Science & Discovery in the 12th century

14 sourced entries, 1100 CE to 1192 CE, oldest first. Also see Science & Discovery across every century or everything else in the 12th century.

• 1100Checkers is invented (approximate date).source
• 1103Magnus Olafsson (Old Norse: Magnús Óláfsson, Norwegian: Magnus Olavsson; 1073 – 24 August 1103), better known as Magnus Barefoot (Magnús berfœttr)Irelandsource
• 1104Autumn – The volcano Hekla erupts in Iceland and devastates farms for 45 miles (some 70 km) around.source
• 1106February 2 – A comet (the Great Comet of 1106) is seen and reported by several civilisations around the world. Lasting for 40 days, the comet grows steadily in brightness until finally fading away.source
• 1120Walcher of Malvern, an English astronomer and mathematician, creates a system of measurement for the Earth using degrees, minutes and seconds of latitude and longitude.source
• 1124August 11 – A solar eclipse took place over northern Europe, after Sigurd the Crusader, King of Norway, led the Kalmare ledung, a naval attack on Kalmar, in order to Christianize the region of Småland. A historian later noted that Sigurd's crusade happened in the summer before "the great darkness".source
• 1160Earliest recorded reference to Dromcollogher - in the Book of Leinster.Irelandsource
• 1163The Norwegian Law of Succession is introduced.source
• 1172Henry II of England leaves Ireland.Irelandsource
• 1173Algebraic chess notation is first recorded.source
• 1181January – William VIII of Montpellier frees the teaching of medicine from any monopoly in France, an origin of the University of Montpellier.source
• 1181Chinese and Japanese astronomers observe what has come to be understood as supernova SN 1181. One of only eight supernovae in the Milky Way observed in recorded history. It appears in the constellation Cassiopeia and is visible in the night sky for about 185 days. The radio source 3C58 was thought to be the remnant from this event, but opinion is shifting towards the recently discovered nebula Pa 30 (ref : Arxiv 2105.12384).source
• 1185May 1 – The Solar eclipse of 1 May 1185, visible across Central America, Northern and Eastern Europe and Kazakhstan, occurs.source
• 1192January 7 – Venus occults Jupiter.source