Question

How doesth pole star help on identification of maps?

Answer 1

The Earth rotates on its axis - an imaginary line running through the Earth. If we follow this axis out into space from the northern hemisphere on Earth, it points towards a particular star in the sky. We call that star the "North Star" since it sits in the direction that the spin axis from the northern hemisphere of Earth. At present, the star known as Polaris is the North Star. A pole star is aligned with the Earth's axis of rotation and the apparent position is above the celestial poles, and which lies approximately directly overhead when viewed from the Earth's North Pole or South Pole.

So at any hour of the night, at any time of the year you can readily find Polaris and it is always found in a due northerly direction. If you were at the North Pole, the North Star would be directly overhead. The North Star has been used for navigation - especially ships at sea - since ancient times, both to find the direction of north - and so the other directions - and to determine the latitude. (Latitude of a given location is the measured angle of the North Star over the horizon.Like - from Bengaluru, the North Star can be seen ~13° above the Northern horizon and the latitude of Bengaluru is therefore ~13° North. Needless to mention, if we are on the equator or thereabouts, we cannot see the North Star because it will be on the horizon - or at 0° for us.)

As you face Polaris and stretch your arms sideways, your right hand points due east, and your left hand points due west. South is behind. (As you travel northward, Polaris climbs higher in the sky. If you go as far north as the North Pole, you’ll see Polaris directly overhead. As you travel south, Polaris drops closer to the northern horizon. If you get as far as the equator, Polaris sinks to the horizon. South of the equator, Polaris drops out of the sky.)