Polaris Star: A Guide to Spotting the North Star in the Night Sky

If you’ve ever gazed at the night sky in the Northern Hemisphere, you might have noticed that one bright star around which everything seems to rotate. This is the Polaris Star, also known as the North Star, located about 430 light-years from Earth and part of the constellation Ursa Minor.

For centuries, Polaris has served as a crucial point of navigation, helping travelers find their way north, as it stays nearly fixed while other stars seem to spin around it in the night sky. Let’s explore the features of this luminous guide and learn how to easily spot it.

What Is Polaris?

Polaris, also referred to as the North Star, Northern Star, or Pole Star, is a prominent celestial body in the Northern Hemisphere. It can be found in the constellation Ursa Minor, also known as the Little Bear or the Little Dipper. Positioned nearly in line with Earth's rotational axis, it stays almost fixed above the North Pole.

Polaris is actually part of a trinary system, made up of Polaris A, the main star, along with two smaller companions, Polaris B and Polaris Ab. A trinary system in astronomy consists of three celestial objects that are gravitationally bound together.

Although known for its seemingly unchanging position in the sky, Polaris A is far from motionless; it is a supergiant star, roughly six times the mass of the Sun, located about 323 light-years away from Earth. It pulsates, with its brightness fluctuating in a regular cycle, and is classified as a Cepheid variable star.

While Polaris is currently the North Star, its reign is temporary due to a gradual shift in Earth's axial tilt, known as axial precession. In roughly 12,000 years, another brilliant star, Vega, will take over as the new North Star, replacing Polaris as our celestial guide in the night sky.

Polaris Doesn't Rise or Set

Polaris is known as the North Star because its position in the night sky is nearly directly above the North Pole, according to Rick Fienberg, a Harvard-trained astronomer and former press officer for the American Astronomical Society.

As Fienberg explains via email, "If you were standing at the North Pole — latitude 90 degrees north — at night and looked straight up, Polaris would be directly overhead. From other locations in the Northern Hemisphere, facing due north at night and gazing at an angle above the horizon equal to your latitude (for instance, looking about halfway up — 45 degrees — if you're in Portland, Oregon, at latitude 45 degrees north), Polaris will appear shining at that spot."

Polaris stands out because, unlike other stars, it remains in the same spot every night from dusk until dawn, neither rising nor setting, says Fienberg. Its constant presence often leads people to mistakenly believe it's the brightest star in the sky (though it is actually the 48th brightest).

Despite this, Polaris is about 2,500 times more luminous than our sun due to its greater mass and larger size. However, its distance from Earth, while still visible to the naked eye, reduces its apparent brightness.

Has Polaris Always Been the North Star?

It might be surprising, but Polaris hasn’t always been the North Star. In fact, during the Ancient Egyptian Old Kingdom, which spanned from around 4,700 to 4,100 years ago, a different star held the title, symbolically represented by a female hippopotamus, as described in Giulio Magli's book, "Architecture, Astronomy and Sacred Landscape in Ancient Egypt."

This is because the star we see as the North Star has shifted over time.

"If you think of a line drawn between Earth's North and South Poles as the axis on which Earth rotates, that axis is slowly moving in a circular path," explains Christopher Palma, associate dean of the Eberly College of Science at Penn State University, in an email. "This movement is often compared to the wobble of a spinning top or coin before it tips over. We call this motion Earth's North Pole 'precessing,' meaning the line from the North to the South Pole traces out a circle over a period of 26,000 years."

As a result, "over very long timescales (spanning thousands of years), the North Pole shifts in relation to the stars," Palma adds. "So, thousands of years ago, people on Earth observed the star Thuban in the constellation Draco as the North Star, instead of Polaris."

How to Find the North Star in the Sky

Locating the North Star is both an enjoyable and practical skill, especially when navigating after dark. To get started, make sure you’re in an area with little light interference. Polaris will always be positioned directly north and is roughly aligned with your latitude, appearing higher in the sky the farther north you are.

The North Star in Navigation

The star Polaris was first documented by the astronomer Claudius Ptolemy, who lived during the second century C.E. Its location, near the celestial North Pole, later became invaluable to navigators in their journeys.

"At night, in the Northern Hemisphere, if Polaris is visible, you can always determine which direction is north (and, consequently, south, east, and west)," says Fienberg. "This has been true for hundreds of years, including during the Age of Exploration in the 15th to 17th centuries, and will remain true for centuries to come. Additionally, you can determine your latitude by observing the angle from the horizon to Polaris, which closely matches your latitude (within a degree or so). However, once you move south of the equator, Polaris dips below the horizon and is no longer useful for navigation."

However, when using Polaris for navigation, it's important to remember that the star isn't exactly positioned above the North Pole. Instead, it has a slight offset of 39 arc-minutes, explains Rich Schuler, a professor of astronomy, in an email interview. (He authored a 2002 primer on the North Star in Scientific American.) This corresponds to an error of approximately 44.7 miles (72 kilometers).

Here's Why the North Star Twinkles

An interesting feature of Polaris is that it is classified as a Cepheid Variable, a type of star that pulsates radially. These stars vary in both size and temperature, causing their brightness to fluctuate in a consistent, predictable cycle with defined periods and amplitudes.

"The pulsation occurs because the star is in an unstable state," explains Palma. "It expands, and when it does, an outer layer becomes transparent, causing the star to cool. As it cools, it shrinks until it becomes opaque again, at which point it heats up and expands once more. This cycle repeats, causing the star to pulsate and its brightness to fluctuate."