in secret facilities to develop the atomic bomb before Nazi Germany could. Los Alamos, New Mexico, was the project's brain - a hidden city where physicists worked to unlock the atom's power.
By summer 1945, they were ready to test their creation. A test site was chosen in the Jornada del Muerto - the 'Journey of the Dead' - a remote desert basin. The test was code-named Trinity, a name chosen by Oppenheimer, possibly from a John Donne poem.
The bomb tested at Trinity was an implosion device using plutonium - a design so complex that scientists weren't certain it would work. Conventional explosives, precisely arranged, would compress a plutonium core to critical mass. The timing had to be perfect; the slightest error would produce a fizzle instead of a bang.
The device was assembled at a ranch house near the test site, then hoisted to the top of a 100-foot steel tower. On the night of July 15, scientists gathered in bunkers and observation points miles away. Rain delayed the test. At 5:29:45 AM, the countdown reached zero.
For a fraction of a second, the desert was brighter than the sun. A woman in Albuquerque, 150 miles away, thought she'd seen a distant lightning flash. A blind woman in the same town later claimed she'd seen the light - the only light she ever perceived. The flash was visible in three states.
The fireball vaporized the steel tower and everything near it. A mushroom cloud, initially purple then turning gray, rose 40,000 feet. The shock wave broke windows 100 miles away. At the base camp, the ground rolled like ocean waves. Scientists who had built the bomb watched in awe and horror at what they had created.
The blast's heat fused the desert sand into a greenish, glassy substance. Scientists named it 'trinitite.' The crater was shallow - about 5 feet deep and 1,100 feet wide - but the glassy coating was unique. Trinitite is mildly radioactive and was once sold as souvenirs until collection was banned.
The crater has been filled in and the trinitite mostly removed, but small pieces remain scattered across the site. A stone obelisk now marks ground zero. The glass that formed at the dawn of the nuclear age is the physical remnant of humanity's most dangerous achievement.
Three weeks after Trinity, atomic bombs destroyed Hiroshima and Nagasaki, killing over 100,000 people instantly and many more from radiation. Japan surrendered. The war ended. The nuclear arms race began.
Trinity Site is now a National Historic Landmark, open to the public twice yearly. The 100-foot tower is gone; only a few structural fragments remain. The ranch house where the bomb was assembled still stands. Visitors can touch the obelisk at ground zero and walk where the nuclear age began. The desert has healed, but the world has never been the same.
Trinity Site (33.68N, 106.47W) lies within White Sands Missile Range in south-central New Mexico. The nearest civilian airport is Albuquerque International (KABQ), 200km north. The site is on an active military range and open only twice yearly. The terrain is flat desert basin. Ground zero is marked by an obelisk and enclosed area. Weather is high desert - hot summers, cold winters, low humidity.