Over the centuries, humans discovered that the Pole Star could serve as a guide to directional north. The ability to find the Pole Star is an excellent survival skill, but it could also be a fun activity on a clear night.
Part 1 of 3: Finding the Dipper
Step 1. Know what to look for
The Big Dipper constitutes a constellation which is also known as "the Dipper" or "the Plow". The two stars at the outer end of the "Dipper" (or the "blade" of the Plow) are known as the "pointers", since they form a straight line pointing towards the Pole Star (see figure).
Step 2. Find the constellation Ursa Major
The Dipper is made up of seven stars that can be recognized very easily in the night sky. These seven stars are shaped like a cup with a handle.
- You can make it easier to locate Ursa Major using a constellation map if you have it at your disposal. It is also possible to download an application to find constellations to your mobile devices (for example, SkyView for Apple devices or SkyMap for Android devices).
- It is also possible to observe the sky on a clear night, since, as there are no clouds, it will be easier for you to find the groupings of stars.
Step 3. Understand that the Dipper changes position in the sky
Because the Big Dipper rotates in the sky, its position depends on when you observe it. It will always revolve around the Pole Star. Therefore, sometimes the mug will face upwards and sometimes it will face downwards or to the side.
- Do not forget that the Dipper is a fixed element of the sky in the northern hemisphere, so you will only be able to observe it and follow these instructions if you are in this hemisphere.
Here are some seasonal guides to finding the Dipper based on its location at midnight:
- In the spring, the Dipper is located north of the Pole Star (or Polaris) and the cup faces downward.
- In the summer, the Dipper is located just west of Polaris and the bowl faces to the right.
- In the fall, the Dipper is located south of Polaris and the cup faces upward.
- In the winter, the Dipper is located east of Polaris and the cup faces to the left.
Part 2 of 3: Finding the Pole Star
Step 1. Know your latitude
This constitutes your position to the north or south of the equator. The height of the Pole Star above the horizon is equal to the latitude of the observer. It will not be possible to observe it if you are at or below the equator. However, for practical purposes, if you are farther south than 10 degrees north latitude, the star will be too close to the horizon to be seen.
Here are some measurements of latitude for some important places in the Northern Hemisphere, for reference:
- The north pole is at 90 degrees north latitude.
- Reykjavik, Iceland, is located at 70 degrees north latitude.
- Juneau, Alaska, and Edinburgh, Scotland, lie at 60 degrees north latitude.
- Seattle, Washington, New York City, and Venice, Italy lie at 50 degrees north latitude.
- Denver, Colorado, and Seoul, South Korea, lie at 40 degrees north latitude.
- New Orleans, Louisiana, and Orlando, Florida, lie at 30 degrees north latitude.
- Mexico City and Kingston, Jamaica, lie at 20 degrees north latitude.
- San José, Costa Rica, Panama City lie at 10 degrees north latitude.
- If you have internet access, you could determine your latitude using an online latitude finder (such as NASA's).
If you don't know your latitude and can't access the internet, you could look at the sun at noon to determine your latitude.
- To do this, place a flat board or stick on the ground so that it points upward and is completely perpendicular to the ground.
- Lay another flat board on top (so that both boards form a T) but lean it toward the sun. Your latitude in degrees will be the angle of the shadow cast by the sun.
- Note that these measurements will only be accurate on March 21 and September 21 (that is, the spring and fall equinoxes). If it is winter (on December 21, specifically), you must subtract 23, 45 degrees from the measure you obtain and, if it is summer (on June 21, specifically), you must add 23, 45. These variations in measurements must be to the way the Earth tilts when orbiting the sun.
- If you know where you are in terms of degrees of latitude, you should look north and look for a moderately bright star that is several degrees above the horizon. If you extend your fist in front of you, this represents about 10 degrees in the sky. You can measure the height above the horizon this way.
Step 2. Locate the Pole Star in the night sky
The two stars at the outer end of the Dipper's "cup" (that is, those furthest from the "handle") are the key to finding the Pole Star.
- Draw an imaginary straight line through these two stars in the direction of Ursa Minor. In this way, you will reach the handle of the Ursa Minor saucepan. The brightest star at the end of this handle will be the Pole Star.
- The Polar Star (Polaris, sometimes Dhruva Tara or "fixed star", Taivaanneula or "needle of the sky" or Lodestar) constitutes a multiple star of second magnitude that is to about 430 years light of the Earth. Its close proximity to the north celestial pole makes it appear to be motionless on the northern horizon.
Step 3. Locate Cassiopeia
The constellation Cassiopeia is always on the opposite side to Ursa Major and has the appearance of a large W. The Pole Star is about halfway between the central star of Cassiopeia and the third star on the handle of the Dipper. This is a useful trick, especially during the fall, as it is then more difficult to find the Dipper.
Part 3 of 3: Using the Pole Star as a Guide
Step 1. Trust the Pole Star
This is a more reliable guide than a compass, since the latter can be affected by environmental factors and periodic variations. In case it is possible to find north through the location of the Pole Star but the compass indicates otherwise, you must follow the direction that the Pole Star indicates.
Step 2. Determine your latitude from the location of the Pole Star in the sky
Your latitude will determine where the Pole Star appears in the sky. If you are at the north pole, it will appear directly above you, while if you are at the equator, it will appear on the horizon in accordance with the latitudes of both places.
You can use the "fist" method and count the number of these at which the Pole Star appears on the horizon in order to obtain your own latitude. Don't forget that each "fist" represents about 10 degrees of latitude
Step 3. Determine where you want to go
You can guide yourself in a certain direction using the Pole Star or, at the very least, use it to avoid circling in case you are lost. Consider your location and the direction that would be most helpful to you, especially if you find yourself lost in nature and need to return to civilization.
- After finding the Pole Star, look towards it to guide you north. Looking in the opposite direction to it will guide you south.
- Extend your arms to your sides when looking at the Pole Star. This way, your left hand will point west and your right hand will point east.