The "Theta system" is located in the heart of the Great Nebula in Orion and is one of the most famous multiple stars in the entire sky. Its four stars, ranging in brightness from 5th magnitude to 8th magnitude, form a quadrilateral called the Trapezium. Several 11th magnitude stars inside and around the quadrilateral undoubtedly belong physically to the Trapezium system. What's more, within a 5' area of the Trapezium, over 400 very faint stars are hidden, extremely young objects recently born from massive clouds of gas and dust. The stars of the Trapezium are exceptionally young, approximately 30,000 years old.