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  Image: Geographic Location Direction Photo #: ISS027-E-12224 Date: Apr. 2011
Geographic Region: BOLIVIA

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  Sunset over Western South America

Astronauts on board the International Space Station see, on average, sixteen sunrises and sunsets during a 24-hour orbital period. Each changeover between day and night on the ground is marked by the terminator, or line separating the sunlit side of the Earth from the side in darkness. While the terminator is conceptualized as a hard boundary--and is frequently presented as such in graphics and visualizations--in reality the boundary between light and dark is diffuse due to 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 astronaut photograph trending across the image from lower left to upper right. This panoramic view across central South America, looking towards the northeast, was acquired at approximately 7:37 PM local time. Layers of the Earth's atmosphere, colored bright white to deep blue, are visible extending across the horizon (or limb). The highest cloud tops have a reddish glow from the direct light of the setting Sun while lower clouds are in twilight. The Salar de Coipasa, a large salt lake in Bolivia, is dimly visible on the night side of the terminator. The salar provides a geographic reference point that allows the location and viewing orientation of the image to be determined.
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Images: All Available Images Low-Resolution 76k
Mission: ISS027  
Roll - Frame: E - 12224
Geographical Name: BOLIVIA  
Center Lat x Lon: 14.5S x 61W
Film Exposure:   N=Normal exposure, U=Under exposed, O=Over exposed, F=out of Focus
Percentage of Cloud Cover-CLDP: 10
Camera: N2
Camera Tilt: HO   LO=Low Oblique, HO=High Oblique, NV=Near Vertical
Camera Focal Length: 800  
Nadir to Photo Center Direction: NW   The direction from the nadir to the center point, N=North, S=South, E=East, W=West
Stereo?:   Y=Yes there is an adjacent picture of the same area, N=No there isn't
Orbit Number: 3009  
Date: 20110409   YYYYMMDD
Time: 131941   GMT HHMMSS
Nadir Lat: 24.7S  
Latitude of suborbital point of spacecraft
Nadir Lon: 43W  
Longitude of suborbital point of spacecraft
Sun Azimuth: 38   Clockwise angle in degrees from north to the sun measured at the nadir point
Space Craft Altitude: 191   nautical miles
Sun Elevation: 51   Angle in degrees between the horizon and the sun, measured at the nadir point
Land Views: SALAR  
Water Views: LAKE  
Atmosphere Views: LIMB  
Man Made Views:  
City Views:  
Photo is not associated with any sequences

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