POLARIS

Introduction

Polaris. For centuries, it has beenused by navigators and explorers to find their way as an astrological compass. For millennia, it has been the subject of ancient and significant mythology. For decades, it has been studied and researched by astronomers.

So what is it, really? In this virtual tourof outer space, we will attempt to answer this question, and unveil the secrets of one of the most famous and brightest stars in the night sky.

Where?

Polaris can be found in the distant Ursa Minorconstellation, and is located 434 light yearsfrom our own solar system. To put it inmore comprehensible terms; it is more than four quadrillion kilometers away. The reasonPolaris is of such important note is becauseit is located only 0.7 degrees off our NorthPole. Although there are stars closer than thatto our North Pole, Polaris is the brightest.

Because of this vast difference in distances,Polaris is not gravitationally tied with our own solar system. In fact, if Polaris was closer,it’s much more likely that we would be the onesorbiting it; a study in 2000 showed that Polariswas 46 times the size of our sun. It should,however, be noted that Polaris is what is knownas a Cepheid Variable star – this means thatits luminosity can fluctuate over time.

What?

Polaris is a yellow-white supergiant,while our own sun is considered a yellow dwarf. It’s composed almost entirely of hydrogen and helium, like all stars.

Compared to our own sun, Polaris is 1500 kelvins warmer, at around 7200K,7.5 times heavier, and is 2200 times more luminous.

Polaris compared to many other stars, including our sun.

Although Polaris is incredibly brilliant and overshadowing, it isn’t the onlything up there. Polaris A, the largest and most famous star in the Polaris solar system, is orbited by two other stars, the closer one being Polaris AB and the farther one being Polaris B. Polaris AB, the smallest, is a mere 18 AU away from Polaris – this means that the closest star from Polaris is only as far as Uranus is from our sun!

Polaris B is about 2000 AU from Polaris A. It’s larger than Polaris AB, but still not nearly as large as A. There are no identified planets in the Polaris solar system; only stars.

What else?

History of Human Study

Polaris has been used as a navigational tool since at least the time of the ancient Greeks. Before that, however, Polaris was not always the North Star.

During the time of the ancient Egyptians, Thuban was a more accurate representationof the North than Polaris was – this is becausethe axis of the Earth shifts in 26,000 year cycles,causing the poles to realign. In another 12,000years, Vega will become the new North Star, andPolaris will have lost its place. 26,000 years fromnow, Polaris will have re-taken its place as the North Star.

Ursa Minor, the constellation where Polaris is located, has also been the subject of many myths. The Greeks believed that it was formed when a mother and her son, who had both been transformed into bears, were banished into the sky. Ursa Minor is one of those bears, while Ursa Major is the other.

If you’re looking at Polaris, point one arm at it and point the other arm at the horizon. The degrees that the angle of your arms make is close to the latitude of your current location on Earth.

Polaris is the brightest star in the Little Dipper.

Earth isn’t the only planet with a pole star; Mars has one, as well, but it isn’t bright enough to be useful.

Contrary to popular belief, Polaris isn’t the brightest star in the night sky, it’s just the brightest star in the Ursa Minor constellation. Out of all the stars we can see, Polaris is the 40th brightest.

Fun Facts