AKASHAM LO AKSHARALU YELA RASTHARU?/ HOW LETTERS WILL BE WRITTEN IN THE SKY?

With the help of aeroplanes we can write the letters,words in the sky.This is known as " sky writing ". This is invented by John c sevage.
First time in the England they wrote " daily mail " in the sky, and in the New York they wrote " hello sa".For this sky writing they use paraffin oil that mixed in the smoke of aeroplane comes from its back side.