Ole Rømer
Danish astronomer and instrument maker who invented the modern day thermometer.
International observance days, weeks, and months for September 25, 2026. Plus historical events and birthdays.

September 25, 2026 celebrates World Pharmacist Day, plus 3 more. Every year on September 25th, pharmacists around the globe celebrate World Pharmacist Day. This day focuses on the role pharmacists play in improving health on a global scale.
Read the full story →Every year on the last Friday in September, Save the Koala Day raises awareness for the plight of the koala. It’s also a day to educate the public on the importance of conserving the koala’s natural habitat.
Read the full story →Each year on September 25th World Dream Day encourages individuals, families, and communities around the world to make their dreams a reality. It’s also a day to activate ideas and declare new possibilities.
Read the full story →Every year on September 25th, International Ataxia Awareness Day sheds light on this rare disease. The day also inspires Ataxia organizations and individuals around the world to support action towards a cure.
Read the full story →People born on September 25
Danish astronomer and instrument maker who invented the modern day thermometer.
Architect who is considered the "Father of the Skyscraper." He built the first skyscraper in 1884--the Insurance Building in Chicago, Illinois.
Biologist, geneticist, and embryologist who won the Nobel Prize in Physiology or Medicine in 1993 for discoveries of the roles chromosomes play in heredity.
Co-founder of Russell Stover Candies.
American tennis player who won the U.S. National Championships at the age of 17. In 1905, she became the first American woman to win the Wimbledon singles title. She was the first women and win two separate grand slams in the history of tennis.
Events that occurred on September 25 throughout history
The 12th Amendment is established, creating a procedure for electing the President and Vice President of the U.S.
Charles Follis becomes first American Black to play professional football on an integrated team. He signed a professional contract with the Shelby Blues of the Ohio League and played until injuries caused him to retire.
Henry Ford announces an 8 hour work day, 5 days a week at Ford Motor Company. Ford Ford believed that well-rested, well-paid workers with more leisure time would buy more goods.
Dr. Frank Jobe performs first ulnar collateral ligament replacement surgery on MLB player Tommy John. The successful surgery allowed Tommy John to return to pitch in the majors by 1976. John went on to win 164 more games over 14 additional seasons.