Series of ZSDs
Hello friends,
Recently my nice Devayani (real name hidden for the sake of
privacy) helped me create a blog and write short scientific stories for the
benefit of people. So I have chosen to say something about the series of ZSDs –
that is the series of Zero Shadow Days. Let me tell, first, the science behind
it.
Every school pupil knows from the Geography Teacher that Sun
travels from the tropic of Capricorn to tropic of Cancer from Winter Solstice
to Summer Solstice. Then it reverses its journey from Summer Solstice to Winter
solstice in the next six months. Therefore on every city, town, village between
two tropics people can see that moment of Zero Shadow Days on every place for
two days, except the places which are situate on the said tropics.
The moment of Zero Shadow happens when Sun is exactly at the
local zenith of the place. Any graduate can use advanced / modern books,
techniques, to determine the exact time, day of ZSD. However, I am using Datey
Panchang (Astronomical Ephemeries and Almanacs) which can clarify at least the
conceptual part of ZSDs. This is why I am using it for many years.
It (Datey Panchang) shows daily motion of Sun Moon Earth
etc. and various details like Kranti (which correspondence to the latitude of a
place. If on a particular day suppose Sun’s Kranti (Dec.) are same then the
people of the place can watch ZSD, momentarily
NO shadow when the Sun is at the local zenith.
In India, the southern-most city is Kannyakumari, Latitude =
8^degree and Sun’s Declination = 8 degree sand so Kannayakumari’s people will
observe ZSD on 10th April. To observe the Zero Shadow, friends can
make a circle of about 10 people and watch the shadow of the person in front of
you – that is without bending. I will give the information of important towns
cities a couple of days before the ZSD. Keep watching my blog and do not forget
to make a comment.
Lastly, I find this notation, ZSD, as a misnomer because one
does not observe zero shadow throughout the day. Hence I prefer to call it: Day
of Zero Shadow Moment: D.ZSM. What do you say?
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