Why is the sea blue: A question that is worth a Nobel Prize

Have you ever looked at the sea and wondered, “Why is it blue?” This simple question is very special to India. It is linked to 28 February, the day India celebrates National Science Day.

A trip to europe

A great Indian scientist named C. V. Raman loved asking questions about nature. At first, he worked in the Indian Finance Service, but his heart was in science. Later, he became a Physics professor at the University of Calcutta.

In 1921, Raman travelled to Europe for a science meeting at Oxford. During this journey, he crossed the Mediterranean Sea, the Red Sea, and the Arabian Sea. He carried a small prism in his pocket and kept observing the colour of the sea. And he noticed something strange.

What people believed earlier?

Before Raman, Lord Rayleigh explained the blue sky. Rayleigh suggested that the sea appears blue because it reflects the sky’s colour. He explained that sunlight is a bundle of colours, including shades of blue and red. When sunlight enters Earth’s atmosphere, it collides with tiny air molecules, nitrogen, and oxygen. Colours, like blue and violet, scatter in all directions, while colours like red and orange mostly travel straight ahead. Blue light scatters everywhere, filling the sky, which is why the sky appears blue. However, in the evening, the light travels a longer path through the air before reaching your eyes. During this journey, blue and violet light scatter again and again, and get scattered far from your location. The colours, red, orange, and yellow, scatter much less, so they keep moving forward and finally reach your eyes.

What did raman notice?

Raman discovered that the colour of sea is independent of the sky’s colour and follows the same theory that happens in the sky. He did not stop there. His research continued…

A great discovery

While studying how light scatters, Raman made a surprising discovery in 1928. He found that when light scatters, it can change its colour slightly. This new effect was later called the Raman Effect. This discovery was made on 28 February 1928. Because of this, Raman won the Nobel Prize in Science in 1930.

National Science Day

To remember this great discovery and to inspire students to love science, India celebrates National Science Day every year on 28 February. All this began with a simple question:“Why is the sea blue?” Science starts with curiosity, just as  Raman showed us.