The Sun doesn't have a perfect blackbody spectrum because its spectrum consists of emission lines fo the elements in the Sun, so there are some gaps. the relatively cool outer layers absorb photons emitted in the hot inner parts of the Sun, producing absorption lines. its core is much hotter than its surface, so the shape of the curve is distorted. the coronal mass ejections interfere with the photons, adding too much noise to the spectrum the Sun is too hot to radiate at all wavelengths