can you tell me more about this place?
It is the fifth most populous city in the state.
Cambridge, Massachusetts
it was the fifth most populous city in the state, behind Boston, Worcester, Springfield, and Lowell.
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 where is this college located? The university is in Cambridge, Massachusetts.
wiki:1610798
Cambridge, Massachusetts [SEP] Introduction
Cambridge ( ) is a city in Middlesex County, Massachusetts, and part of the Boston metropolitan area as a major suburb of Boston. , it was the fifth most populous city in the state, behind Boston, Worcester, Springfield, and Lowell. According to the 2010 Census, the city's population was 105,162. It is one of two de jure county seats of Middlesex County, although the county's government was abolished in 1997. Situated directly north of Boston, across the Charles River, it was named in honor of the University of Cambridge in England, once also an important center of the Puritan theology embraced by the town's founders.