The North Star is a star visible to the naked eye. In the night sky, it's the closest star to Earth's axis of rotation, but it's also the closest to the North Pole, hence its name. If you want to know how to find it and other even more interesting aspects, keep reading this article.
How to find the North Star?
The North Star is located in the constellation Ursa Minor and is its brightest star. This constellation is visible year-round in the Northern Hemisphere. However, due to the precession of the equinoxes, the celestial poles shift relative to the stars orbiting the ecliptic pole, which is why the North Star in each hemisphere is not the same throughout the years.
Due to this, it is very difficult to locate this group of stars in the celestial vault, making it difficult to find the polar star. A method that is traditionally used is to locate the Big Dipper and from it it is possible to more easily locate the Little Dipper and, within it, the Pole Star. The Big Dipper also receives the name of the car, due to the silhouette formed by its 7 main stars, included in the other stars that make up the figure of a bear.
When the Big Dipper has been located, what must be done is to draw an imaginary line between the two stars that are on the side of the car and extend it five times. At the other end of that line is the pole star, inside the constellation Ursa Minor, which also has the shape of a dipper.
If we can locate the North Star, we will be observing true north, and from there, we can determine the other cardinal directions. To learn more about the importance of this star in navigation, you can consult our article on constellations.
Nowadays
Today, the North Star in the Northern Hemisphere is α Ursae Minoris, located in the tail of Ursa Minor. It is also known as Polaris or Cynosura because it is closest to the North Pole, differing from it by less than one degree. It will continue to get closer, and it is expected that by the year 2100 the divergence will not exceed 28 arcminutes. After that, the North Pole is expected to move away from it, and it will not be the North Star again for approximately 25.780 years.
Past
About 4800 years ago, the star that was closest to the north celestial pole, that is, the one that could have been called the polar star of that time, was Thuban (α Draconis), whose magnitude of brightness is 3,6 and which was just 10' from the celestial pole. Today it is 50'. Thuban was known in China and Egypt, in fact, it was identified by ancient Chinese astronomers, inscribing it in yearbooks from the time of Emperor Huang Di, who reigned in 2700 BC.
But the celestial pole moved between α Ursae Minoris and α Draconis. At that time, Chiron's globe was created, the oldest known, coinciding with the time of the Argonauts' expedition, 1200 BC. It was from that moment on that the pole began to move closer to what is now the North Star.
At the beginning of our era, there was no bright star to indicate the location of the pole. Around the year 800, it was moved from a small double star in the constellation Camelopardalis, the Giraffe. To learn more about the history of stars, I recommend reading our article on the history of stars.
In the future
The current polar star, with a brightness magnitude of 2, is one of the brightest found on the path that passes through the pole and for this reason it has been called the polar star for more than a thousand years. And it will have it until about the year 3500, at which time the celestial transit of the pole will pass near a star of third magnitude called Errai or Alrai (γ Cephei).
In the year 6000 the pole will pass close to two stars classified as magnitude 3, Alfirk (β Cephei) and ι Cephei; in the year 7400 it will be close to the bright star of magnitude 1, Sadr (γ Cygni), and in the year 13 the North Star will be Vega (α Lyrae), because it will be observed as the brightest in the northern summer sky, and it will remain in this position for about 600 years. Vega will occupy the position of the North Star in the future, just as it did in the past, XNUMX years ago, during the Ice Age.
astronomical navigation
Because the North Star is located almost at the celestial north pole, it appears in the center of the circular paths that the other stars apparently follow, a result of the Earth's rotation.
This peculiarity decouples the observation time from the local coordinates of the polar star, converting the height above the horizon, which is expressed in degrees and minutes, to the latitude of the observer, not of the star. In order to achieve a correct measurement, the observation data must be modified, because the polar star is not located exactly at the north celestial pole, theoretically.
However, the North Star's prominent position in the sky made it an essential tool for navigation, as a simple observation allowed one to determine their course and latitude. To learn more about using stars for navigation, see our article on shooting stars.
at the south pole
σ Octantis is, to the naked eye, the closest star to the south celestial pole, but it doesn't help much, due to its low luminosity. It is more practical to observe the constellation of the Southern Cross, which roughly points to that location. If we are at the equator, it turns out that both Polaris and the Southern Cross can be seen.
Method to guide you
Do you know how to find stars? If it's nighttime and we don't have a compass or GPS to guide us, we might be able to orient ourselves using the stars, provided there are no clouds. The important thing is to know how to find the North Star (Polaris ) so we can use it for navigation.
https://www.youtube.com/watch?v=Y6ncTY42foc
This method of orientation only works if you are in the Northern Hemisphere, since the North Star (or Polaris) can only be seen from that part of the planet. Remember that Polaris points to true north, so when you find it, you should position yourself facing it. This will allow you to determine that east is to your right, west to your left, and south is behind you.
Polaris always points north and does not change location during the rotation of the Earth. This happens because it remains stationary in the universe, in an exceptional situation in relation to the other stars, located above the axis of rotation of the Earth. This means that, while the other stars revolve around us, the polar star always remains fixed in the sky.
Due to the Earth's rotational movement, which varies each year, and the immobility of Polaris, experts indicate that in about 3500 years the North Star will be Errai . If you want to learn more about this phenomenon, I suggest reading our article on double stars.
Another planets
Each planet has its own distinct pole star, due to its respective axis of rotation. Thus we have:
- Alpha Pictoris is located to the south and Omicron Draconis to the north of Mercury.
- Fi Draconis, is the closest in the south of the Planet venus.
- Delta Doradus, is located in the south of the Moon.
- Kappa Velorum at 2° south, and Sadr and Deneb, which are the two brightest stars in Cygnus, to the north of Mars.
- Delta Octantis is in the south of Saturn.
- Eta Ophiuchi in the north and 15 Orionis in the south of Uranus.
- To the north of Neptune, Gamma and Delta Cygni can be seen. Gamma Velorum is in the south.
- Pluto's north points to the constellation Delphinus.
The North Star and The Beatles
On February 5, 2008, at twelve o'clock at night, NASA broadcast the Beatles song "Across The Universe" in the direction of the North Star. They used the 70m antenna located at DSN's Madrid Deep Space Communication Complex, in Madrid, Spain. And it was done with an “X band” transmitter, providing the antenna with 18 KW.
The occasion merited it, because it was the 40th anniversary of the song, the 45th anniversary of the Deep Space Network (DSN), and the 50th anniversary of NASA. This idea came from Beatles historian Martin Lewis, who encouraged all Beatles fans to play the song at the same time they sent it to the star. This is the second time a piece of music has been intentionally broadcast into outer space and it was with the approval of Paul McCartney, Yoko Ono, and Apple Records.
We hope you found this reading interesting and that it has given you the knowledge you need to identify the North Star.
