Today in History — 2026-08-21

Harry Daghlian

Haroutune Krikor Daghlian Jr. was an American physicist with the Manhattan Project, which designed and produced the atomic bombs that were used in World War II. He accidentally irradiated himself on August 21, 1945, during a critical mass experiment at the remote Omega Site of the Los Alamos Laboratory in New Mexico and died 25 days later from the resultant radiation poisoning.

More on this day

  • 1415: Prince Henry the Navigator Prince Henry the Navigator, was a Portuguese prince, a central figure in the early days of the Portuguese Empire and often credited as one of the main initiators of the Age of Discovery. Henry was the third child of King John I of Portugal, who founded the House of Aviz.
  • 2017: Solar eclipse of August 21, 2017 A total solar eclipse, dubbed the "Great American Eclipse" by some media, occurred on August 21, 2017. It was visible within a band that spanned the contiguous United States from the Pacific to the Atlantic coasts. It was also visible as a partial solar eclipse from as far north as Nunavut in northern Canada to as far south as northern South America. In northwestern Europe and Africa, it was partially visible in the late evening. In northeastern Asia, it was partially visible at sunrise.
  • 1986: Limnic eruption A limnic eruption, also known as a lake overturn, is an extremely rare type of natural hazard in which dissolved carbon dioxide suddenly erupts from deep lake waters, forming a gas cloud capable of asphyxiating wildlife, livestock, and humans. Scientists believe earthquakes, volcanic activity, and other explosive events can serve as triggers for limnic eruptions as the rising CO2 ejects water from the lake. Lakes in which such activity occurs are referred to as limnically active lakes or exploding lakes. Some features of limnically active lakes include:CO2-saturated incoming water A cool lake bottom indicating an absence of direct volcanic heat in the lake waters. An upper and lower thermal layer with differing CO2 saturations Proximity to areas with volcanic activity
  • 1986: Volcano A volcano is a vent or fissure in the crust of a planetary-mass object that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes resulting from divergent tectonic activity are usually non-explosive whereas those resulting from convergent tectonic activity cause violent eruptions. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift, the Wells Gray-Clearwater volcanic field, and the Rio Grande rift in North America. Volcanism away from plate boundaries most likely arises from upwelling diapirs from the core–mantle boundary called mantle plumes, 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism or intraplate volcanism, in which the plume may cause thinning of the crust and result in a volcanic island chain due to the continuous movement of the tectonic plate, of which the Hawaiian hotspot is an example. Volcanoes are usually not created at transform tectonic boundaries where two tectonic plates slide past one another.
  • 1991: Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to the southeast and shares a maritime border with Sweden to the west. Latvia covers an area of 64,573 km2 (24,932 sq mi), with a population of 1.83 million. The country has a temperate seasonal climate. Its capital and largest city is Riga. Latvians, who are the titular nation and comprise 65.5% of the country's population, belong to the ethnolinguistic group of the Balts and speak Latvian. Russians are the most prominent minority in the country, at almost a quarter of the population; 37.7% of the population speak Russian as their native tongue.
  • 1821: Jarvis Island Jarvis Island is an uninhabited 4.5 km2 (1.7 sq mi) coral island located in the South Pacific Ocean, about halfway between Hawaii and the Cook Islands. It is an unincorporated, unorganized territory of the United States, administered by the United States Fish and Wildlife Service of the United States Department of the Interior as part of the National Wildlife Refuge system. Unlike most coral atolls, the lagoon on Jarvis is wholly dry.