An astronaut aboard the International Space Station took this photo while orbiting over the Indian Ocean. The Earth appears black in the lower half of this image, mirroring the darkness of space above. Atmospheric layers span the image, displaying a range of hues. The troposphere generally appears orange and red, the stratosphere is mostly white, and the mesosphere is shades of blue. The Moon, with a shimmering streak-like feature below it, is visible near the top atmospheric layers.
When this photograph was captured on September 4, 2024, the Moon was in the waxing crescent phase. During this phase, only a sliver of the Moon is illuminated by reflected sunlight, visible as the extra-bright white crescent on the Moon’s lower-right edge. Camera settings such as exposure, shutter speed, and aperture increased the visibility of the Moon in this image, giving the impression of a full Moon. Another photo taken just before this one offers the same field of view, but different camera settings provide an image more similar to what human eyes would see.
At the time of this photo, the Moon was positioned behind Earth’s atmosphere relative to the space station. The atmosphere acts like a lens, bending light that passes through it and toward the astronaut’s camera, causing the Moon to appear non-uniform in shape.
Bent, or refracted, light also led to another optical phenomenon in this image. Water vapor that reaches high in the atmosphere can freeze onto tiny dust particles, generating ice crystals in the mesosphere. Light refracted by these ice crystals likely formed the arc-shaped partial lunar halo visible near the Moon.
References & Resources
Astronaut photograph ISS071-E-609044 was acquired on September 4, 2024, with a Nikon Z9 digital camera using a focal length of 200 millimeters. It is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 71 crew . The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth . Caption by Elysia N. Viengkham, Amentum-JETS II Contract at NASA-JSC.
