Polaris occupies a special place in the night sky. As the Earth revolves around its axis, all the northern sky’s stars appear to rotate around the North Celestial Pole (NCP). Polaris is located just half a degree from NCP, so it appears stationary to the observer while the other stars slowly move positions.
Polaris, a star typically referred to as the North Star, is part of the constellation Ursa Minor and its position is set close to the North Celestial pole. As the brightest star in Ursa Minor, Polaris is easily visible from the Northern Hemisphere and has been used for navigation by sailors and travelers for centuries.
Due to the Earth’s spherical shape, Polaris’s observable position is determined by the observer’s latitude. For instance, at zero degrees latitude (equator), Polaris is on the northern horizon. However, if you move to Houston, Polaris will appear 30 degrees north of the horizon.
This dance continues until the observer views the night sky from the geographic North Pole, where at 90 degrees latitude, Polaris will be located directly above your head.
What is the North Star?
Polaris (a.k.a. The North Star) is the brightest in the constellation Ursa Minor. The star itself is notable for being the star closest to the Northern Celestial Pole, making it the ideal marker for True North: Its elevation means that you can use it for navigation.
The North Star is a very luminous star that is visible at night, though we should mention that it’s not the brightest star overall. Polaris doesn’t even make it to the list of the 40 brightest stars in the night sky. It is only the 48th brightest star visible by the naked eye.
Located approximately 434 light-years from Earth, Polaris is indeed very far from our planet. Polaris is known by other names such as the Northern Star Pole Star, Guiding Star, Lodestar, and Cynosūra; a Greek word for dog’s tail. Before Ursa Minor became known as The Bear, ancient Greeks used a different star representation: a dog.
What is Polaris?
Polaris – Alpha Ursae Minor
| Distance | 323 – 433 light years (99 – 133 parsecs) |
| Parallax | 7.54 ± 0.11 mass |
| Radial velocity | -17 km/s |
| Proper motion | RA: 198.8 ± 0.20 mass/yr == Dec -15 ± 0.30 mass/yr |
| Constellation | Ursa Minor |
Polaris is a shortened form of the Latin stella Polaris, a term that was coined back in the Renaissance era at a time when the star reached close to the celestial pole with a difference of a few degrees. The first time people used the name Polaris was in 1547 when Gemma Frisius described it as stella illa quae Polaris dicitur. It translates to “the star called Polaris.” At the time, the star was measured to be between 3°- 8° from the North Celestial Pole.
The name became official in 2016 when the International Astronomical Association designated the North Star as “Polaris” following a concerted effort to organize standardized star names. In ancient times, Polaris had not yet moved to become the star closest to the celestial pole. Instead of using a single star for navigation, the entire constellation Ursa Minor was used by navigators.
The star eventually became the true North Star when it moved close enough to the celestial pole in medieval times – even though it was still off-the-mark by a few degrees. Numerous writings have since referred to the star as the Pole Star, creating the North Star’s history that we study today.
Polaris eventually became a steadfast star, symbolizing a non-changing aspect of the night sky. Consequently, the star made it to famous writings by the likes of William Shakespeare and Julius Caesar. Ancient Inuit astronomy depicts Polaris in their coat of arms and flag – which is still evident in specific territories of Canada and Alaska.
Why is Polaris the North Star?
Polaris is a part of a cycle that takes around 26,000 years to complete, called the processional cycle. A cycle that moves the entire Northern Celestial Pole counterclockwise to bring an individual star close to the celestial pole. Whichever star sits at this position becomes the North Star.
Just 5,000 years ago, the North Star was a star in the constellation Draco known as Thuban. At that time, it appeared stationary in a space where the other stars appeared to turn. In fact, some astronomers consider Thuban as a better North Star than the current Polaris because its position at the time pinpointed the celestial pole more accurately than Polaris does today (to a difference of only 0.2°).
Bear in mind that our current North Star is still in motion. Or rather, the position of the Earth along its rotational axis is constantly changing, and this means that the visible position of the star to an observer will change over time to a point where Polaris will reach closer to the ideal celestial position that it is today.
Even with this position adjustment, Polaris still won’t make a more accurate North Star than Thuban.
Having said that, Polaris shouldn’t be undervalued for the role it plays today as the North Star. Polaris is one of the brightest of the visual stars in the night sky and can easily be spotted from just about any location in the Northern Hemisphere (and people in the equator can see it as well). It helps orient yourself when you need to determine your position relative to the North Pole. Travelers use it when navigating through trackless deserts, the seas, and when flying planes. There was a time when Polaris served the purpose of guiding sailors through the seas, and this allowed lots of civilizations to thrive through trade and expansion as people crossed new frontiers without fear of getting lost or becoming stranded.
Why is the North Star so bright?
Polaris has a brightness range of between 1.86 and 2.13; however, this amplitude is constantly changing due to changes brought on by internal pulsations and the star’s relative distance to Earth. In the early 1960s, Polaris’ brightness amplitude was 0.1, but it started increasing drastically in the subsequent years. Astronomers report that Polaris increases its brightness, possibly due to a secular redward evolution occurring across Cepheid star systems.
As far as temperature goes, Polaris’ heat varies by a minimal extent, even during pulsations. Still, these variations are difficult to predict due to the erratic changes that come with each new cycle. A report from the journal Science suggests that Polaris is at least twice as bright today as it was back when Ptolemy first observed it in the night sky. If true, this would mean that our North Star has changed from third to second magnitude – a dramatic development for stellar evolution.
Because this star remains stationary in the celestial pole, observers have an easy time locating it in the night sky as the other northern stars appear to rotate around it. Despite it not being the biggest or brightest star in the northern sky, Polaris does appear significantly bright and easy to spot. At some point, Polaris will move away from the celestial pole as it happens during the procession of equinoxes.
What is the easiest method you can learn to locate the North Star?
Polaris is classified as a Population I Cepheid Variable – which essentially means that its brightness in the night sky varies. But still, it is the brightest star in Ursa Minor, a constellation more commonly referred to as Little Dipper. The Polaris system comprises multiple stars, the largest of which is called Polaris A, a giant star that measures six times our sun’s size. Other stars in this constellation are much smaller by comparison.
So how can I locate Polaris?
Polaris sits at the far end of the Little Dipper’s tail, and to find it, observers should start by locating the Big Dipper in the night sky. Once you have it in sight, focus on the two pointer stars at the end of the Dipper’s bowl. These stars are called Merak and Dubhe, and if you draw an imaginary line between these two stars going north (or south depending on the season), they will point you directly to the North Star.
Remember, the North Star is always visible in the Northern sky, but it appears lower in the night sky the more south you go and seems to climb higher in the sky as you go north. As a result, navigators can also use it to determine not only direction but latitude as well.
We should point out that astronomers have had a difficult time through the years when analyzing Polaris’s exact distance from the Earth. This table shows the differences in terms of distance, as studied and published by renowned scientists in recent years. It’s not yet clear which of these distances is the most accurate.
| Year | Component | Distance (Light Years) | Notes |
| 2006 | A | 330 ly | Turner |
| 2007 | A | 433 ly | Hipparcos |
| 2008 | B | 359 ly | Usenko &v Klochkova |
| 2013 | B | 323 ly | Turner et al. |
| 2014 | A | 385 ly | Neilson |
| 2018 | B | 521 ly | Bond |
| 2020 | B | 447 ly | Gaia |
Here are some additional facts about the North Star:
1) Star System
Polaris is located in a triple star system that includes a massive yellow star called Polaris Aa and two other stars known as Polaris Ab and Polaris B. The first two stars are in close proximity and orbit each other while Polaris B orbits the pair.
The biggest star in this system, Polaris Aa, is a Cepheid that happens to be closer to Earth than other stars of its kind and is a frequent focus of astronomical study as a result. These types of stars are used for measurements of distances in space because they contain known luminosities. In fact, they are part of the reason that famous astronomer Edwin Hubble proved that Andromeda was not a nebula located inside the Milky Way as previously thought, but rather a distinct galaxy on its own.
2) Polaris as the North Star
Polaris’ position in the celestial pole is slightly off the north axis by a 7th of a degree — though this will change with time as our planet rotates along its axis. However, for the observer viewing the star with their naked eye, it appears to sit directly north of the celestial pole. As of now, Polaris is still moving closer to the celestial pole, where its peak location will be slightly closer to an exact northern position relative to the celestial pole. Keep in mind that the understanding of our planet’s movement through space is a good foundation for anybody hoping to make sense of the differences in the position of the North Star.
By studying the past, you can get a reasonably clear picture of what the northern sky looked like to ancient civilizations – some of whom possessed tremendous knowledge of the stars.
There is a slow shift in the Earth’s positions along its rotational axis where after about 26,000 years, the existing North Star moves further out of alignment with the northern pole to a point where a different star or constellation can take its place as the next North Star. It is also true of Polaris Australis, the South Star, which at the moment is Sigma Octantis.
3) Polaris quick facts
Polaris’s actual distance to the celestial north has an interesting effect on how we view the star and the information we can get from it. From the observer’s viewpoint, the distance from the horizon to Polaris will match their own latitude. For instance, if you view Polaris from a point in New York where your latitude will be 41°, Polaris will appear at 41° above the horizon.
The whole area around Polaris is populated with a semicircle of stars called the Engagement Ring. To pinpoint Polaris, check for the diamond sign in the ring that’s made by about a dozen stars, some very bright, some a little dimmer.
4) How far is Polaris?
The exact distance from Earth is not clear; however, the most mainstream recorded distance is 433 light-years. There have been more recent adjustments to this number, with some astronomers placing it at 323 light-years or 99 parsecs. Accuracy in measuring the North Star’s distance has been questioned due to Cepheid binary star systems’ variable nature. Despite many experts’ attempts to determine Polaris’s distance, no specific distance has been entirely accepted by a majority of astronomers.
5) Polaris brightness
After decades of research, astronomers have determined that Polaris is at least four times brighter today than when first recorded by Ptolemy in 137 CE. Starting in 1999, a group of researchers began tracking Polaris to measure brightness changes, and the results showed that the star’s pulsations increased and decreased randomly, affecting its brightness amplitude. Going back centuries, scientists found that Polaris has become brighter over the years.
6) What’s so special about Polaris?
Astronomers have long been fascinated with Cepheids because they have a certain consistency that allows people to study space using them as “candles” or markers. But having said that, Polaris is a type of Cepheid that displays unusual changes concerning brightness, which means the star goes through more complex processes than is typical of Cepheids.
Besides this, the North Star holds an essential place in astronomy because of its position in the pole, which allows it to play the role of a literal guiding light for people on Earth that need a clear sense of direction to navigate through remote locales. Unfortunately, if it weren’t for its position, this star would be far less interesting to the average person.
What was Earth’s North Star before Polaris?
Polaris became the North Star in around 500 CE, when Kochab, another star in the same constellation, moved to a different system position. Kochab is quite a bright star within Ursa Minor, and it held this position as the North Star for a period beginning in 1500 BCE to 100 CE.
At the moment, the star is known as a Guardian of the Pole along with Pherkad, another star in the Little Dipper. Before Polaris became the bright northern star we know today, navigators used the entire Ursa Minor constellation to determine direction. That is until sometime in the middle ages. When Polaris finally moved close enough to the celestial pole, travelers started using it as the “North Star.”
What will be Earth’s North Star after Polaris?
When Polaris eventually moves out of its current position in its constellation, the subsequent North Star will be Errai, Gamma Cephei. It will be around the year 3000, and the pole will still only be halfway between Polaris and Errai. In the year 4200, Errai will be at its closest point to the celestial pole.
Compared to other North Stars, Polaris is the second most accurately positioned Northern Star after Thuban (Alpha Draconis). Polaris moves to within 0.5° of the pole while Thuban gets as close as 0.2°. The other difference is that Thuban has a far dimmer light, inconvenient for people who rely on the North Star for navigational purposes.
Other stars in the northern sky are used as indicators of true north. These include
- Beta Cephei & Iota (Alpha Cephei)
- Deneb (Alph Cygni)
- Edasich, Tau Herculis, & Iota Herculis (Iota Draconis)
- Kappa Draconis + Kochab (Draco)
- Fawaris (Delta Cygni)
Once it moves out of its position as the North Star, Polaris will again resume its position in the northern sky in the year 27,800. The only difference will be a slight change in proximity to the pole because it won’t reach the same position it did in the year 23,600 BCE when it got extremely close to the pole.
Readers need to understand that Earth tends to wobble on its axis, which is known as procession. Because of this odd movement, people viewing the northern sky won’t always see the same star alignment or the same North Star. The good news is a single wobble takes millennia (26,000 years), so it takes quite a long time before one North Star, and its constellation moves out of position, and another one comes along.
There are times when the northern celestial pole doesn’t have a north star at all, and if there is one, it doesn’t appear fixed as the current Polaris.
In Conclusion
When asked to name a famous star, most people will immediately think of Polaris, our North Star and the guiding star for travelers and sailors for centuries. What makes the North Star significant is its position rather than how bright it appears at night. Even with its somewhat limited brightness in the night sky, many people will be familiar with its name because of its value to humanity.
For much of history, travelers didn’t have any advanced positioning systems or signs that they could rely on to track their movements. Instead, they relied on stars for navigation; and particularly in deserts and the ocean where there was a higher risk of getting lost. Because people could always find Polaris in the sky, it eventually became the most reliable method for determining a direction for many travelers and sailors who spent weeks and months out in the seas.
By locating Polaris, people could quickly determine where East and West were; and as a matter of fact, during the slave era in the south, slaves who escaped captivity used the North Star to find their way as they headed north through the Underground Railroad.
Besides its position, it is also pretty easy to remember Polaris compared to other stars like Fomalhaut or Alberio. But more importantly, Polaris plays a significant role in determining the true north, something that has contributed significantly to successful travel and sailing all over the northern hemisphere and beyond.
FAQ
1. What is the North Star?
The current North Star is Polaris, a star in the constellation Ursa Minor. When viewed from the northern hemisphere, Polaris seems positioned directly above the celestial pole; however, its position is off by about a seventh of a degree. People in the Northern hemisphere identify Polaris by tracking it using two stars in The Big Dipper that point directly (conveniently if you ask me) to the North Star.
2. How bright is the North Star?
The North Star is significantly bright compared to the stars in the night sky; however, it is only recorded as the 48th brightest star visible from Earth. Due to its position and brightness, the North Star is used widely for navigational purposes, both on land and sea. On a clear night, you can quickly determine your location without the aid of a compass by using the Polaris as a reference point.
3. Why is the North Star important?
The North Star appears motionless in the celestial pole, where other stars seem to move around it through the night. Because of its position and steadfastness, the North Star acts as the best and most reliable compass for the true north, which is essential if a person loses their sense of direction in a place where they can’t access a GPS to determine where they are. Different stars have sat directly above the pole and have been used in the same way as the current North Star.
4. Has Polaris always been the North Star?
Thousands of years ago, when the Egyptians were building the pyramids, Thuban was the North Star. It sits in the constellation Draco and actually served as a more accurate North Star than Polaris. However, Polaris is still a reliable North Star, and it’s also brighter than Thuban. Polaris will come to its closest alignment with the pole in March 2100.
5. Does Polaris always point north?
Although Polaris has been visible in the northern sky for a long time, it wasn’t always the North Star it is today. It also won’t remain the North Star forever. The Earth’s movement on its rotational axis means that other star systems will take the position of Ursa Minor in our skies, and at that point, Polaris will cease to be the famous North Star it is today.
6. Is Polaris located near to Earth’s North Pole?
Polaris is the brightest star located in the Northern Celestial Pole, and as such, it appears to remain motionless in the sky. It makes the North Star a reliable star to use for navigation in determining location and latitude. As far as distance is concerned, the star sits about 433 light-years from Earth.
7. How far is the North Star relative to Earth?
Polaris’ distance from Earth is estimated to be between 323 light-years and 433 light-years; however, recent studies have generated speculation as to Polaris’s actual distance – which some scientists believe may be closer than previously thought. High-precision parallax measurements are essential for determining vast distances in space. It is particularly true concerning the North Star, which has raised significant controversy among researchers as most researchers cannot agree on its distance.
8. How can I find the North Star?
Start by locating Ursa Major, the constellation commonly known as “The Big Dipper” or “Big Bear.” Focus on the two outermost stars positioned in the cup of the constellation. These are pointer stars that will guide you to find the North Star.
Ursa Major will be at different positions in each season, but it shouldn’t be challenging to locate in a clear night sky. The two stars in the Big Dipper that are furthest from the tip will point you directly to the North Star if you draw an imaginary line through them. The first easy step to identifying the North Star is learning to locate the Big Dipper and use the pointer stars as guiding points for finding Polaris.
References
Featured image courtesy of Farm 6 Media and Shutterstock.
- Polaris, Wikipedia, https://en.wikipedia.org/wiki/North_Star, Accessed 18/03/2021.
- What Exactly Is The North Star, Scientific American, https://www.scientificamerican.com/article/what-exactly-is-the-north/, Accessed 18/03/2021.
- The North Star: How To Find Polaris, Space, https://www.space.com/15567-north-star-polaris.html, Accessed 18/03/2021.
- Polaris Star Facts, Star-Facts, https://www.star-facts.com/polaris/, Accessed 18/03/2021.
- Finding The Pole Star, Nasa, https://pwg.gsfc.nasa.gov/stargaze/Spolaris.htm, Accessed 18/03/2021.
- Polaris, North Star Research, http://nstarresearch.com/, Accessed 18/03/2021.
- About North Star, North Star Hub, https://www.northstarhub.com/about, Accessed 18/03/2021.
- Why Is Polaris The North Star, Star Facts, https://www.star-facts.com/polaris/, Accessed 18/03/2021.
- North Star Closer To Earth Than Thought, National Geographic, https://www.nationalgeographic.com/adventure/article/121204-north-star-distance-closer-solar-system-space-science, Accessed 18/03/2021.
- Something Strange Is Going On With The North Star, Live Science, https://www.livescience.com/north-star-cepheid-mystery.html, Accessed 18/03/2021.
