If you’re wondering what can Polaris be used for, you’re not alone. The northern star of the constellation is one of our nearest neighbors. Polaris is part of a binary system, and two of its stars, Polaris A and Polaris B, were once even closer to us. But during the early twentieth century, these stars separated and merged into a single star, which makes it easy to observe the star from Earth.
You can locate Polaris from anywhere in the Northern Hemisphere by looking up into the night sky. The constellation lies one degree off of Earth’s axis, so it doesn’t move very much in the night sky. Other visible stars trace a larger circle around Polaris than they do. This makes Polaris useful for determining your latitude. In the past, travelers relied on this star to guide them as they traveled.
Its brightness varies between magnitudes 1.86 and 2.13. It had more than 0.1 magnitude before Ptolemy observed it in the early fifth century. The brightness of Polaris fluctuated gradually until 1966 when it dramatically decreased to 0.05 magnitude. Since then, it has fluctuated in brightness, staying close to the 1966 magnitude. However, in 2008, a paper reported that Polaris had been increasing in brightness.
When navigating in the northern hemisphere, sailors can use the Polaris asterism to find their North Star. This star lies on the other side of the Big Dipper, so it will always be higher in the sky than the Big Dipper. When navigating at sea, the line you draw from the middle of the wider V in Cassiopeia will help you locate Polaris. Once you’ve found it, drop your gaze to the horizon directly beneath Polaris. Next, take a look at the Southern Cross, a constellation consisting of Gacrux and Acrux.
Its name, stella polaris, came from the Latin word “polar star.” The star was in the middle of the northern hemisphere during the Renaissance. The star was named Polaris by Gemma Frisius, a Dutch physician, geographer, and mathematician. In 1547, she named it “Polaris” and determined that it was about 3 deg.7′ from the north celestial pole.
The north celestial pole is a projection of Earth’s rotation axis onto the sky. Polaris lies within 3/4 degree of the north celestial pole and appears stationary to observers in the northern hemisphere. Although Polaris is positioned in the middle of this pole, it moves around it during the sidereal day, which is four minutes shorter than the solar day. This proximity makes it an important navigation star.
The north pole of some planets align with stars in Draco the Dragon, and the pole star of the Earth is called the North Celestial Pole. The pole star moves through space every 26,000 years, marking the North Celestial Pole in precise positions. 5000 years ago, Polaris pointed towards the star Thuban, now it points to Draco the Dragon. It will point to Vega in 13,000 years.
Using this information, astronomers can determine the distance to stars. Polaris is near the north celestial pole, but its relative brightness makes it difficult for ground-based telescopes to point to it. Several telescopes can only point to a few degrees closer than the north celestial pole. HIPPARCOS is another instrument that measures distances. With this new tool, astronomers can determine distances to distant objects with great accuracy.