Three observation points were established at 10,000 yards from ground
zero. These were wooden shelters protected by concrete and earth.
The south bunker served as the control center for the test. The
automatic firing device was triggered from there as key men such as
Dr. Robert Oppenheimer, head of Los Alamos, watched. None of the
manned bunkers are left.
Many scientists and support personnel, including Gen. Leslie Groves,
head of the Manhattan Project, watched the explosion from base camp
which was ten miles southwest of ground zero. All the buildings at
base camp were removed after the test. Most visiting VIPs watched
from Compania Hill, 20 miles northwest of ground zero.
The test was scheduled for 4 a.m. July 16, but rain and lightning
early that morning caused it to be postponed. The device could not be
exploded under rainy conditions because rain and winds would increase
the danger from radioactive fallout and interfere with observation of
the test. 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 the countdown started and at 5:29:45 the device exploded
successfully. To most observers the brilliance of the light from the
explosion--watched through dark glasses--overshadowed the shock wave
and sound that arrived later.
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 explosion 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 bomb 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."