Astronomers studied I Zw 36 (≈Z⊙/14) using the Hubble Space Telescope. Before that, they took pictures using ultraviolet light using the pre-COST Faint Object Camera (FOC) and Near Infrared Camera and Multi-Object Spectrometer (NICMOS). FOC seemed to show that I Zw 36 had large, hot stars but NICMOS said it had cold stars that were small or medium sized. Some evidence shows the stars were active and then the galaxy became compact and blue. The evidence of luminous and asymptotic branches of stars suggests they formed several million years ago. The giant red branches of the galaxy may have at least 1-2 billion years.