What is the North Star? Is the North Star always north?
The North Star, or Polaris, is a very special star that sits almost directly at the Earth’s North celestial pole. It’s the only bright motionless star in the sky. It’s a more consistent navigational tool than a magnetic compass. But today's North Star won't stay still forever. Why is that? In this article, you'll discover why and learn more about the modern North Star.
Contents
- North Star name
- What star is the North Star?
- Where is the North Star tonight?
- What makes the North Star, Polaris, special?
- North Star Navigation
- FAQ
- Bottom line
North Star name
The “North Star” is the rank rather than the name of a particular star. It describes the closest star to the Earth’s North celestial pole. The North celestial pole, in its turn, is one of the two points in the sky where the Earth’s axis of rotation intersects the celestial sphere. Thus, the North Star is a star sitting closest to the Earth’s rotational axis. Nowadays, Alpha Ursae Minoris is the star that fits the definition.
What is the North Star called?
The current North Star is called Polaris. This name comes from the Latin “Stella Polaris,” which means “Pole Star”. In Ancient Greece, the North Star was called “Kynosoura,” translated as “the dog's tail.” This word became the Latin “cynosure,” which is still used today to mean the center of attention or something that serves as a guide.
Some other figurative names for the North Star are the Pointer, the Star of the Sea, the Steering Star, the Lodestar, and the Star at the Top of the Heavenly Mountain. They all indicate the great importance of this star in life and culture.
The scientific name of the modern North Star is Alpha Ursae Minoris. Its most popular catalog names are HIP 11767, HR 424, HD 8890, TYC 4628-237-1.
What constellation is the North Star in?
As mentioned earlier, the closest star to the North celestial pole in modern times is Alpha Ursae Minoris. As its name suggests, it’s a part of the constellation Ursa Minor (or “the Little Bear”).
Is Sirius the North Star?
No, Sirius is a completely different star located in the constellation Canis Major (“the Great Dog” constellation). It’s the brightest star in the night sky. You can learn more about the constellation Canis Major and its stars in our dedicated article.
What star is the North Star?
- Official Name: Alpha Ursae Minoris, α UMi
- Alternative Names: Polaris, Pole Star, North Star
- Catalog designations: HIP 11767, HR 424, HD 8890, TYC 4628-237-1
- Constellation: Ursa Minor
- Star type: Triple star system (yellow supergiant Polaris A, white main-sequence stars Polaris Ab and Polaris B)
- Right ascension: 2 h 31 m 49.08 s
- Declination: +89° 15′ 50.8″
- Mass: 5.4 solar masses
- Luminosity: 1,260 L (2,500 times brighter than the Sun)
- Diameter: 70 million km (50 times bigger than the Sun)
- Temperature: 6,015 K
- Distance from the Earth: 132.76 parsecs or 433 light-years
- Rotation period: 119 days
Polaris is a variable star. It means its apparent magnitude changes with time. Also, it is, in fact, a triple star system that contains yellow supergiant Polaris A and two smaller stars Polaris Ab and Polaris B. You can see the more distant companion, Polaris B, even with a small telescope, but Polaris Ab is too close to the main star to be seen.
Polaris star color
All three stars in the Polaris system are of spectral type F. Such stars are typically white or yellow-white in color. However, their yellowish hue is very faint, so most stargazers will see Polaris as a white, medium-bright star. With the unaided eye, observers will only spot the light of the main star, a yellow supergiant Polaris A, but the other two are very similar in color.
Where is the North Star tonight?
The North Star is located in the constellation Ursa Minor. It’s not exactly at the North celestial pole, but about 0.65° away, so it actually moves a little bit. The star makes a small circle about 1.3° in diameter around the North celestial pole, though it still appears motionless to the unaided eye. The North Star always points due north, but depending on your latitude, its position in the sky will be higher or lower, and it will disappear from view when you reach the Southern Hemisphere.
How to find the North Star from the Big Dipper?
The Big Dipper is part of the Ursa Major constellation and the most prominent asterism in the sky. Fortunately, it’s also the closest to Polaris! So, you can easily find Polaris with the help of two bright stars — Merak and Dubhe — which build the outer part of the Big Dipper’s bowl. Draw an imaginary line from Merak to Dubhe and extend it about five times the distance between the two stars. Polaris will be the brightest star in this direction. Check out our infographic for a visual explanation.
How to find Polaris with Sky Tonight?
If you need help finding Polaris, use the stargazing app Sky Tonight. Here is how to do it:
- Launch the app and type “Polaris” in the search bar.
- Tap on the relevant result to get more information about the star.
- Tap on the blue target button in the lower right corner of the screen. The app will show you the location of Polaris on the sky map.
- To find Polaris in the sky above you, tap the compass button or point your device at the sky. You’ll see the white arrow on the screen. Move your device to follow the arrow until you see Polaris. The position of the star on the screen matches the real sky.
What makes the North Star, Polaris, special?
Over the course of a night, Polaris moves less than any other visible star in the sky. The main reason is that it’s almost aligned with the Earth’s rotational axis. As the Earth rotates, the North Star appears motionless, like the tip of a spinning top, and the other celestial objects seem to move around it throughout the day. But, like a spinning top, the Earth wobbles as it spins, tracing a cone of 23.5° radius with its axis. This motion is called the precession of the Earth's axis. Each gyration around the cone takes 25,800 years, which causes, for instance, the zodiac constellations to shift and the North Star, too. Later in the article, we’ll reveal when Alpha Ursae Minoris will give place to the new North Star. But spoiler: it won’t be soon.
In addition, the distance to Alpha Ursae Minoris, the modern North Star, is so great that we don’t notice the star’s movement as the Sun rotates and the Earth revolves around the Sun. By some estimates, these motions would shift the apparent position of Polaris in the sky by only about 0.0001 degrees over the course of the year. Good luck trying to notice the difference!
Polaris moves around the center of our galaxy at about the same speed and in a similar direction as the Sun. So, its motion doesn’t really change where it is in the sky, but even if it did, it would take hundreds of millions of years.
Has Polaris always been the North Star?
Around 2600 BC, when the ancient Egyptians built the pyramids, the North Star was a dim star called Thuban in the constellation Draco. Alpha Ursae Minoris, or Polaris, only became the North Star around 500 AD due to the precession of the Earth’s axis we mentioned earlier. As the Earth slowly wobbles, Polaris will move closer in line with the Earth’s axis of rotation. On March 24, 2100, Polaris will be at its closest point to the North celestial pole, at declination +89°32′50.62″. Remember the date!
What is the next North Star?
After the year 2100, Polaris will slowly move away from its northernmost point, and by the year 4000, the star Errai (Gamma Cephei) will take its place.
And here is the list of all the other stars that will be North Stars in the more distant future:
- Alderamin (Alpha Cephei) by 7900;
- Deneb (Alpha Cygni) by 10,223;
- Vega (the brightest North Star in the following millennia) by 13,600;
- Rastaban (Beta Draconis) or Eltanin (Gamma Draconis) as the closest stars to the North celestial pole by 16,100;
- Edasich (Iota Draconis) by 20,500;
- Kochab (Beta Ursae Minoris) by 23,800.
Alpha Ursae Minoris (the modern Polaris) will finally return to its place by the year 25,800.
North Star Navigation
Where is north?
Once you’ve found the North Star in the sky, you’ll find it easier to navigate on the Earth. The star always points due true north. So, face the North Star and extend your arms sideways:
- North is in front of you.
- Your right hand is pointing east.
- Your left hand is pointing west.
- South is behind you.
Best way to locate north in the Northern Hemisphere
The North Star works better than a magnetic compass for finding the true north. While a compass tells you where magnetic north is, the North Star points due true north, so you don't have to deal with the magnetic declination, which can vary from place to place. Also, a compass errs because of local magnetic influences, and the North Star always points about the same direction. It’s only 0.65 degrees away from the North celestial pole.
What is the altitude of Polaris above the northern horizon for the observer?
You can use the North Star to find out how far away north from the Equator you are right now, which is your current latitude. It was essential for navigation in the sea or deserts in the past, but even now, it may be fun to learn.
The height of Polaris in the sky (its altitude) corresponds to the latitude at which you are located. If you see Polaris right above your head, at the zenith — you are lucky to be in the center of the North Pole, and your latitude is 90°. The closer you get to the Equator, the lower Polaris will stay in the sky. For example, in Minneapolis (Minnesota, US), Polaris lies in the middle of the celestial sphere because the city’s latitude is 45° — a point midway between the Equator and the North Pole. The Equator is at zero latitude, so Polaris hides from view as soon as you reach it.
You can check the Polaris altitude in Sky Tonight. Type “Polaris” in the search bar, tap on the matching result and go to the “Figures” section. The number in the “Alt” (altitude) row is the height of Polaris, which is approximately the latitude of your device’s location.
FAQ
What is Polaris?
Polaris is the other name for Alpha Ursae Minoris, which is the closest star to the North celestial pole nowadays. It’s the brightest star in the constellation Ursa Minor and the most important star for navigation in the Northern Hemisphere. Check your knowledge of the stars and their locations with our quiz.
What constellation contains the North Star?
Polaris, or the North Star, is located in the constellation of Ursa Minor at the tip of the Little Bear’s tail. It also marks the end of the handle of the Little Dipper asterism. Find the North Star and other stars in the sky easily with our colorful guide.
Is the North Star part of the Big Dipper?
No, the North Star is a part of the Little Dipper, the asterism of the Ursa Minor constellation. Learn about the brightest stars in the Big Dipper and the Ursa Major constellation in our dedicated article.
Is the North Star the brightest star?
Despite the common misconception, the North Star isn’t the brightest star in the sky, it’s only the brightest in its home constellation Ursa Minor and about the 50th brightest star overall. The brightest star in the night sky is Sirius. You can learn about this dazzling star in our dedicated article.
Can you see Polaris from the Equator?
If you are observing the sky from sea level with a perfect view of the horizon, you may notice Polaris about 0.5° south and north of the Equator, as the star is a bit away from the north celestial pole. Further south, Polaris disappears from view. Find out what stars are the best visible in the sky with our colorful infographic.
Bottom line
Alpha Ursae Minoris is the North Star in the sky of the modern age. It doesn’t seem to move because it’s right above the Earth’s axis of rotation, but in fact, it moves slowly across the sky, just over hundreds of years. In the year 4000, its place will be taken by the star Errai. Until then, we can use Polaris to navigate in the Northern Hemisphere. Find Polaris with the astronomy app Sky Tonight and let it help you navigate on Earth.
