Science

Basic skills of stargazing for navigation and time telling

Since time immemorial we have looked up to the stars and sought direction – sometimes with scientific rigor and sometimes with superstitions.

When the golden sunset and the twilight hit the sky ablaze into reddish hues of gold, the sky darkened into the darkness filled with a billion suns illuminating every inch. And amidst that darkness, we found our guiding lights – the stars in the sky!

 

Ancient seafarers: Navigation in an age without a GPS or compass

Of all the stars in the sky which rise in the east and set in the west, there is one star that doesn’t move from its position as long as you set your course along the same latitude of the earth. Indians called it the Dhruv tara. Astronomers call it the Polaris or the North Star. 

 

Marking some fixed points of the sky: How it works

The north star’s inclination from the ground, if measured with a sextant can give a nearly accurate idea of which latitude you’re standing on. The more you move up north of the planet, towards the pole, the star gets higher and higher up in the sky – till you’re at the north pole and the star is directly over your head.

As you move towards the equator once more the star moves towards the horizon till you cross over to the southern hemisphere of the planet from where this star will no longer be visible. So how do you navigate then?

 

Navigation with all of the stars: Navigating with constellation and star trailing

Once you cross over to the southern hemisphere, you might not be able to see the pole star but there is a constellation that can guide you on the seas. Just as you have Polaris in the north, you’ve got the constellation of crux in the south. 

The crux is a constellation that is uniquely visible from the southern hemisphere. It has got the shape of a cross and spans a small part of the southern sky. 

 

Some basic concepts of Celestial Sphere: the use of sky maps

The point of the sky overhead is called the zenith. The point below your feet, nadir. The horizon is at the zero degree and accordingly, the sky and its angles are set.

One can use a sky map to navigate. All you have to do is search for the correct latitude and season. After that use a little intuition and try to match up with the sky. And just like that as long as you can find yourself under a billion suns, you’ll always find your way.

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