HE 1523-0901 is the oldest known star in the milky way galaxy. It is also known as Methuselah star. It is the metal-poor subgiant star about 190 light years away from the Earth in the constellation Libra. The age of the star is a constant factor which is 14.46 ± 0.8. Gyr. The apparent magnitude of the star is 7.223. The star is one of the closest Population II stars to us.