Mars Pathfinder

Dr. Mark Lemmon, University of Arizona
Mars Pathfinder Imaging Team

On Sol 39 there were wispy blue clouds in the pre-dawn sky of Mars, as seen by the Imager for Mars Pathfinder. The color image was made by taking blue, green, and red images and then combining them into a single color image. The clouds appear to have a bluish side and a greenish side because they moved (in the wind from the northeast) between images. This picture was made an hour and twenty minutes before sunrise -- the sun is not shining directly on the water ice clouds, but they are illuminated by the dawn twilight.

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These clouds from Sol 15 have a new look. As water ice clouds cover the sky, the sky takes on a more bluish cast. This is because small particles (perhaps a tenth the size of the Martian dust, or one-thousandth the thickness of a human hair) are bright in blue light, but almost invisible in red light. Thus, scientists expect that the ice particles in the clouds are very small. The clouds were imaged by the Imager for Mars Pathfinder (IMP).

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These are more wispy blue clouds from Sol 39 as seen by the Imager for Mars Pathfinder. The bright clouds near the bottom are about 10 degrees above the horizon. The clouds are believed to be at an altitude of 10 to 15 km, and are thought to be made of small water ice particles. The picture was taken about 40 minutes before sunrise.

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These are more wispy blue clouds from Sol 39 as seen by the Imager for Mars Pathfinder. The bright clouds near the bottom are about 30 degrees above the horizon. The clouds are believed to be at an altitude of 10 to 15 km, and are thought to be made of small water ice particles. The picture was taken about 35 minutes before sunrise

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This is a close-up of the sunset on Sol 24. The red sky in the background and the blue around the Sun are approximately as they would appear to the human eye. The color of the Sun itself is not right -- the Sun was over exposed in each of the 3 color images that were used to make this picture.The true color of the Sun itself may be near white or slightly bluish

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This image of the Martian sunset from Sol 24 shows much more color variation than had previously been seen. The blue color near the Sun is not caused by clouds of water ice, but by the Martian dust itself. The dust in the atmosphere absorbs blue light, giving the sky its red color, but it also scatters some of the blue light into the area just around the Sun because of its size. The blue color only becomes apparent near sunrise and sunset, when the light has to pass through the largest amount of dust.

This true color image shows the eastern sky, 30 degrees above the horizon at 05:13 local solar time on Sol 39. The bright streaks are probably ice clouds which have formed during the night. In the true colour image, the clouds appear to be blue compared to the background. This is a real effect. Unlike the red dust, the clouds are almost invisible at infrared wavelengths.

The clouds are also moving. In order to create this image, the individual, single color, data frames have had to be shifted with respect to each other. The motion indicates that the clouds are moving from the north-east to the south-west.


This animation shows three images taken on the morning of Sol 16. Between frames, you can see the clouds moving across the screen from the northeast. The clouds are thought to be about 10 miles high and moving in 15 mile per hour winds.


On sol 25, as the Hubble Space Telescope was preparing to take images of mars including the Pathfinder landing site, IMP watched the sunrise. This sequence of images was taken through the blue filter, and shows the sky just before sunrise continuing until the Sun rises out of the field of view. These images were taken as part of an atmospheric imaging project that was coordinated with the Space Telescope observations. They are also useful for refining our knowledge of the orientation of the landing site -- the position and timing of the sunrise give us a very good direction reference.

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This image was taken by the Imager for Mars Pathfinder (IMP) about one minute after sunset on Mars on Sol 21. The prominent hills dubbed "Twin Peaks" form a dark silhouette at the horizon, while the setting sun casts a pink glow over the darkening sky. The image was taken as part of a twilight study which indicates how the brightness of the sky fades with time after sunset. Scientists found that the sky stays bright for up to two hours after sunset, indicating that Martian dust extends very high into the atmosphere.

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Sol 24 sunset showing the sun sinking into the horizon.	False color view of the sunset.
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A detail of the sunset showing a fan-shaped scattering of light.	Stills of the sunrise with false color.
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False color view of the sunset.

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Animation of the Martian sunset. This movie is made from nine images of the twilight following sunset over Ares Vallis. The images are enhanced in order to show the very subtle features in the haze, which are probably caused by layers that are slightly dustier than the surrounding air. The color is not the true color of the sunset -- that is shown in other images. At the beginning, the Sun is on the horizon just to the right of the frame, and it sinks during the next hour. At the time of the last image the sky is only 1% as bright as at the beginning, but the IMP can easily adapt to the darkness and return these pictures. Because there is so much dust extending high into the martian sky, the sky stays bright for more than an hour after sunset.

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Pink stratus clouds are coming from the northeast at about 15 miles per hour (6.7 meters/second) at an appoximate height of ten miles (16 kilometers) above the surface. The clouds consist of water ice condensed on reddish dust particles suspended in the atmosphere. Clouds on Mars are sometimes localized and can sometimes cover entire regions, but have not yet been observed to cover the entire planet. The image was taken by the Imager for Mars Pathfinder (IMP) on Sol 16 about forty minutes before sunrise showing areas of the eastern Martian horizon.
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This is the first color image ever taken from the surface of Mars of an overcast sky. Featured are pink stratus clouds coming from the northeast at about 15 miles per hour (6.7 meters/second) at an appoximate height of ten miles (16 kilometers) above the surface. The clouds consist of water ice condensed on reddish dust particles suspended in the atmosphere. Clouds on Mars are sometimes localized and can sometimes cover entire regions, but have not yet been observed to cover the entire planet. The image was taken about an hour and forty minutes before sunrise by the Imager for Mars Pathfinder (IMP) on Sol 16 at about ten degrees up from the eastern Martian horizon.	This is the first image ever taken from the surface of Mars of an overcast sky. Featured are stratus clouds coming from the northeast at about 15 miles per hour (6.7 meters/second) at an approximate height of ten miles (16 kilometers) above the surface. The "you are here" notation marks where Earth was situated in the sky at the time the image was taken. Scientists had hoped to see Earth in this image, but the cloudy conditions prevented a clear viewing. Similar images will be taken in the future with the hope of capturing a view of Earth. From Mars, Earth would appear as a tiny blue dot similar to how a star would appear to an earthbound observer. Pathfinders' imaging system will not be able to resolve Earths' moon. The clouds consist of water ice condensed on reddish dust particles suspended in the atmosphere. Clouds on Mars are sometimes localized and can sometimes cover entire regions, but have not yet been observed to cover the entire planet. The image was taken about an hour and forty minutes before sunrise by the Imager for Mars Pathfinder (IMP) on Sol 16 at about ten degrees up from the eastern Martian horizon.

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