https://mike-naylor.blogspot.com/2012/07/extra-second-and-celebrating-gigasecond.html
Mike Naylor - creative mathematics: Extra second, and celebrating a gigasecond
Last night an extra second was added to world time. It happened at 23:59:60 UTC, or Universal Time which is the same as Greenwich Mean Time ...
mike naylorcreative mathematicsextrasecondcelebrating