November 13, 2017

Star Navigation: Tips for Exploring Sans Technology

Whether you’re in the Northern or Southern Hemisphere, this guide will help you orient yourself at night by using the stars.

navigation by stars

Before modern technology allowed navigation via GPS or compass, people devised different methods to figure out which direction they were traveling — including using the stars. Today, celestial navigation can be helpful if technology fails on a backpacking trip, but it can also be an enriching way to connect more with your environment. If you’re camping under a dark sky, it can be exciting to stargaze and share your knowledge of star navigation with friends.

How you figure out directions using the stars depends on which hemisphere you’re in, as different stars are visible in the Northern Hemisphere than in the Southern. This guide has navigation tips for both hemispheres, so you can learn to orient yourself at night no matter where you are.

Navigating by stars in the Northern Hemisphere

Use these tips to find your way at night if you’re north of the equator.

Finding true north via the North Star

The North Star, otherwise known as Polaris, is unique, as it sits almost directly above the North Pole. According to NASA, it’s only offset from the North Celestial Pole by .7 degrees. Follow an imaginary line from the North Star down to the horizon and you’ve found true north.

There are a few ways to locate the North Star. On a dark and clear night, look for the Little Dipper, which is a part of the Ursa Minor constellation. Polaris is the last star on the handle of the Little Dipper. That might sound easy, but the Little Dipper is often faint because of city lights and is hard to find because it’s small.

Many people use the Big Dipper as a guide to finding the North Star, because this asterism (noticeable pattern of stars) is much bigger and brighter than the Little Dipper. The Big Dipper is also known as the Plough or the Saucepan because of its shape, and it’s part of the Ursa Major constellation. Here’s how to find Polaris using the Big Dipper:

  • Find the “pointer stars,” which are the two stars farthest away from the handle of the Big Dipper that form the edge of the bowl.
  • Draw an imaginary line between the pointers. Extend the straight line in the direction opposite of that which the handle of the Big Dipper curves.
  • The North Star will be the next bright star you find along that line, approximately five times the distance between the two pointer stars away.
  • Polaris is about halfway between The Big Dipper and Cassiopeia, a “W” shaped constellation in the Northern Hemisphere that’s also known as the Queen. If you hit Cassiopeia, you’ve gone too far.

At the equator, the North Star sits on the horizon. After you cross the equator into the Southern Hemisphere, Polaris is no longer visible.

Finding south, east, and west

Polaris is an incredibly useful star to find any direction. The most accurate way to find south in the Northern Hemisphere is to use the North Star to find north and simply head in the opposite direction. If you are facing north, west is always on your left and east is always on your right.

You can also use the moon for a less accurate albeit interesting method to approximate south. If there’s a crescent moon high in the sky, draw an imaginary line connecting the tips of the crescent and continuing down to the horizon. That point is roughly south. This can be helpful on a cloudy night when stars are obscured but the crescent moon is visible.

Like the sun, the famous constellation Orion rises in the east and sets in the west. This constellation can be seen anywhere in the world, but is most visible in the Northern Hemisphere during winter and the Southern Hemisphere during summer. You can easily recognize Orion the Hunter by its “belt” of three bright stars.

Navigating by stars in the Southern Hemisphere

Learn how to orient yourself south of the equator with these tips.

Finding due south via the Southern Cross

Finding south in the Southern Hemisphere is trickier than finding north in the Northern Hemisphere, since the Southern Hemisphere doesn’t have a single bright guiding star. Technically, there is a star called Sigma Octantis that sits above the South Pole, but it’s 25 times dimmer than Polaris, so it’s too faint to be relied upon for navigation.

In the Southern Hemisphere, the Southern Cross points the way south. The Southern Cross is a constellation also known as Crux, and its brightest star Acrux is the thirteenth-brightest star visible from Earth. Many people think the Southern Cross also resembles a kite due to its fifth star giving it a diamond shape.

There are a couple of ways to use the Southern Cross to find south:

Using only the Southern Cross:

  • Draw an imaginary line between the stars making up the long axis of the cross (Acrux and Gacrux).
  • Extend the line through the “bottom” of the cross 4.5 more cross lengths.
  • From where this line ends, drop your eyes down to the horizon and that is approximately south.

Using the Southern Cross and Pointer Stars:

  • Locate two bright neighboring stars, Alpha Centauri and Beta Centauri, called the “pointer stars” because they point to the top of the cross.
  • Draw an imaginary line connecting these stars. Halfway through this line, draw another imaginary line perpendicular to it that extends far out.
  • Draw an imaginary line through the long axis of the Southern Cross, extending the line through the bottom.
  • Find where these two imaginary lines from the pointer stars and the Southern Cross intersect. From that location, drop your eyes down to the horizon and that is approximately south.

 

Depending on the time of year, the cross may be pointing upright, sideways, or upside down.

Finding north, east, and west

Just as you can use Polaris to find north and then all other directions, use the Southern Cross to find south first. If you are facing south, west is on your right, east is on your left, and north is behind you.

If you’re in the Southern Hemisphere, the crescent moon method (see above) will help you approximate north.

Practice makes perfect

Stargazing and learning about the cosmos can be an inspiring activity, but knowing how to navigate using the stars can have a practical purpose if you need to figure out which direction you’re traveling. If you’re on a backpacking trip or hiking at night, this information can really come in handy. Plus, successfully navigating via the stars just takes a bit of time and practice — no expert star knowledge needed.

Try tonight or practice on your next nighttime outing. You might be surprised at how good it feels to put this knowledge in action.

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