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Sunset from above

Sunset seen from space

Sunset from space. This photo was taken by an astronaut aboard the International Space Station.

ASTRONAUTS ABOARD the International Space Station experience, on average, 16 sunrises and sunsets during each 24-hour orbital period (as an orbit takes only approximately 90 minutes).

Each changeover between day and night is marked by the ‘terminator’, the dividing line on Earth’s surface separating the sunlit side from the darkness.

While the terminator is often conceptualised as a hard boundary—and is frequently presented as such in graphics and visualisations—in reality the edge of light and dark is blurred due to the scattering of light by the Earth’s atmosphere.

On the ground, we experience this zone of diffuse lighting as dusk or twilight—although the Sun is no longer visible, some illumination is still present due to light scattering over the local horizon.

View from orbit of the Salar de Coipasa salt lake

A contrast-enhanced view shows details on the ground, including the Salar de Coipasa salt lake in Bolivia.

The terminator is visible in this panoramic view across central South America, looking towards the northeast. An astronaut took the photo at approximately 7:37pm local time.

Layers of the Earth’s atmosphere, coloured from bright white to deep blue, are visible on the horizon (or limb). The highest cloud tops have a reddish glow as they pick up direct light from 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 for determining the location and viewing orientation of the image.

Astronaut photograph provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Centre. Text adapted from information issued by William L. Stefanov, NASA-JSC.

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Sunset in space

An edge-on image of Earth's atmosphere

An edge-on image of Earth's atmosphere, taken by an astronaut aboard the International Space Station, reveals different layers and clouds.

  • Edge-on view of Earth’s atmosphere
  • Atmospheric layers, clouds visible
  • Astronauts see 16 sunsets and sunrises per day!

This spectacular image of sunset over the Indian Ocean was taken by astronauts aboard the International Space Station (ISS).

The image presents an edge-on, or limb view, of the Earth’s atmosphere as seen from orbit.

The Earth’s curvature is visible along the horizon line, or limb, that extends across the image from centre left to lower right. Above the darkened surface of the Earth, a brilliant sequence of colours roughly denotes several layers of the atmosphere.

Deep oranges and yellows appear in the troposphere, which extends from the Earth’s surface to 6–20 km high. This layer contains over 80 percent of the mass of the atmosphere and almost all of the water vapour, clouds, and precipitation. Several dark cloud layers are visible within this layer.

Variations in the colours are due mainly to varying concentrations of either clouds or aerosols (airborne particles or droplets).

See the full-size image here (new window).

The pink to white region above the clouds appears to be the stratosphere; this atmospheric layer generally has few or no clouds, and it extends up to approximately 50 km above the Earth’s surface.

Above the stratosphere, blue layers mark the upper atmosphere (including the mesosphere, thermosphere, ionosphere, and exosphere), as it gradually fades into the blackness of outer space.

The ISS was located over the southern Indian Ocean when this picture was taken, with the astronaut looking towards the west. Astronauts aboard the ISS see 16 sunrises and sunsets per day due to their high orbital velocity (greater than 28,000 km per hour).

The multiple chances for photography are fortunate because at that speed, each sunrise or sunset only lasts a few seconds!

Astronaut photograph provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Centre. Caption adapted from information issued by William L. Stefanov, NASA-JSC.