Einsteinium was discovered in the debris of the first hydrogen bomb test, "Trinity", conducted on July 16, 1945, in the Jornada del Muerto desert in New Mexico, USA.

The discovery team was led by Albert Ghiorso, a chemist at the University of California, Berkeley, and included Glenn Seaborg, Stanley G. Thompson, Kenneth Street Jr., and others.

It's important to note that while they discovered einsteinium, they did not isolate it until 1952.