- 5 September 1977 – The space probe Voyager 1 (pictured), now the farthest man-made object from Earth, is launched
- 17 September 1991 – The Linux kernel, the operating system kernel used by the GNU/Linux family of Unix-like operating systems, is first released
- 24 September 1996 – Representatives of 71 nations sign the Comprehensive Nuclear-Test-Ban Treaty at the United Nations
- 29 September 1954 – The European Organization for Nuclear Research (CERN), the scientific organization that operates the Large Hadron Collider, is founded