Perseus double star cluster. Infrared composite image of the double cluster comprising H Persei (NGC 869, centre right) and Chi Persei (NGC 884, centre left). These images were made as part of the Two Micron All Sky Survey (2MASS) project using ground-based telescopes in the USA and in Chile. The project began in 1997 with the aim of surveying the entire sky using near-infrared technology. Infrared can peer through the dense dust that obscures millions of stars from sight at visible wavelengths. Data from the 2MASS project and from optical photometry have dated the star clusters to 12.6 million years old. They are 7300 light years from Earth.