Cardinal Directions for Casual Stargazers

Compass Rose, Brosen, April 13, 2006. Retrieved from Wikipedia by Jim Johnson on January 19, 2015.
Compass Rose, Brosen, April 13, 2006. Retrieved from Wikipedia by Jim Johnson on January 19, 2015.

Being able to identify the four cardinal directions – north, south, east, and west – is necessary so that stargazers can correctly orient a star chart to permit a desired constellation might be found. Close is good enough for our purpose, and once any one of the cardinal directions is determined, the other three are easily derived by imagining our body as a compass rose. I will describe a compass rose stance and how to use it, and I will present three easy methods to determine at least one cardinal direction. Many more methods can be found by a Web search on “finding cardinal directions without a compass.”

Assume a compass rose stance by standing up, and extending the arms up and straight out from the sides, and horizontal to the ground. Assume that you already know which way is north and that you are facing in that direction. Looking at the compass rose above, we can see that the face is the north point of the rose, the right hand is east, the left is west, and the south point is the back of the head. If we can determine any one of the four cardinal directions, and turn our self until the correct point of the compass rose stance is aligned in that direction, then we can determine the other three cardinal directions off of the the other three points of our compass rose stance.

The easiest method to find one cardinal direction is based on the Sun, and can be used if one knows where the Sun rises and sets. The Sun rises in the east, and it sets in the west. That orange glow on the horizon before sunrise and after sunset also indicates which directions are east and west, respectively. To illustrate, if I am observing in the early evening and can still see the sunset orange glow is brightest at one point on the horizon, I have determined which direction is west. Assuming my compass rose stance with my left hand pointing toward the west, I know that north is straight ahead, east is to my left, and south is behind me.

A compass is just as easy as working of off the sunrise and sunset points if one is available. Since the red arrow will always point north, an observer can face in direction of the red arrow and derive the other three directions by extending the hands toward the horizon. The left hand points west and the right hand points east. South, of course, is behind the observer.

Once north has been determined, it is easier to find Polaris, which can be used in the middle of the night from any location. Read Polaris, The North Star to learn how to find this star and use it to determine which direction is north. I recommend that any serious stargazer invest the time in learning this method.

One of these processes or a similar process must be used to determine the cardinal directions the first time that a stargazer observes from a new location. If a stargazer is to make repeated observations from the same point, then the cardinal directions need only be determined once and committed to memory or noted in an observing log. For instance if an observer remembers that a distinct tree on the distant horizon that is just a little left of North, then using that tree as a future reference, the observer readily knows which direction is north on subsequent visits to that spot.

Knowing the cardinal directions is an inherent part of observing the sky. Learning how to determine these directions is quite easy, and becomes second nature with just a little practice, and after a while the compass rose stance will no longer be needed.

© James R. Johnson, 2015.
jim@jrjohnson.net

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