Find directions with Shadows

The Sun rises in the East and sets in the West. But every day the Sun does not rise at the same location. How can we find a true East then ?

With the help of a needle and pins, we can decide directions at any given location.

It's 10 AM local time in Pune India. 18.5204° N, 73.8567° E

Let us place a needle in an upright position on this bunch of corrugated sheets. It's important to ensure that ground is leveled as well.

We will place another pin at the tip of the shadow.

Same can be repeated twice with a gap of 30 mins.

Now let us remove pins and join all the three points.

This end of the line is pointing towards the East direction while this one towards West.

With some simple geometry, let us draw perpendicular to this line.

Can we guess which direction this end is pointing to ?

Is this method 100 percent accurate ? Not really.

As the Declination of the SUN changes during the day, this may not be the exact East West line.

Only on two solistitial days, December 22 and June 22, it represents the exact East - West Line. On these days change in declination during the day is negligible.

It also depends what time of the day you take the reading.

There are more accurate methods described in the ancient astronomy related Text Surya Siddhant.

We will go through these methods in the next video.

Thank you.

#astronomy
#directionsense
#directions

[Learning_videos]

I understand easily sir
Thank you
Nice 👍 video sir