iss071e364425 (July 16, 2024) --- Noctilucent clouds, high-altutude clouds visible during the summer months and illuminated when the sun is below Earth's horizon, are pictured from the International Space Station as it orbited 259 miles above the Pacific Ocean south of Alaska.

Noctilucent clouds illuminated when the sun is below Earth's horizon

iss073e0257194 (June 28, 2025) --- Noctilucent clouds, upper atmospheric clouds illuminated by the sun below Earth's horizon and composed of water vapor crystals that form about 50 miles in altitude during the summertime, are pictured from the International Space Station as it orbited 261 miles above the North Pacific Ocean.

Noctilucent clouds are pictured above the North Pacific Ocean

Earth Limb taken by the Expedition 17 Crew

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ISS036-E-028913 (4 Aug. 2013) --- A sunset over the Aleutian Islands, with noctilucent clouds, is featured in this image photographed by an Expedition 36 crew member on the International Space Station. The crew member took this panoramic view looking north from the Aleutian Islands when the space station was flying east at ?the top of the orbit,? the northernmost latitude reached by the orbital complex (51.6 degrees north). If the sun had been higher, the string of Aleutian Islands would have been visible in the foreground. Here the islands are on the dark side of the day-night line. From their vantage point at 222 kilometers altitude on this day, crew members were able to see as far north as the Arctic Ocean and the midnight sun. This image was taken just 20 minutes after local midnight in early August 2013. The midnight sun makes the red, diamond-shaped teardrop reflection (lower center)?perhaps a reflection within the camera lens, or from the window frame, or some item inside the ISS. Long blue-white stringers can be seen in the atmosphere above the midnight sun. These are known as noctilucent clouds (night-shining clouds). Some crew members say these wispy, rippling, iridescent clouds are the most beautiful phenomena they see from orbit. Noctilucents are thin so that they are best seen after sunset when the viewer is on the night side of the day-night line, but while these high clouds are still lit by the sun. Crews are trained in this somewhat complicated geometry?of clouds being lit from beneath, with the spacecraft in sunlight though the ground directly beneath is in darkness. Noctilucent clouds are also known as polar mesospheric clouds (PMCs) as they appear in the summer hemisphere over polar latitudes. Some data suggest that they are becoming brighter, and appearing at lower latitudes, perhaps as an effect of global warming. A comparison of noctilucent cloud formation from 2012 and 2013 has been compiled using data from NASA?s Aeronomy of Ice in the Mesosphere (AIM) shows an earlier start and an increase in the area covered by these clouds in 2013. Polar mesospheric clouds are interesting to scientists because they form much higher in the atmosphere (75-90 kilometers) compared with altitudes of normal rainclouds that form in the lowest, densest ?weather-layer? below approximately 15 kilometers. The weather layer, or troposphere, is most distinct in this image as a thin orange line along the left horizon.

Curiosity Views Twilight Clouds

NASA's Curiosity Mars rover used its left Mast Camera, or Mastcam, to capture these drifting noctilucent, or twilight, clouds on Jan. 17, 2025, the 4,426th Martian day, or sol, of the mission. The left Mastcam has a stuck color filter wheel, which is why part of the imagery appears cut off in three corners. The original recording taken by Curiosity was 16 minutes; this video has been speeded up by about 480 times (and it loops four times). The clouds at the top of the frame, including the falling white plumes, are made of carbon dioxide ice. The plumes are an estimated 37 to 50 miles (60 to 80 kilometers) above the Martian surface; they could fall as low as 31 miles (50 kilometers) above the surface before they would evaporate due to rising temperatures. In the lower half of the frame at the beginning of the video, a different set of very faint clouds is visible. These are water-ice clouds are hovering at roughly 31 miles (50 kilometers) in altitude. The brightness has been stretched to make certain colors more visible in this enhanced-color imagery. This is the fourth Mars year that twilight clouds have been observed by Curiosity; previous observations were made in 2019, 2021, and 2023. Animation available at https://photojournal.jpl.nasa.gov/catalog/PIA26519

Moon during sunset taken by the Expedition Seven crew

ISS007-E-10974 (27 July 2003) --- Photographed by an Expedition 7 crewmember onboard the International Space Station (ISS), this image shows the limb of the Earth at the bottom transitioning into the orange-colored troposphere, the lowest and most dense portion of the Earth's atmosphere. The troposphere ends abruptly at the tropopause, which appears in the image as the sharp boundary between the orange- and blue- colored atmosphere. The silvery-blue noctilucent clouds extend far above the Earth's troposphere. The sliver of the setting moon is visible at upper right.

Curiosity Navigation Cameras Spot Twilight Clouds on Sol 3072

Using the navigation cameras on its mast, NASA's Curiosity Mars rover took these images of clouds just after sunset on March 28, 2021, the 3,072nd so, or Martian day, of the mission. These noctilucent, or twilight clouds, are made of water ice; ice crystals reflect the setting sun, allowing the detail in each cloud to be seen more easily. Movie available at https://photojournal.jpl.nasa.gov/catalog/PIA24646

International Space Station (ISS)

This Expedition Seven image, taken while aboard the International Space Station (ISS), shows the limb of the Earth at the bottom transitioning into the orange-colored stratosphere, the lowest and most dense portion of the Earth's atmosphere. The troposphere ends abruptly at the tropopause, which appears in the image as the sharp boundary between the orange- and blue-colored atmosphere. The silvery blue noctilucent clouds extend far above the Earth's troposphere. The silver of the setting moon is visible at upper right.

Lunar Observation

ISS028-E-020072 (31 July 2011) --- Photographed by an Expedition 28 crew member onboard the International Space Station, this image shows the moon at center, with the limb of Earth near the bottom transitioning into the orange-colored troposphere, the lowest and most dense portion of the Earth's atmosphere. The troposphere ends abruptly at the tropopause, which appears in the image as the sharp boundary between the orange- and blue- colored atmosphere. The silvery-blue noctilucent clouds extend far above the Earth's troposphere.

Lunar Observation

ISS028-E-020073 (31 July 2011) --- Photographed by an Expedition 28 crew member onboard the International Space Station, this image shows the moon at center, with the limb of Earth near the bottom transitioning into the orange-colored troposphere, the lowest and most dense portion of the Earth's atmosphere. The troposphere ends abruptly at the tropopause, which appears in the image as the sharp boundary between the orange- and blue- colored atmosphere. The silvery-blue noctilucent clouds extend far above the Earth's troposphere.

Curiosity Navigation Cameras Spot Twilight Clouds on Sol 3075

Using the navigation cameras on its mast, NASA's Curiosity Mars rover took these images of clouds just after sunset on March 31, 2021, the 3,075th so, or Martian day, of the mission. These noctilucent, or twilight clouds, are made of water ice; ice crystals reflect the setting sun, allowing the detail in each cloud to be seen more easily. Movie available at https://photojournal.jpl.nasa.gov/catalog/PIA24645

Earth Observations taken by Expedition 34 crewmember

ISS034-E-024622 (5 Jan. 2013) --- Polar mesospheric clouds over the South Pacific Ocean are featured in this image photographed by an Expedition 34 crew member on the International Space Station. Polar mesospheric clouds—also known as noctilucent, or “night shining” clouds—are formed 76 to 85 kilometers above Earth’s surface near the mesosphere-thermosphere boundary of the atmosphere, a region known as the mesopause. At these altitudes, water vapor can freeze into clouds of ice crystals. When the sun is below the horizon such that the ground is in darkness, these high clouds may still be illuminated—lending them their ethereal, “night shining” qualities. Noctilucent clouds have been observed from all human vantage points in both the Northern and Southern Hemispheres – from the surface, in aircraft, and in orbit from the space station—and tend to be most visible during the late spring and early summer seasons. Polar mesospheric clouds also are of interest to scientists studying the atmosphere. While some scientists seek to understand their mechanisms of formation, others have identified them as potential indicators of atmospheric changes resulting from increases in greenhouse gas concentrations. This photograph was taken when the station was over the Pacific Ocean south of French Polynesia. While most polar mesospheric cloud images are taken from the orbital complex with relatively short focal length lens to maximize the field of view, this image was taken with a long lens (400 mm) allowing for additional detail of the cloud forms to be seen. Below the brightly-lit noctilucent clouds in the center of the image, the pale orange band indicates the stratosphere.

Earth Observation

ISS028-E-020276 (2 Aug. 2011) --- This photograph of polar mesospheric clouds was acquired at an altitude of just over 202 nautical miles (about 322 kilometers) in the evening hours (03:19:54 Greenwich Mean Time) on Aug. 2, 2011, as the International Space Station was passing over the English Channel. The nadir coordinates of the station were 49.1 degrees north latitude and 5.5 degrees west longitude. Polar mesospheric clouds (also known as noctilucent, or ?night-shining? clouds) are transient, upper atmospheric phenomena that are usually observed in the summer months at high latitudes (greater than 50 degrees) of both the Northern and Southern Hemispheres. They appear bright and cloudlike while in deep twilight. They are illuminated by sunlight when the lower layers of the atmosphere are in the darkness of Earth?s shadow. The horizon of Earth appears at the bottom of the image, with some layers of the lower atmosphere already illuminated by the rising sun. The higher, bluish-colored clouds look much like wispy cirrus clouds, which can be found as high as 60,000 feet (18 kilometers) in the atmosphere. However noctilucent clouds, as seen here, are observed in the mesosphere at altitudes of 250,000 to 280,000 feet (about 76 to 85 kilometers). Astronaut observations of polar mesospheric clouds over northern Europe in the summer are not uncommon.

Curiosity's Three-Frame Mosaic of Clouds

NASA's Curiosity Mars rover imaged these drifting clouds on May 17, 2019, the 2,410th Martian day, or sol, of the mission, using its black-and-white Navigation Cameras (Navcams). These are likely water-ice clouds about 19 miles (31 kilometers) above the surface. They are also "noctilucent" clouds, meaning they are so high that they are still illuminated by the Sun, even when it's night at Mars' surface. Scientists can watch when light leaves the clouds and use this information to infer their altitude. Movie available at https://photojournal.jpl.nasa.gov/catalog/PIA23243

Curiosity Sees More Clouds Over Gale Crater

NASA's Curiosity Mars rover imaged these drifting clouds on May 7, 2019, the 2,400th Martian day, or sol, of the mission, using its black-and-white Navigation Cameras (Navcams). These are likely water-ice clouds about 19 miles (31 kilometers) above the surface. They are also "noctilucent" clouds, meaning they are so high that they are still illuminated by the Sun, even when it's night at Mars' surface. Scientists can watch when light leaves the clouds and use this information to infer their altitude. Movie available at https://photojournal.jpl.nasa.gov/catalog/PIA23242

Curiosity Sees Drifting Clouds Over Gale Crater

NASA's Curiosity Mars rover imaged these drifting clouds on May 12, 2019, the 2,405th Martian day, or sol, of the mission, using its black-and-white Navigation Cameras (Navcams). These are likely water-ice clouds about 19 miles (31 kilometers) above the surface. They are also "noctilucent" clouds, meaning they are so high that they are still illuminated by the Sun, even when it's night at Mars' surface. Scientists can watch when light leaves the clouds and use this information to infer their altitude. Movie available at https://photojournal.jpl.nasa.gov/catalog/PIA23241

Buffalo, Toronto and Niagara Falls at night as seen from STS-60

STS060-06-037 (3-11 Feb 1994) --- The city lights of Buffalo and Toronto outline the shores of the east end of Lake Erie and the west end of Lake Ontario in this night scene of western New York and southern Ontario. Between the two major cities are the cities of Niagara Falls, New York and Niagara Falls, Canada, which straddle the Niagara River just north of the actual falls. This photograph was taken with a special ASA-1600 film that is normally used for night-time photography of aurora, noctilucent clouds, biomass burning, and city lights.

Curiosity Views First Martian 'Sun Rays'

NASA's Curiosity Mars rover captured these "sun rays" shining through clouds at sunset on Feb. 2, 2023, the 3,730th Martian day, or sol, of the mission. It was the first time that sun rays, also known as crepuscular rays, have been viewed so clearly on Mars. Crepuscular is taken from the Latin word for "twilight," as these rays appear near sunset or sunrise. These clouds were captured as part of a follow-on imaging campaign to study noctilucent, or "night-shining" clouds, which started in 2021. While most Martian clouds hover no more than 37 miles (60 kilometers) above the ground and are composed of water ice, these clouds appear to be higher in elevation, where it's very cold. That suggests these clouds are made of carbon dioxide, or dry ice. This scene made up of 28 individual images captured by the rover's Mast Camera, or Mastcam. The images have been processed to emphasize the highlights. https://photojournal.jpl.nasa.gov/catalog/PIA25739

Curiosity Views Feather-Shaped Iridescent Cloud

NASA's Curiosity Mars rover captured this feather-shaped iridescent cloud just after sunset on Jan. 27, 2023, the 3,724th Martian day, or sol, of the mission. Studying the colors in iridescent clouds tells scientists something about particle size within the clouds and how they grow over time. These clouds were captured as part of a follow-on imaging campaign to study noctilucent, or "night-shining" clouds, which started in 2021. While most Martian clouds hover no more than 37 miles (60 kilometers) above the ground and are composed of water ice, these clouds appear to be higher in elevation, where it's very cold. That suggests these clouds are made of carbon dioxide, or dry ice. This scene made up of 28 individual images captured by the rover's Mast Camera, or Mastcam. The images have been processed to emphasize the highlights. https://photojournal.jpl.nasa.gov/catalog/PIA25740

Earth Limb taken by the Expedition 17 Crew

ISS017-E-011632 (22 July 2008) --- Polar Mesospheric Clouds (also known as noctilucent clouds) are transient, upper atmospheric phenomena observed usually in the summer months at high latitudes (greater than 50 degrees) of both the Northern and Southern Hemispheres. They are bright and cloudlike in appearance while in deep twilight. They are illuminated by sunlight when the lower layers of the atmosphere are in the darkness of the Earth's shadow. This image was acquired at an altitude of just over 200 miles in the pre-dawn hours of July 22, 2008 as the International Space Station was passing over western Mongolia in central Asia. The dark horizon of the Earth appears below with some layers of the lower atmosphere already illuminated. The higher, bluish-colored clouds look much like wispy cirrus clouds which can be found in the troposphere as high as 60,000 feet. However noctilucent clouds, as seen here, are observed in the mesosphere at altitudes of 250,000 to 280,000 feet. Astronaut observations of Polar Mesospheric Clouds (PMC) over northern Asia in June and July are not uncommon. The Expedition 17 crew of the International Space Station acquired this image, and more, in support of research for the International Polar Year. Some researchers link increased observations of PMC to changes in global climate; PMC have been the subject of extensive observation and research from space by the Swedish satellite Odin launched in 2001 and more recently by NASA's Aeronomy of Ice in the Mesosphere (AIM) satellite system beginning in 2007.

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ISS031-E-116058 (13 June 2012) --- Polar mesospheric clouds in the Northern Hemisphere are featured in this image photographed by an Expedition 31 crew member on the International Space Station. In both the Northern and Southern Hemisphere, during their respective late spring and early summer seasons, polar mesospheric clouds are at the peak of their visibility. Visible from the ground during twilight, aircraft in flight, and the International Space Station, they typically appear as delicate shining threads against the darkness of space?hence their other name of noctilucent or ?night-shining? clouds. On the same day this image was taken from the space station while it was passing over the night-darkened Tibetan Plateau, polar mesospheric clouds were also visible to aircraft flying above Canada. In addition to this still image, the space station crew took a time-lapse image sequence of polar mesospheric clouds several days earlier (June 5, 2012) while passing over western Asia; this is first such sequence of images of the phenomena taken from orbit. Polar mesospheric clouds form between 76-85 kilometers above the Earth?s surface, when there is sufficient water vapor at these high altitudes to freeze into ice crystals. The clouds are illuminated by the setting sun while the ground surface below is in darkness, lending them their night-shining properties. In addition to the illuminated tracery of polar mesospheric clouds trending across the center of the image, lower layers of the atmosphere are also illuminated; the lowest layer of the atmosphere, the stratosphere, is indicated by dim orange and red tones. While the exact cause of formation of polar mesospheric clouds is still debated?dust from meteors, global warming, and rocket exhaust have all been suggested as contributing factors?recent research suggests that changes in atmospheric gas composition or temperature has caused the clouds to become brighter over time.

Earth Observations

ISS024-E-006136 (16 June 2010) --- Polar mesospheric clouds, illuminated by an orbital sunrise, are featured in this image photographed by an Expedition 24 crew member on the International Space Station. Polar mesospheric, or noctilucent (?night shining?), clouds are observed from both Earth?s surface and in orbit by crew members aboard the space station. They are called night-shining clouds as they are usually seen at twilight. Following the setting of the sun below the horizon and darkening of Earth?s surface, these high clouds are still briefly illuminated by sunlight. Occasionally the ISS orbital track becomes nearly parallel to Earth?s day/night terminator for a time, allowing polar mesospheric clouds to be visible to the crew at times other than the usual twilight due to the space station altitude. This unusual photograph shows polar mesospheric clouds illuminated by the rising, rather than setting, sun at center right. Low clouds on the horizon appear yellow and orange, while higher clouds and aerosols are illuminated a brilliant white. Polar mesospheric clouds appear as light blue ribbons extending across the top of the image. These clouds typically occur at high latitudes of both the Northern and Southern Hemispheres, and at fairly high altitudes of 76?85 kilometers (near the boundary between the mesosphere and thermosphere atmospheric layers). The ISS was located over the Greek island of Kos in the Aegean Sea (near the southwestern coastline of Turkey) when the image was taken at approximately midnight local time. The orbital complex was tracking northeastward, nearly parallel to the terminator, making it possible to observe an apparent ?sunrise? located almost due north. A similar unusual alignment of the ISS orbit track, terminator position, and seasonal position of Earth?s orbit around the sun allowed for striking imagery of polar mesospheric clouds over the Southern Hemisphere earlier this year.

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ISS031-E-123071 (14 June 2012) --- The Great Lakes in sunglint are featured in this image photographed by an Expedition 31 crew member on the International Space Station. From the vantage point of the space station, crew members observe many spectacular phenomena including aurora, noctilucent clouds, airglow, and sunglint on Earth?s water bodies. Sunglint is light reflected off of a water surface towards the observer such that it creates the appearance of a mirror-like surface. If the viewing and lighting conditions are ideal, that mirror-like surface can extend over very large areas, such as the entire surface of Lake Ontario (approximately 18,960 square kilometers). This photograph was taken while the space station was located over a point to the southeast of Nova Scotia (approximately 1,200 kilometers ground distance from the center point of the image). Lake Ontario, Lake Huron, the Finger Lakes of upstate New York, and numerous other bodies of water appear brilliantly lit by sunglint. To the west, Lake Erie is also highlighted by sunglint, but less light is being reflected back towards the observer resulting in a duller appearance. Much of central Canada is obscured by extensive cloud cover in the image, whereas a smaller grouping of clouds obscures the Appalachian range and Pennsylvania (lower left). The blue envelope of Earth?s atmosphere is visible above the curved limb, or horizon line that extends across the upper third of the image. Such panoramic views of the planet are readily taken through space station viewing ports with handheld digital cameras which allow the crew to take advantage of the full range of viewing angles.

Earth Observations taken by the Expedition 22 Crew

ISS022-E-052281 (30 Jan. 2010) --- Polar mesospheric clouds over the Southern Hemisphere are featured in this image photographed by an Expedition 22 crew member on the International Space Station. This striking view shows polar mesospheric clouds (PMC) over the polar region of the Southern Hemisphere. These clouds occur over the high latitudes of both northern and southern hemispheres during their respective summer months at very high altitudes of approximately 76?85 kilometers. When present they are visible during twilight, when the clouds are illuminated by the sun while the ground surface below is in darkness. The International Space Station (ISS) orbit extends from latitude 52 North to latitude 52 South; combined with the highly oblique views through Earth?s atmosphere possible with hand-held imagery, the ISS is an ideal platform for documenting these transient, high altitude phenomena. Another NASA mission, the Aeronomy of Ice in the Mesosphere or AIM satellite, is dedicated to the study of PMC and is providing daily information about their formation, distribution, and variability. Polar mesospheric clouds are also known as noctilucent or night-shining clouds ? a property that is clearly visible in this photograph. The PMC exhibit thin, wispy light blue forms that contrast with the darkness of space above (upper right). Lower levels of cloud are strongly illuminated by the sun and appear light orange to white. Clouds closest to Earth?s surface are reddish-orange (center). The image was taken approximately 38 minutes after midnight Greenwich Mean Time (GMT) while the ISS was located over the southern Atlantic Ocean. At this time of year, the sun never sets over Antarctica but rather defines an arc across the local horizon, allowing PMC to be observed near local midnight.

Earth Observation taken by STS-117 crewmember on Space Shuttle Atlantis

S117-E-06998 (10 June 2007) --- Polar Mesospheric Clouds are featured in this image photographed by a STS-117 crewmember onboard Space Shuttle Atlantis. Sometimes in the summertime in the far northern (or southern) latitudes, high in the Earth's atmosphere at the edge of space, thin silvery clouds form and are observed just after sunset. These high clouds, occurring at altitudes of about 80 kilometers (50 miles), are called Polar Mesospheric Clouds (PMC) or noctilucent clouds, and are the subject of new studies to determine whether their occurrence is related to global climate change. Observations over the past few years suggest that PMC are now observed more frequently and at lower latitudes than historical observations. Several studies related to the International Polar Year (IPY), and the AIM (Aeronomy of Ice in the Mesosphere) spacecraft are underway to collect relevant data on the chemistry and physics of the mesosphere that might explain the occurrence of PMC. Astronauts in orbiting spacecraft frequently observe PMC over Canada, northern Europe and Asia during June, July and August. While PMC also occur over the high latitudes in the southern hemisphere in December, January and February, astronaut observations of southern PMC are less frequent. Earlier in June 2007, the shuttle crew visiting the International Space Station observed spectacular PMC over north-central Asia. This image was taken looking north while the shuttle and station were docking and flying over the border between western China, Mongolia and Kazakhstan. The red-to-dark region at the bottom of the image is the dense part of the Earth's atmosphere. Because this image was taken with a long lens (180mm), the entire profile of the Earth's limb is not captured. To support IPY research over the next 2 years, station crewmembers will be looking for and documenting PMC in both hemispheres.