DAVID PARKER / SCIENCE PHOTO LIBRARY DAVID PARKER / SCIENCE PHOTO LIBRARY
Atmospheric refraction is the deviation of light from a straight line as it passes through the atmosphere due to the variation in air density as a function of altitude. Near the ground it produces mirages and can make distant objects such as the Sun to appear to shimmer or ripple, elevated or lowered, stretched or in this case, squashed. It causes astronomical objects to appear higher in the sky than they are in reality. For example in visible light, blue is more affected than red. Whenever possible, astronomers will schedule their observations around the time of culmination of an object when it is highest in the sky. Likewise sailors will never shoot a star which is not at least 20° or more above the horizon. Illustration from 'The Heavens' by Amedee Guillemin, Publ. Richard Bentley 1878.
Model release not required. Property release not required.