Comparison of star sizes, computer illustration. This image shows the relative sizes of two typical (main sequence) stars, our Sun and Sirius A, and two supergiant stars. Rigel is a hot, blue B-class star in the constellation of Orion. It is about 60 times the diameter of the Sun with 15 to 20 times the mass, and emits about 70,000 times as much radiation. Antares is an immense red class supergiant in the constellation of Scorpius. It is about 10-15 times the mass of the Sun and emits 40,000 times the radiation. Its diameter is 8 times the distance between the Earth and the Sun. Most supergiant stars will eventually explode as supernovas.