As an expert in astrophysics, I can tell you that the concept of "the biggest sun" can be a bit misleading because our Sun is just one of many stars in the universe. However, when we talk about the largest stars in terms of size, we're often referring to the most massive and voluminous ones. The largest known stars are red supergiants, and one of the most notable among them is UY Scuti. This star is a hypergiant with a radius estimated to be about 1,700 times larger than that of our Sun. It's so large that if it were placed at the center of our Solar System, it could extend beyond the orbit of Jupiter.

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Supergiant stars are the largest stars in the universe. They can be thousands of times bigger than our Sun and have a mass up to 100 times greater. The largest known supergiant star, VY Canis Majoris, is up to 2,100 times the size of the Sun (based on upper estimates).read more >>