Sir: On February 22, National Aeronautics and Space Administration (NASA) has discovered seven Earth-like planets, orbiting a star 40 light years (235 trillion miles) away from the Earth. It is believed that three of these planets have water on their surface. Although in the past few years, thousands of planets have been discovered, but the planet where water and oxygen could exist, has not been found yet. Discovering Earth-like planets is believed to be the initial step towards finding other life in the universe. Announcing the discovery, NASA officials said this “gives us a hint that finding a second Earth is not just a matter of if but when”. This is the colossal accomplishment by the NASA, the more Earth-like planets, astronomers find in the galaxy, the more they will estimate of presence of natural life on these planets. MUHAMMAD MUKHTIAR SHAR Islamabad