Photographs by astronauts on board the International Space Station and satellite imagery often contain bright patches of light that can make certain bodies of water gleam with unusual color.
According to NASA, “That gleam is caused by sunglint, an optical phenomenon that occurs when sunlight reflects off the surface of water at the same angle that a satellite sensor views it. The result is a mirror-like specular reflection of sunlight off the water and back at the satellite sensor or astronaut.
“If bodies of water were perfectly smooth, a sequence of nearly perfect reflections of the Sun would appear in a line along the track of the satellite’s orbit. In reality, water surfaces are irregular and often in motion due to waves and currents, so the sunlight gets scattered in many directions and leaves blurry streaks of light in the swaths of satellite data.”
In the beautiful image above, you can see that sunlight is reflected off of the Atlantic along the coast of South America. This image was taken by ESA astronaut Samantha Cristoforetti and is credited to ESA and NASA.