Your shadow,not always with you

The sun appears twice a year exactly overhead for those who live between the Tropic of Cancer and the Tropic of Capricorn. Arvind Paranjype from the public outreach programme of Inter University Centre for Astronomy and Astrophysics (IUCAA),said,“The same effect can be studied very well by looking into a well. Not every day is the bottom of a well illuminated uniformly everywhere. But on this day the bottom of the well has sun-rays reaching everywhere,though just for short while.”

The phenomenon occurs due to the movement of the sun northwarsd and southward of the equator once every year,called the migration of the sun.

In India,the movement is known as Uttarayan and Dakshinayan. Now the sun is on its Uttarayan (northward) journey,and over the next few days zero shadow will occur in Mumbai on May 16,Nashik on May 21 and Nagpur on May 27. After the sun reaches the Tropic of Cancer on June 21,it will start travelling southwards (Dakshinayan). “Again we will have zero shadow days in the reverse order,Nagpur on July 18,Nashik on July 24,and Mumbai on July 29. In Pune it will be on July 31,” said Paranjype. Akshay Parag,an astronomy enthusiast and schoolteacher,said,“It was one of the best days to introduce students to concepts of shadows and movement of the sun. We used a transparent bottle half-filled with water without a cap. When the sun was overhead,students saw the image of the bottle rim at the exact centre of the bottle at the bottom.”