In the final years of his life Huygens composed one of the earliest discussions of extraterrestrial life, published after his death as the Cosmotheoros (1698).
Sa huling araw ng kanyang buhay Huygens binubuo ng isa sa mga earliest talakayan ng extraterrestrial buhay, nai-publish na pagkatapos ng kanyang kamatayan bilang ng Cosmotheoros (1698).