Used to be thought that 150 times as big as our sun was the limit. But a star has been found in the Tarantula nebula, which is 265 times bigger, and must have been at least 300 times bigger to begin with. Not surprisingly, it is also the most luminous star ever found, close to ten million times that of the Sun. It is found in a young star cluster containing approx 100 000 stars; but just four massive stars, including this one, produce nearly half of the solar wind and radiation in the entire cluster. [Source: ESO]