Atmospheric refraction is the bending of light as it passes through different layers of the Earth's atmosphere. This phenomenon occurs because the atmosphere is made up of various gases with varying densities, which causes light to change speed and direction. As a result, objects such as the Sun or Moon can appear higher in the sky than they actually are. This bending of light also affects how we perceive distant objects. For example, when looking at a sunset, the Sun may appear flattened or distorted due to the layers of air it passes through. Atmospheric refraction is responsible for various optical effects, including the twinkling of stars and the appearance of mirages.