How the Sky Turns · 2 of 8

Finding the North Star

How can one star tell you how far north you are?

Two stars in the Big Dipper's bowl point at Polaris, and Polaris tells you your latitude. That is the whole trick.

You’ll be able to find Polaris from the Big Dipper’s pointers, and read your latitude off it.

8 steps · about 6 min

Where and which night

Working out when this is best placed from where you are…

Where

Which night

Date

Time

Kept for this guide only, until you change it here — your map settings, and every other guide, stay as they are.

Print, play outside or present

Present on a big screen

Scan with a phone's camera, or open

Sources

HYG stellar database v4.2 — star positions, magnitudes and every separation quoted here
Evans et al., ApJ 866, 30 (2018) — HST astrometry of the Polaris triple system
Bowditch, The American Practical Navigator (NGA, 2019) — the Polaris latitude correction tables

← GUIDES

More below ↓

With a keyboard, focus the sky, aim it with the up and down arrow keys, and press Enter to drop the pin at the centre of the view; or press Show me.

You are here

Settings

Screen

Night mode Turns every page red, to keep your eyes adjusted to the dark.

High contrast Bolder constellation lines, larger and brighter names on the sky, and stronger text and edges everywhere. Starts on if your device asks for more contrast.

Reduce motion The camera cuts to where it is going instead of flying there, and panels and sheets appear without sliding. Starts on if your device asks for less motion.

Battery saver Draws the sky thirty times a second at most: smoothness traded for battery.

Night brightness Dims the screen below your phone’s lowest setting, down to a fifth, while night mode is on.

Clock and voice

Clock How every time is written. Until you choose, your language’s own clock decides.

D describes What D says about the view on the sky: one sentence, or in full with the field, the constellation and five names.

Sounds Quiet tones as you use the map: a tick as you drag the clock past a mark or dusk, a chime for the star you pick — higher for hotter stars — and a low swell while a figure is out of the dome. Made in your browser, and off until you turn them on.

All settings and your progress

Seven stars: four in a bowl, three in a handle. The Big Dipper (the Plough in Britain) is the best-known shape in the northern sky: the bright part of Ursa Major, the Great Bear. Find it once and you can navigate from it for life.

The two stars at the outer end of the bowl, Merak and Dubhe, are the pointers, 5.4° apart. Your hand is the sky's ruler: at arm's length a little finger covers about 1°, three fingers about 5° — this gap — a fist 10°, and a spread hand, thumb to little finger, about 20°.

Draw the line from Merak through Dubhe and keep going. 29° past Dubhe — three fists — the line arrives somewhere specific. Direction matters: run it the other way and you end up in Leo.

There it is: Polaris, alone at the end of the Little Dipper's handle. Not bright — only the 48th brightest star in the sky — but it has no neighbour of its brightness, so you cannot mistake it. Famous for its address, not its light.

Twelve hours of night: pin your guess, then run it. However the Dipper turns, the arrow still lands on Polaris.

Same night, another hour: the Dipper has turned. Your turn: run the line from Merak through Dubhe again, three fists, and find Polaris.

The pole sinks as you go south. Its height above your horizon (its altitude) is your latitude: 10° a fist.

Earth's axis wobbles; for now, use the pointers.

Pointers, three fists on, to Polaris
Thuban had the job once; Vega will

↺ The pole's ring, from The Wandering Equinox