Quick Answer
The Big Dipper can be used for celestial navigation by locating the North Star (Polaris) and using it as a reference point to determine direction and latitude. This is achieved by aligning the two stars at the end of the Big Dipper's "bowl" with the North Star. The North Star is almost aligned with the Earth's axis.
Locating the North Star
To locate the North Star, first find the Big Dipper constellation in the night sky. The two stars at the end of the “bowl” are called Dubhe and Merak. These two stars are aligned almost due north and are about 28 degrees apart. To locate the North Star, draw an imaginary line through Dubhe and Merak and extend it about 30 degrees (a little less than the width of your fist held at arm’s length) towards the north. The North Star (Polaris) will be located at the end of this line.
Determining Direction
Once you have located the North Star, you can determine direction by aligning it with the horizon. If the North Star is above the horizon, then the direction of north is directly below it. If the North Star is below the horizon, then the direction of north is directly above it. This method can also be used to determine direction when the sun is not visible, such as at night or during periods of heavy cloud cover.
Estimating Latitude
The North Star can also be used to estimate latitude. The altitude of the North Star above the horizon is approximately equal to the observer’s latitude. For example, if the North Star is at an altitude of 30 degrees above the horizon, then the observer’s latitude is approximately 30 degrees north of the equator. This method can be used to estimate latitude when a map or other navigation tools are not available.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.