Every Diwali, we try to light up everything around us. Homes and buildings are covered with lamps, with the market’s decorations looking like a newlywed bride. Yet, there is something ironic about this celebration of light. The brighter our cities become, the tougher it is to see the stars. A child growing up in a large city may never see the Milky Way stretching across the night sky. The stars have not gone anywhere. We have simply surrounded ourselves with so much artificial light that their faint glow is lost. What earlier generations could see from their rooftops has become something many people must travel miles to experience.

There is a scientific reason for this. Light from buildings, street lamps and advertisements spreads into the atmosphere, making the sky appear brighter. Against that bright background, faint stars become almost impossible to distinguish. A study published in Science in 2023 found that the night sky had been getting brighter at a striking rate, making stars increasingly difficult to see with the naked eye.