The star Polaris is a fixed point in the northern night sky. Many cultures across the northern hemisphere have a deep relationship to Polaris. Norse mythology teaches us that it is the end of a spike around which the sky rotates, and Mongolian legend explains it as the peg that holds the world together. In 2008, NASA transmitted the song “Across the Universe” to the North Star. However, what is Polaris’ significance?
Using Polaris to locate your position in the sky has been around for centuries. It is the closest star to the North Celestial Pole, lying in line with the northern axis of rotation. For hypothetical observers at the North Pole, Polaris would be directly overhead. In addition, it never rises or sets, making it appear motionless in the sky. In this way, Polaris is a useful navigational tool. In addition to that, astrometry and other applications depend on its location.
Although the North Star is not the brightest star in the sky, it can still be seen at night, even in a city. This is because it is located in the direction of true north, not magnetic north. Moreover, Polaris lies more or less directly above the north pole of the Earth, making it a highly visible star at night. Because it is so close to Earth’s north pole, Polaris has great value as a navigation star.
The brightness of Polaris varies between magnitudes 1.86 and 2.13. Before 1963, it had a brightness of 0.1 magnitude, but afterward it dropped to just 0.05%. The brightness of Polaris varies unpredictably since then, staying relatively close to the magnitude of 1966. However, recent observations show that Polaris may be 2.5 times brighter today than it was when Ptolemy first observed it. Despite this, researchers are still unsure about the cause of the star’s brightness fluctuations.
As the distance to Polaris changes, astronomers can more accurately calculate its brightness. The new distance of Polaris fixes a long-standing uncertainty regarding its distance from Earth. The improved distance makes it possible to calibrate the period-luminosity relationship of Polaris and more accurately determine the star’s luminosity. It also confirms the importance of Cepheid stars. And, as we said earlier, Polaris is a Cepheid.
As you move southwards, Polaris becomes lower in the sky. It will disappear below the equator by the year 2100, making it easier to view. Until that time, however, it will continue to be the North Star. The closest approach to the North Pole will occur on March 24, 2100. It will be 27’09” away from the north celestial pole at that time, and less than the angular diameter of the moon’s farthest distance from Earth. If you are not in the northern hemisphere, you will be unable to observe the star for at least 2,000 years.
To find Polaris, locate the Big Dipper. The Big Dipper has two bright stars at the end, known as the Pointer Stars. These two stars point to the North Star. If you trace an imaginary line between the Pointer Stars and Polaris, you will see that Polaris is about five times farther away than the two Pointer Stars. You can also find Polaris by finding the seven stars of the Big Dipper, which forms a small bowl with a long handle.
In addition to the North Pole, the South Pole has a bright star called Gamma Chamaeleontis. In a few thousand years, the south pole will point toward Gamma Chamaeleontis, Carina, Vela, and Canopus. At that time, the North Pole will point to Vega. Its position will continue to change as the earth rotates. You will need to adjust your course accordingly.
Another way to find Polaris is to observe the stars that form the Big Dipper. The brightest of these stars is Polaris, while the Pointer Stars always point toward it. The Big Dipper will go around Polaris on its axis every 23 hours, so it’s important to know the position of these stars. A meteorologist recommends locating the stars known as “Pointers” instead. These stars form the wall of a bowl at the farthest end of the Big Dipper’s handle. This works even when the Big Dipper is “upside down.”
The brightest star in Ursa Minor, Polaris is a triple star system. It has a yellow supergiant star, Polaris Aa, and two smaller companions, Polaris B, which are both white. The three stars in Polaris are orbiting one another and are 2,500 times brighter than the Sun. Each of the three stars has critical physical parameters. So, when you see Polaris, remember to pay attention.