Ice Clouds - False Color (THEMIS_IOTD_20230911a)

The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows high altitude ice clouds. The blue and yellow bands in this image are not image artifacts, but are the traces of ice rich clouds. Each framelet of the image is collected at slightly different times. For the unchanging surface, this works fine. Optically thick dust clouds are usually close to the surface so any motion of the clouds is not dramatic as seen from the altitude of the Odyssey spacecraft. Transparent, and high altitude clouds are harder to discern in single band images - but are easy to discern in false color images - the clouds are in slightly different positions as each filter is collected. The clouds in this image are in the Tharsis region. Clouds are common there in the northern spring season. As clouds are a transient process, they can not be targeted, but are a 'surprise' when they are captured in an image.

The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

This martian scene spans 18 x 276 kilometers (11 x 171 miles). To see where on Mars this area lies, and to download high-resolution versions of the image go to themis.asu.edu/zoom-20230911a

See the Red Planet Report at redplanet.asu.edu for updates on Mars research and exploration. For more about Mars geology, check out the Mars-ePedia: marsed.asu.edu/marsepedia

For the latest THEMIS Mars images as received by mission scientists, see themis.asu.edu/livefrommars. To learn more about the THEMIS camera and its Mars images, see themis.asu.edu

This image is in the public domain and may be republished free of charge. If used, please credit it as NASA/JPL-Caltech/Arizona State University.

Taken on: September 11, 2023

Tags:

THEMIS

Thermal Emission Imaging System

ASU

School of Earth and Space Exploration

SESE

odyssey

marswatch

MSFF

Mars

Mars Space Flight Facility

Ice clouds

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Sets appears in: • Mars Images of the Day

Groups appears in: • Space Exploration • Mars Watch more » • Astronomy, Stars, Planets and Space • Sol System • Solar system and planets « less

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