Final answer:
The North Star, or Polaris, is used primarily for navigation by indicating true north. It is located using constellations like the Big Dipper and its altitude correlates with the observer's latitude, aiding in determining location before precise clocks and sextants were available.
Step-by-step explanation:
The purpose of the North Star, also known as Polaris, is primarily for navigation. Before the advent of modern navigation tools, sailors and travelers used Polaris to find their way because it remains nearly stationary in the sky, indicating true north. This proved particularly useful because other stars appear to move across the night sky, whereas Polaris' position aligns closely with the north celestial pole, which is the point in the sky that Earth's axis points toward in the Northern Hemisphere.
To locate Polaris in the sky, one can use the 'Big Dipper' constellation as a reference. By extending a line from the two stars at the end of the 'dipper' portion, called 'the guides', you can find Polaris, which lies at a distance approximately five times that between these two stars. This technique has historical significance and is depicted on the flag of Alaska, demonstrating the North Star's enduring role in navigation throughout history.