How many types of stars exist?
Grades, from hottest to coldest, with associated colors: O-Blue B-Bluish White A-White F-Whitish Yellow G-Yellowish Orange K-Orange Red M-Red
Oh Be A Fine Girl/Guy Kiss Me
Sun belongs to G, with surface temperature in the range
An improved version is 0 - 9 grading;
Based on the width of absorption lines in the star-spectrum::
I II III IV V. This is also called luminosity classification
Sun is in the spectral class G2V, revealing the codes G 2 V in three types of classification