Saksham Azad Quasi-Star | Black Hole Star Black hole inside a star? This is a story of extremes. This is a fascinating story about celestial objects known as quasi-stars, which are much larger than any other known stars, including the red supergiant UY Scuti. With a radius of 1,700 times that of the sun, UY Scuti is a stunning red orb that would extend beyond the boundaries of our Solar System. However, quasi-stars are even more extreme, reaching sizes up to 7,000 times larger than the sun, with diameters extending well into the billions of miles. While their size is impressive, the real difference between quasi-stars and regular stars lies in their energy source. Quasi-stars use an extreme process at their cores, different from the fusion that powers ordinary stars like the sun. They contain at their cores wolfish black holes that feed on incoming matter, in turn giving off radiation to power the star. These black holes grow rapidly. Soon they balloon to