See a sunset over Western South America as the astronauts do: #ISS @NASA @NASA_EO
Astronauts onboard the International Space Station see, on average, 16 sunrises and sunsets during a 24-hour orbital period. Each changeover between day and night is marked by the terminator, a line on Earth's surface separating the sunlit side from the darkness. While the terminator is often conceptualized as a hard boundary—and is frequently presented as such in graphics and visualizations —in reality the edge of light and dark is diffuse due to the scattering of light by the Earth’s atmosphere. This zone of diffuse lighting is experienced as dusk or twilight on the ground; while the Sun is no longer visible, some illumination is still present due to light scattering over the local horizon. The terminator is visible in this panoramic view across central South America, looking towards the northeast. An astronaut shot the photo at approximately 7:37 p.m. local time. Layers...