The Compass Rose

The first activity that Elementary students should probably perform within the subject of Astronomy is to become familiar with how we name terrestrial and celestial directions. How can we give names to which way we are looking or pointing? We start by finding certain special directions, certain special events that always happen in the same direction, every day, no matter where you are. Students should notice that the sun always rises in the same direction–on that side of the house or over that hill. We name this direction where the sun always rises with a word that can be traced back to Greek and Latin words for “dawn”. Students should likewise notice that the sun goes down over there, in that direction, opposite to East, every day, no matter where you are. Our name for the direction where the sun always sets relates to the Latin “vesper”, evening. In between morning and evening, the sun does not go directly overhead, but always passes through the sky high to one side. (I’m assuming here that you are in the mid-northern latitudes. If you want to trace the exact path of the sun, this would be a good time to use a sundial–perhaps a pencil stuck vertically into a spool and set upon a piece of paper on which you trace the shadows, or a pole on the playground with shadows traced with sidewalk chalk.) Our name for the direction of the sun at mid-day has roots that are a bit more obscure, but it is probably related to the word “sun”. There isn’t anything particularly special about the direction opposite to the sunny direction…at least not during the day. If you wait until after the sun goes down, however, you can find one certain particular star, the one halfway between Cassiopeia and the Big Dipper, in that direction, always, regardless of the time of night or the month of the year. This direction, of course, is “north”, and the star is Polaris, or the North Star. (I have no idea where the word “north” comes from.)

Once you give names to these four special sun-given “cardinal” directions, what if you want to be more precise, and name a direction that isn’t exactly one of these four? What’s the direction of that tree between East and South? You make a compound name from the two cardinal directions on either side, of course. Should we say eastsouth or southeast? Just so everybody does it the same way, we agree to always name North or South first, followed by East or West: Northwest, Southeast, etc. What if we want even more precision? What about something between North and Northwest? You can compound the names a second time: North by Northwest. (This time we agree to always name the cardinal direction first.)

Now that we can name any direction we want, it might be useful if we drew on the ground a whole set of arrows pointing in all directions, showing the names for every way all in one pretty picture. If we do this, we have a Compass Rose, something like this:

It is a fun and useful activity for students to color and label their own compass rose, which you can do using the blank template in this Compass Rose Template file that I made.

What if we are sailing a boat or flying an airplane and we need to be able to name any and all directions, conveniently and precisely? Junior High students with some mathematical sophistication may appreciate the method navigators use for this: we name the direction by saying the number of degrees clockwise from North. We call this direction, named as an angle in degrees, the “heading”. Something that is approaching you on a heading of 90 degrees, for example, is directly to the East of you. There is a compass rose containing numerical compass headings in my Compass Roses.

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