How to Find the North Star (Polaris) Using the Big Dipper

Many people assume the North Star is the brightest star in the sky. It is not. NASA's skywatching team puts it plainly: "The North Star isn't the brightest star in the sky, but it's usually not hard to spot, even from the city." The trick is knowing where to look, and the easiest guide is a star pattern most people already recognize: the Big Dipper.

This guide covers the three-step method, why Polaris stays put while other stars wheel around it, and a neat way to read your latitude from the sky.

Why Polaris matters

Polaris sits almost directly above Earth's North Pole, along the line of the planet's rotation axis. NASA explains that it lies "quite close to the point in the sky where the north rotational axis points," a spot called the north celestial pole.

Two useful things follow from that:

• It marks true north. NASA notes that Polaris is "located in the direction of true north (or geographic north, as opposed to magnetic north)." Face Polaris and you are facing north.
• It barely moves. As Earth turns, other stars sweep out circles around the pole over the course of the night. Because Polaris is so close to the pole, NASA says it "traces out a very small circle over 24 hours," so it stays in roughly the same place all night, every night.

Step 1: Find the Big Dipper

The Big Dipper is not a constellation by itself. The International Astronomical Union, which maintains the official list of constellations, describes it as an asterism: "the seven bright stars in Ursa Major," known as "the Plough" in Europe and "the Big Dipper" in America. Four stars form a bowl, or cup, and three form a curved handle.

Look toward the northern part of the sky. Depending on the season and time of night, the Dipper may appear upright, upside down, or standing on its handle, because it circles the pole like every other star near it.

Step 2: Find the two pointer stars

Look at the end of the bowl farthest from the handle. The two stars that form that outer edge are the "pointer stars." Royal Museums Greenwich, home of the Royal Observatory, names them: Polaris can be found "by following a line drawn through Dubhe and Merak, the two end stars in the bowl part of Ursa Major."

Step 3: Follow the line to Polaris

Draw an imaginary line from Merak (at the bottom of the bowl's outer edge) through Dubhe (at the top) and keep going out of the open side of the bowl. The first moderately bright star along that line, sitting fairly alone, is Polaris.

To confirm it, NASA notes that Polaris is "the tip of the handle of the Little Dipper," the tail of the little bear in the constellation Ursa Minor. The Little Dipper's other stars are fainter, so in a bright suburban sky you may only see Polaris and a couple of its neighbors.

Read your latitude from Polaris

Royal Museums Greenwich adds a detail sailors relied on for centuries: "the angle of the star above the horizon gives you your latitude." That gives you a simple check on whether you found the right star:

Where you are	Approximate latitude	How high Polaris appears
Near the equator	0 degrees	On the northern horizon
Miami, Florida	About 26 degrees north	Low in the north
Denver, Colorado	About 40 degrees north	A little below halfway up (halfway is 45 degrees)
Oslo, Norway	About 60 degrees north	High in the northern sky
North Pole	90 degrees north	Directly overhead

NASA confirms the extreme case: Polaris "would appear directly overhead if you stood at the north pole." If the star you picked is far higher or lower than your latitude suggests, you probably have the wrong one.

What about the Southern Hemisphere?

South of the equator, Polaris is below the horizon. NASA notes that the Southern Hemisphere "doesn't have a bright star that marks the south celestial pole," and observers there use other methods, including the stars of the Southern Cross, to find due south.

Polaris will not always be the North Star

The title passes from star to star over long periods. According to NASA, Earth's rotation axis wobbles "over the course of about 26,000 years," like a spinning top, so the celestial pole slowly drifts past different stars. NASA says the pole pointed toward the bright star Vega about 14,000 years ago and will point toward Vega again in about 12,000 years.

A few facts about the star itself

Royal Museums Greenwich describes Polaris as a pulsating supergiant, a type of star often many hundreds of times larger and much brighter than the Sun. It looks modest to us only because it is so far away: about 431 light-years. The light you see tonight left Polaris roughly 431 years ago.

Quick checklist for your first night

1. Face roughly north, away from the brightest nearby lights.
2. Find the seven stars of the Big Dipper.
3. Locate the two stars at the outer edge of the bowl, Merak and Dubhe.
4. Follow their line out from the bowl to the first moderately bright star.
5. Check its height against your latitude.

Key takeaways

• Polaris is not the brightest star, but it is easy to find from the Big Dipper's two pointer stars, Dubhe and Merak.
• It sits close to the north celestial pole, so it marks true north and barely moves through the night.
• The Big Dipper is an asterism of seven bright stars within the constellation Ursa Major.
• Polaris's height above the horizon roughly equals your latitude, from the horizon at the equator to straight overhead at the North Pole.
• Earth's 26,000-year wobble means Polaris is only today's North Star; Vega will take the role again in about 12,000 years.