Finding the North Star and Using It to Navigate

Why Polaris Is Worth Knowing

Of the thousands of stars visible from a British back garden, one barely seems to move. Polaris, the North Star, sits less than a degree from the north celestial pole, which means the entire sky wheels slowly around it while it stays almost perfectly still. From anywhere in the UK it never sets, never dips below the horizon, and never fails you on a clear night. That single fact makes it the most useful star in the sky: a compass, a latitude marker and the anchor point for every star chart you will ever use.

It is worth saying what Polaris is not. It is not the brightest star in the sky — that honour belongs to Sirius, and the planets Venus and Jupiter easily outshine it. Polaris is a modest second-magnitude star, roughly the same brightness as the stars of the Plough. It is unremarkable in appearance and extraordinary in position, and that is exactly why beginners should learn it first.

Finding Polaris from the Plough

The Plough, the familiar seven-star pattern in Ursa Major, is your signpost. Four stars form its bowl and three its handle, and the two stars at the outer edge of the bowl — the ones furthest from the handle, named Dubhe and Merak — are the famous pointers. Draw an imaginary line from Merak through Dubhe, continuing away from the handle, and extend it about five times the distance between those two stars. That line lands you on Polaris.

• Check the shape: the Plough sometimes hangs upside down or stands on its handle, because it swings around Polaris through the night and the year.
• Don't be fooled: Polaris is the end of the Little Bear's tail, and the small, faint bowl of the Little Dipper hangs from it back towards the Plough.
• Timing matters: the Plough is circumpolar from Britain, so it never sets, but on autumn evenings it sits low in the north and may hide behind houses or trees. Look again an hour or two later.

Cassiopeia: The Backup Route

When the Plough is low or obscured, turn to Cassiopeia, the bright W-shaped constellation on the opposite side of Polaris. The two are partners: as the sky rotates, one rises while the other sinks, so if one is awkward, the other is usually well placed.

To find Polaris from Cassiopeia, use the fact that the North Star lies roughly midway between the two constellations, on the far side of the Plough from Cassiopeia. Trace the W, follow the general direction its shape opens out towards, and look for a solitary star of similar brightness to the W's stars, sitting in a comparatively empty patch of sky. That emptiness is a useful clue in itself — Polaris has no bright neighbours, which is why it stands out once you know where to look.

Your Latitude, Written in the Sky

Here is the elegant part. The height of Polaris above the horizon, measured in degrees, is equal to your latitude. Stand facing north, stretch one arm out at eye level, and use your hand as a rough protractor: a closed fist at arm's length spans about 10 degrees, and a thumb about 2 degrees. From London, at roughly 51 degrees north, Polaris stands a little over five stacked fists above the horizon. From Edinburgh, at nearly 56 degrees north, it is a touch higher. From Cornwall it sits slightly lower.

Test it against a known figure on a map. Once the measurement lines up, you have confirmed both your position and your technique — and you have done, with a bare hand, exactly what navigators did with a quadrant three centuries ago.

Orienting Charts and Finding Your Bearings

Face Polaris and you are facing true north. East is to your right, west to your left, and south is directly behind you. The difference between this and magnetic north is only a degree or two across Britain, which is close enough for stargazing and for most walking purposes on a clear night.

This is what makes Polaris so practical when you are holding a star chart or a planisphere. Hold the chart above your head — not in front of your face — with the direction marked north pointing towards Polaris. The horizon labels on the chart will then match the real horizon around you. Rotate the chart's wheel to your date and time, and the pattern overhead should line up with what you see.

Use the sky's rotation to work out direction as the night wears on. Everything turns anticlockwise around Polaris at about 15 degrees per hour, so a star that was due east two hours ago is now roughly 30 degrees round towards the south. Stars rise in the east, set in the west, and anything crossing due south is at its highest. If you lose your bearings, find one bright star you recognise, note where it sits relative to Polaris, and reason it out from there.

Getting the Most from Your First Attempts

Give your eyes twenty minutes to adapt to the dark, and resist the urge to check your phone — one bright screen undoes the whole process. A red torch, or a torch dimmed as low as it will go, preserves your night vision while you consult a chart.

• Choose your spot: you need an open view to the north, away from streetlights. A garden, a park or a quiet lane will do.
• Use binoculars if you have them: 10x50s will reveal the fainter stars of the Little Dipper, making the whole pattern much easier to confirm.
• Go out at the same time for a week: recognising the Plough, Cassiopeia and Polaris will become automatic surprisingly quickly.
• Keep a rough sketch: drawing what you see, even badly, fixes the pattern in your memory far better than looking alone.

Polaris is patient. It will be in the same place tomorrow night, next month and next decade, so there is no hurry and no penalty for a cloudy evening. Learn it once and you will have a permanent reference point for every other thing you find in the sky.