Answer:
The spectral types and sub-classes represent a temperature sequence, from hotter (O stars) to cooler (M stars), and from hotter (subclass 0) to cooler (subclass 9). The temperature defines the star's "color" and surface brightness. ... Stars are also classified by luminosity class.
Explanation:
The line located at 0° latitude is the equator.
Many observations provide a history that one may be able to surmise theories from.
