where is this college located?
The university is in Cambridge, Massachusetts.
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts.
how do you know if a star is main sequence By the color-magnitude plots of stellar color versus brightness. how is it formed? After condensation and ignition of a star, it generates thermal energy in its dense core region through nuclear fusion of hydrogen into helium. are they categorized? Yes, the  spectra of stars showed distinctive features, which allowed them to be categorized. how is it done? Through the Harvard Classification Scheme. where was this developed? At Harvard College Observatory
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Harvard University [SEP] Introduction
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Established in 1636 and named for its first benefactor, clergyman John Harvard, Harvard is the oldest institution of higher learning in the United States and among the most prestigious in the world. The Massachusetts colonial legislature, the General Court, authorized Harvard's founding. In its early years, Harvard College primarily trained Congregational and Unitarian clergy, although it has never been formally affiliated with any denomination. Its curriculum and student body were gradually secularized during the 18th century, and by the 19th century, Harvard had emerged as the central cultural establishment among Boston elites.