Wikipedia:Selected anniversaries/January 1
- 1801 - Giuseppe Piazzi discovered the first asteroid, 1 Ceres.
- 1801 - The Kingdom of Ireland merged with the Kingdom of Great Britain, adding St. Patrick's saltire to the Union Jack.
- 1959 - President Fulgencio Batista of Cuba fled to the Dominican Republic as forces under Fidel Castro took control of Havana.
- 1983 - The ARPANET changed its core networking protocols from NCP to TCP/IP, marking the beginning of the Internet as we know it today.
- 1995 - The World Trade Organization was created to replace the General Agreement on Tariffs and Trade.
Recent days: December 31 - December 30 - December 29