The sky is full of countless stars, each with unique characteristics. While some shine more brightly than others, one in particular has served special importance. However, it accomplishes little if you don’t know where to look. So, where is the North Star?
What Exactly Is the North Star?
The North Star is a star that sits more or less right on the Earth’s axis. In other words, if you drew a line from the south pole to the north pole and continued that line out into space, you’d eventually reach the North Star. That being said, even at the speed of light, it would take you 430 years to get there.
Also known as Polaris (or Polaris A), the North Star is a supergiant about five times the mass of our own Sun. This size makes it 3,000 times brighter than our star, explaining why it’s so clearly visible even though it’s so far away. The North Star has a magnitude of 2.0 as seen from Earth.
In the late 1700s, Sir William Herschel discovered a distant companion star to Polaris, called Polaris B, that’s too dim to see with the naked eye. A second companion star much closer to Polaris A was identified in just 1929, making the point we refer to as the North Star a three-star cluster.
Which Constellation Does the North Star Belong To?
Polaris is the brightest star in the constellation Ursa Minor, or the Little Bear. This set of seven stars is also frequently called the Little Dipper and definitely looks more the part of a ladle than a bear. It makes up the tip of the bear’s elongated tail or the very end of the dipper’s handle.
Why Is the North Star Important?
The North Star has been significant for generations, as it marks a point in the night sky identifiable as due north. No matter the time of night or time of year, this star is in almost the identical place in the sky. Polaris never rises, and it never sets. Although not the case, it actually looks as if all other stars in the galaxy are revolving around it.
Before seafaring vessels had navigational equipment of their own, sailors could use the North Star to figure out which way they were sailing. Discovering north also meant these sailors knew where west, east, and south were by association. The only time navigators couldn’t depend on Polaris for guidance was during cloudy nights at sea.
Where Will the North Star Be in the Sky?
The answer to this question depends not on the time of year but on your location on Earth. You can use your latitude on terra firma to determine the North Star’s height above the horizon.
For example, people living in San Diego, California, live around 33° degrees north of the equator. Looking up at the sky, inhabitants of the city would be able to see the North Star at 33° above the horizon. Individuals from Mexico city would only need to look up 20° from the horizon to spot Polaris. Norwegians in Oslo would have to look north 60° up from the horizon to catch the tip of the Little Dipper.
Should you continue all the way to the North Pole, you’d have to look up even higher. The North Star at that location would be directly above you at the night sky’s highest point. Folks down at the equator (0° latitude) would be stuck with the North Star perpetually on the horizon.
Our friends from the Southern Hemisphere can only see the North Star when they come north of the equator. Because of Polaris’s location right above our Earth’s axis, it is impossible to see from anywhere in the southern part of the world.
The Trick to Finding the North Star
The North Star is the 48th brightest star in the northern night sky and doesn’t necessarily stand out as anything special. Unless you gaze up at the night sky for hours and watch for a stationary star, you may not be able to quickly locate it. Luckily, a nearby asterism provides an easy trick for finding Polaris.
The Big Dipper is one of the most recognizable objects in the northern night sky, with six stars of second magnitude and one star of the third magnitude. Thanks to their brightness, these stars are some of the first ones visible on a clear night.
The Big Dipper serves as an inverted ladle to the Little Dipper, with the two constantly pouring some celestial liquid into each other. Because of this, the two stars on the far end of the bowl provide the key to finding the North Star. All you have to do is draw a line between these pointer stars.
Starting at Merak in the Big Dipper, draw a line through Dubhe, and continue out into space. Although you’ll pass through the very dim and difficult to see Draco the dragon, you’ll have to travel about five times the distance of Merak to Dubhe to reach the North Star. It will be by far the brightest star you’ll encounter on your line.
Will the North Star Always Be the Same?
Interestingly enough, Polaris hasn’t always been the North Star in the Sky. As the Earth rotates, it also wobbles a bit on its axis. This wobble shifts the location of the celestial north pole over the course of a 26,000 year span. This happens similar to how a top wobbles while it spins.
Polaris will continue to draw closer to the true celestial north pole for another 80 years before slowly drifting away. In about 2000 years, residents of Earth will use the star Errai in the constellation Cepheus as the North Star. Five thousand years ago, Thuban in Draco served as the North Star. In 12,000 years, the pole will point to Vega in Lyra.
What About A South Star?
Logic would dictate that if there’s a North Star, surely there must be something in the Southern Hemisphere that people can use to identify true south. Unfortunately, there’s no star quite bright enough to fit the bill as Polaris does in the north.
The south celestial pole is located in the constellation Octans, the Octant, but the closest star, Sigma Octantis, is barely visible even on a clear night. This makes it unsuitable as a reference point or for the purposes of navigation.
The best way to spot the south celestial pole is to use the constellation Crux. Crux, the Southern Cross, points close to the pole if you draw a line from the top to the bottom of the cross and extend that line out into space. After covering a distance in the sky four and a half times the length of the Southern Cross, you’ll reach a point approximately five degrees from the pole.
Having an easily recognizable North Star has been a blessing for those navigating at sea or hiking through the wilderness for a long time. Fortunately, the supergiant star will be available for at least a few more centuries to continue serving as a guide.
If you’re an astrophotographer in the Northern Hemisphere, the North Star may have other significance as well. It’s the perfect focal point for those amazing time-lapse photos that show the cosmos seemingly revolving around one point. Now that you know how to locate the North Star, you can try it for yourself!