All throughout the universe,there are stars in varying phases and ages. The oldest detected Kepler planets (exoplanets found using NASA's Kepler telescope) are approximately 11 billion years primitive, and the planetary diversity suggests that around other stars, and such initially frozen worlds could be the size of Earth and could even provide habitable conditions once the star becomes older. Astronomers usually looked at middle-aged stars like our sun,but to find habitable worlds, one needs to observe around stars of all ages.
Source: phys.org