One of the important parts of Navigation is the ability to find the direction. Finding the direction is not a difficult task if we have access to modern instruments like compass and GPS. Sometimes, these instruments are not being accessible to us then we need to know this survival skill of finding direction with the help of stars. In ancient time, sailors were able to reach exact islands without any mistake by using position of stars.
Although there are lots of ways and tips to use stars in the night sky but one of the basic tip is about finding the North direction. You can easily locate North direction by finding the Pole Star. After finding the North direction, all other directions can be easily found. But for that you need to know about Pole Star and its location. Pole star is also known as Polaris.
What is Polaris?
Whenever you looked at the night sky, did you find the same position of all the stars? No, the position of all the stars depends upon the time of observation. In other words, all the stars rise from the East and moves slowly towards the West. So if you will observe any star after sometime say 1 hour then you will observe that it has moved towards West by small amount. In this way, the whole night sky rotates from East to West. But the point of rotation or you can say the point along the axis of rotation remains fix and good news is that one star is also present at the point of rotation.
This star which is present along the axis of rotation is called the pole star or Polaris. Pole star never changes its position; the whole night sky appears to rotate around the Pole star.
How can Pole star help us in finding the direction?
The motion of night sky is apparent means actually all the stars are fixed; it is the Earth that rotates. The axis of rotation passes through the center of the Earth, North and South poles. Polaris is the star present along the axis of rotation of the Earth and it appears directly above the North Pole. Due to presence along the axis of rotation, Pole star appears to be fixed and location of Pole Star is the direct indication of North direction. Polaris can help us in finding North Pole only in the Northern Hemisphere.
How to find Polaris?
Many people think that the Pole star is the brightest star of the sky. This is not true, Polaris is bright enough to be located easily in North but it is not brightest star. There are not too many stars in the North direction around the Pole star but you need to know an exact method to find the Pole Star.
The Pole Star can be easily located with the help of constellation Ursa Major which is also known as big dipper. Ursa Major constellation is the group of seven stars which appears like sauce pan. Three stars form the handle of pan and other four stars form the bowl. Now when you extend the line joining the last two stars on the other side of handle, you will find a star at the distance of about five times the distance between these two stars, this star is Polaris.
As the Polaris remains fixed, the Ursa Major moves around the Polaris but the extended line always meet the Polaris. The important thing is that Ursa Major should be above horizon at a certain height for this purpose. Sometimes, Ursa Major is too low in height then you need to know other method to find Polaris.
Cassiopeia is the constellation present on the other side of Polaris which appears in the form of W of M. From the Polaris it appears like M. When you will join the middle star of Cassiopeia and the third star of Ursa Major form the side of handle then the line will pass through the Polaris and you can easily find it.
After finding the North direction, other can be found easily. You have to face towards the Pole star and your right hand will indicate East and left hand will indicate west, South will be on the backside. Good thing is that the Pole star will not change its position.
How to find latitude using Polaris?
The height of Polaris above the horizon is the direct measure of the latitude of that place. For exact measurement, you need to have sextant to measure angular distance of Polaris from the horizon but for rough idea, you can use your hand. You have to stretch your hand in front of you and the width of your fist is about 10 degree. So you can get a rough idea of latitude by measuring height of Polaris from the horizon.
There are other constellations which can help you in navigation but many of these depend on seasons. For example famous Orion constellation appears during winter. But Pole Star is helpful in all the seasons.
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