Muammar Muhammad Abu Minyar al-Gaddafi (Arabic: معمر محمد أبو منيار القذافي‎ Arabic pronunciation: [muʕamar al.qaðaːfiː]; /ˈmoʊ.əmɑːr ɡəˈdɑːfi/;  audio (help·info); c. 1942 – 20 October 2011), commonly known as Colonel Gaddafi,[b] was a Libyan revolutionary, politician, and political theorist. He governed Libya as Revolutionary Chairman of the Libyan Arab Republic from 1969 to 1977 and then as the "Brotherly Leader" of the Great Socialist People's Libyan Arab Jamahiriya from 1977 to 2011. Initially ideologically committed to Arab nationalism and Arab socialism, he came to rule according to his own Third International Theory before embracing Pan-Africanism and serving as Chairperson of the African Union from 2009 to 2010.
What was Colonel Gaddafi's date of death? (If the question is unanswerable, say "unanswerable")
20 October 2011