The winter solstice alignment at Newgrange, Ireland is a phenomenon that occurs once a year. On the morning of the winter solstice, sunlight penetrates into the passage and illuminates the central chamber of the ancient monument for about 17 minutes. This event has been celebrated by people in various cultures for centuries as it marks the longest night and shortest day of the year. The alignment was first discovered by Professor M.J O’Kelly in 1968 and he determined that it had been aligned to this exact moment since its construction over 5000 years ago.