Polaris--the Polar Star--our North Star--was the guiding light of the Pilgrim world. It did not rotate with the other stars but held steady at the core of their universe while the others circled it. Centering on this star in the northern sky opened a sweeping perspective of the heavens.There's no question that astronomy was a fundamental source of knowledge that bolstered their religious beliefs. http://vimeo.com/4330429. The Pilgrims were men of the New Testament taking their script from the Old. They held monotheism as sacred-- the belief in one God reigning supreme. Polaris fit the part perfectly. Adventurers of the enlightenment had their "lonestar."
The Pilgrims knew when they observed a magnetic compass that the needle pointed to a place in the sky slightly west of their alignment with the North Star. Astronomical measurements calculated this "degree of variation" at 13º west longitude in the 1630's. This variation then floated down from 13º west to 6º west by the 1800's but slowly rose again to 17º by the 1970's. The degree of variation on Cape Cod has now crested and is on its way down now ranging near 15º.
Geologists think that the change in variation is related to the shifting in the molten core in the earth. The theory is that a mass of iron near the North Pole is rotating and causing this shift in variation in a cycle of about 400 years. The Pilgrims would have relied on 13º west longitude for their compass readings as evidence by the first land survey of Cape Cod undertaken in the mid-1630's.