Queen Margrethe II of Denmark is hosting a private dinner at Amalienborg to celebrate Prince Joachim's 50th birthday, with family and friends. Prince Joachim Holger Waldemar Christian was born at 4.30 am on 7 June 1969 at the Rigshospitalet in Copenhagen, weighing in at 3.520 kg (7 pounds and 12 ounces) and 52 cm (about…