Polaris: How to Find the North Star

Polaris, the North Star, is the most important star for navigation in the Northern Hemisphere. Sitting less than a degree from the north celestial pole, it remains nearly motionless while every other star appears to rotate around it. Despite its fame, Polaris is only moderately bright, and many people are surprised to learn it is not among the top 40 brightest stars. Find it easily with StarGlobe.

How to Find Polaris

The classic method uses the Big Dipper in Ursa Major. Locate the two stars at the outer edge of the Dipper's bowl, Dubhe and Merak, called the Pointer Stars. Draw an imaginary line from Merak through Dubhe and extend it roughly five times their separation. The first moderately bright star you encounter is Polaris.

An alternative method uses Cassiopeia, which sits on the opposite side of Polaris from the Big Dipper. From the deeper V in Cassiopeia's W shape, a line through the central star points roughly toward Polaris. This method is useful when the Big Dipper is low on the horizon or obscured.

Polaris marks the end of the handle (or tail) of the Little Dipper in Ursa Minor. Once you find Polaris, the rest of the Little Dipper extends away from it, though the other stars are faint and require darker skies.

Why Polaris Stays Fixed

Earth rotates on an axis that points very nearly at Polaris. As the planet spins, all the stars appear to trace circles around this axis, but Polaris sits so close to the pivot point that its motion is imperceptible. This is why Polaris appears to stand still while the rest of the sky rotates around it.

The angle of Polaris above the horizon equals your geographic latitude. At the North Pole, Polaris is directly overhead. At the equator, it sits on the horizon. At 40 degrees north latitude, it appears 40 degrees above the northern horizon. This simple relationship has made Polaris an invaluable tool for sailors, explorers, and travelers for centuries.

Physical Properties

Polaris is far more than a navigational marker. It is a yellow supergiant about 430 light-years from Earth, roughly 45 times the Sun's diameter and about 2,500 times its luminosity. It is also a Cepheid variable star, pulsating in brightness with a period of approximately 3.97 days. The amplitude of its brightness variation has been decreasing over the past century, dropping from about 0.15 magnitudes to roughly 0.03 magnitudes, a change that has puzzled astronomers.

Polaris is a triple star system. The primary, Polaris Aa, is the supergiant Cepheid. A close companion, Polaris Ab, orbits very close to the primary and was only resolved through spectroscopy and later by the Hubble Space Telescope. A more distant companion, Polaris B, at magnitude 8.7, is visible in small telescopes about 18 arcseconds from the primary and provides a satisfying view for amateur observers.

Polaris Through the Ages

Polaris has not always been the pole star. Earth's rotational axis undergoes a slow wobble called precession, tracing a circle among the stars over a period of about 25,772 years. Around 2700 BCE, the pole star was Thuban in Draco. Around 12000 BCE, Vega was near the pole. Polaris reached its closest approach to the exact celestial pole in 2012 and will gradually drift away over the coming centuries.

The ancient Greeks knew Polaris but did not rely on it for navigation because it was further from the pole in their era. They used the constellation Ursa Major as a general indicator of north. By the medieval period, Polaris had moved close enough to the pole to become the primary navigational star, and it played a crucial role in the Age of Exploration.

Polaris in Culture and Navigation

Polaris has carried many names across cultures. It has been called the Lodestar (guiding star), Stella Polaris, the Star of Arcady, and Cynosure (from the Greek name for Ursa Minor). In many languages, its name simply translates to "north star" or "nail of the sky."

For practical navigation, finding Polaris instantly gives you north. All other cardinal directions follow: south is directly behind you, east to your right, and west to your left. This technique requires no equipment and works from any location in the Northern Hemisphere on any clear night.

In the Southern Hemisphere, there is no bright star near the south celestial pole. Southern navigators use the Southern Cross and its pointer stars, or the constellation Octans, to approximate south.

Best Time to Observe

Polaris is visible every clear night of the year from anywhere in the Northern Hemisphere. It does not rise or set and maintains the same altitude above the horizon year-round. Its steady position makes it observable in every season, though the surrounding constellations change with the time of year.

Polaris is not visible from the Southern Hemisphere. It drops below the horizon for observers south of about 1 degree north latitude.

Neighboring Stars and Constellations

Polaris anchors Ursa Minor, with the Little Dipper extending from it. Cassiopeia lies on one side and Ursa Major on the other. Draco winds between the two bears. Cepheus borders the pole region to the northeast. All of these circumpolar constellations are visible year-round from mid-northern latitudes and can be explored with StarGlobe.

Quick Facts

Polaris has an apparent magnitude of 1.98, a distance of approximately 430 light-years, and a luminosity about 2,500 times that of the Sun. It is a Cepheid variable with a period of 3.97 days. The star currently sits about 0.7 degrees from the north celestial pole. Its right ascension is approximately 2h 32m, and its declination is +89 degrees 16 minutes.