India is developing satellites to study stars, including the Sun, a top space official has said. "The satellite, Astrosat, which will study stars, will be unique in three aspects -- UV rays, visible and X-rays. Even Hubble (Space Telescope) does not have this aspect. Though Hubble is big, Astrosat will be a small one," the director of Space Applications Center at the state-owned Indian Space Research Organization, A.S. Kiran Kumar, told the media late Friday evening. Astrosat, whose diameter would be 300 mm as against Hubble's 2. 4 meter, is likely to be launched next year, he said. Kumar said that work was in progress to develop another satellite, Aditya, to study the Sun. "Its launch may take three to four years," he added. India has so far successfully launched over 100 satellites into space since 1975.