"In a certain sense I made a living for five or six years out of that one star [υ Sagittarii] and it is still a fascinating, not understood, star. It's the first star in which you could clearly demonstrate an enormous difference in chemical composition from the sun. It had almost no hydrogen. It was made largely of helium, and had much too much nitrogen and neon. It's still a mystery in many ways ... But it was the first star ever analysed that had a different composition, and I started that area of spectroscopy in the late thirties."