"The heaviest and brightest star known to exist—with a mass some 300 times as big as our own Sun—has been discovered by British astronomers." The Independent reports. "Its existence defies current views on the maximum size of stellar objects," says astronomers who discovered the massive star. "It is the biggest of a number of extremely rare 'super heavyweight' stars that form in clusters so dense and bright that until now it has been impossible to distinguish between many of the individual objects. R136a1," as the star is called, "is so bright that it would outshine the Sun by as much as the Sun outshines the Moon—a luminosity close to 10 million times greater than our own star."