Observing Polaris is an important skill if you plan to sail on the seas. The North Star, also called Polaris, is the north celestial pole. As the earth spins, its position in the sky changes with the axis. In fact, the North Pole isn’t a fixed point, and the positions of the stars and planets have changed significantly over the centuries. However, you can still make use of Polaris to navigate your canoe.
The constellation Ursa Minor contains the star Polaris. In the constellation, you can spot this star by looking up the “Little Dipper.” The Little Dipper has a group of stars that form a long handle. The star Polaris is located near the end of the handle. The Little Dipper is not very bright. The easiest way to find Polaris is to locate the seven stars of the Big Dipper in Ursa Major. Those stars point to the North Star.
Unlike a magnetic compass, Polaris does not move and is a useful tool for finding the northernmost part of a country. The angle between the north horizon and Polaris determines latitude. Many ancient travelers resorted to this star as a means of finding their position. But nowadays, it is often overlooked. It is even more important than the magnetic compass. And it is used by sailor and sea-farers to navigate the world.
Ancient Egyptian astronomers used the star as a guide in the Old Kingdom. They symbolically represented the North Star with a female hippopotamus. Ptolemy was the first person to discover Polaris. During this period, the Earth’s axis of rotation was aligned with Polaris and thus, Polaris would be overhead for northern observers. This star did not rise nor set, making it useful for navigation.
The three stars in the Polaris triple star system are gravitationally bound. The main star, Polaris Aa, is 5.4 solar masses and spectral type lb. It is orbiting at a distance of 2.400 AU, or around 240 billion miles / 390 billion kilometers from Earth. This distance is close enough to make the star visible through even modest telescopes. The two stars are remarkably close, and can be seen in an eight-inch, three-inch telescope.
The relative position of Polaris in the sky depends on where you are, and the location of the pole. For example, the north celestial pole will be at 90 degrees from the equator, while Houston is 30 degrees away from the pole. Observers in the southern hemisphere will have to wait two thousand years before they can see the pole star. Therefore, you must use a rule of thumb or a table to find Polaris in the sky.
Scientists also found that Polaris has been changing in brightness for many centuries. Since Ptolemy’s observations, it has been around 2.5 times brighter than it was in Ptolemy’s time. As the star continues to change, its brightness also varies unpredictably, but it has remained close to the same magnitude in the last 50 years. In fact, a recent paper showed that Polaris was actually brighter than it was during Ptolemy’s time.
Despite the North Star not being the brightest star in the sky, it is easy to spot, even from the middle of a city. It sits more or less directly above the north pole of the Earth, and is a reliable gauge of north. However, Polaris was not always a reliable guide for navigation, and Earth’s axis shifts over time. To make this determination, you must be familiar with the planet’s rotational axis.
In the Northern Hemisphere, Polaris is a prominent star. In fact, it is the brightest star in the constellation Ursa Minor, which is also called the Little Dipper. It occupies a special place in the night sky. This star lies near the North Celestial Pole, which makes the stars in the northern sky appear to rotate around it. This makes Polaris the northern star. As such, it is a key object to be aware of.
In the night sky, look up and observe the constellation’s brightest star, Polaris. Its three companion stars are separated by about 2,400 astronomical units. The two smaller stars, Polaris A and Polaris B, are a part of the constellation’s triple star system. The stars have different brightness, but both are known to be Cepheid variables. It is also used to measure the distances of galaxies and the expansion rate of the universe.