Figure 11-18 Red Giant and Plume Main-sequence stars produce energy in a hydrogen-fusing core that will shrink to about ⅓ of its size when it becomes a red giant, causing hydrogen fusion to take place at a furious rate. The Sun’s luminosity will be about 2000 times greater than today, and the increased luminosity will make the Sun’s outer layers expand to approximately 100 times their present size, swallowing its inner planets and having a hot plume reaching the edge of the solar system.