# A Brief History of Unix Time

January 1, 1970
Unix Epoch

This is the day the Unix clock began (or December 31, 1969 if you live behind UTC 😉).

October 17, 1973
Digits Within ISO 8601 Format

At 6:36:57 PM UTC, the date in ISO 8601 format (1973-10-17) within the time digits (119731017) appeared for the first time.

September 9, 2001
1 Billion Seconds

Unix time reached 1,000,000,000 seconds at 1:46:40 AM UTC. The Danish UNIX User Group celebrated this in Copenhagen, Denmark.

February 13, 2009
1,234,567,890 Seconds

At 11:31:30 PM UTC, the digits of the time were 1234567890. This was celebrated worldwide, and even Google had a doodle for it.

May 18, 2033
2 Billion Seconds

Unix time will reach 2,000,000,000 seconds at 3:33:20 AM UTC.

January 19, 2038
Unix Epochalypse

Also known as the year 2038 problem, clocks running on a 32-bit signed integer will flip from 3:14:08 AM UTC on this day to 8:45:52 PM UTC on December 13, 1901. Therefore, values only from -2,147,483,648 to 2,147,483,647 for the second are supported.