Spectral types

Spectral types classify stars based on their light spectra, which reveal their temperature and characteristics. They use letters (O, B, A, F, G, K, M) arranged from the hottest (O, blue) to the coolest (M, red). Each letter has subclasses numbered 0 through 9 for finer detail. For example, the Sun is a G2 star. These types help astronomers understand a star's temperature, size, and color, providing a standardized way to categorize the vast diversity of stars in the universe.