Science
11th International Botanical Congress
On August 23, 1969, the US Post Office issued a set of four stamps for the 11th International Botanical Congress (IBC).
Birth of Gerty Cori
Biochemist Gerty Theresa Radnitz Cori was born on August 15, 1896, in Prague, Austro-Hungarian Empire.
Limited Nuclear Test Ban Treaty Signed
On August 5, 1963, the US, the UK, and the Soviet Union signed the Limited Nuclear Test Ban Treaty.
First International Polar Year
On August 1, 1882, the first International Polar Year (IPY) began.
First Heat-Sensitive Stamp
On June 20, 2017, the USPS issued the first-ever heat sensitive stamp, honoring the total solar eclipse that occurred later that year.
American Scientists Series
On May 4, 2005, the USPS issued the first set of stamps in the American Scientists Series.
The Peace Rose
On April 29, 1945, the Peace rose was made available for sale in the US.
Launch of Pioneer 11
On April 5, 1973 (some sources cite April 6 UTC (Coordinated Universal Time), the Pioneer 11 space probe launched from Cape Canaveral, Florida.
Birth of Luther Burbank
Agricultural science pioneer Luther A. Burbank was born on March 7, 1849, in Lancaster, Massachusetts.