Long Shadows at Ariadnes Colles
Long Shadows at Ariadnes Colles
PSP_009161_1450  Science Theme: Glacial/Periglacial Processes
Ariadnes Colles is a labyrinth-like cluster of hills, mesas, and knobs located near Terra Cimmeria, in the Southern Highlands of Mars.

This image, which covers a portion of that labyrinth, was acquired only a few sols (Martian days) away from winter solstice. Winter solstice occurs in the shortest sol of the year, when the Sun travels the lowest in the Martian sky, making shadows appear very long. These conditions are ideal to analyze modest relief features, that would pass unnoticed when illuminated from above but are highlighted when illuminated from the side.

This subimage of the enhanced-color combination shows one of the hills in detail.

The hill appears criss-crossed by long fractures, most of them made apparent by the shadows they cast. The shadows indicate that the fractures "stick out" from their surroundings, and hence that they are more resistant to erosion. In terrestrial environments this occurs when fluids flow along the fractures, leaving behind cementing minerals or when fractures are filled by igneous materials.

Written by: Sara Martinez-Alonso  (27 August 2008)
Acquisition date
10 July 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
253.9 km (157.8 miles)

Original image scale range
50.8 cm/pixel (with 2 x 2 binning) so objects ~153 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
78°, with the Sun about 12° above the horizon

Solar longitude
96.7°, Northern Summer

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  48.5°
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

Black and white
map-projected   (522MB)

IRB color
map-projected   (242MB)

Black and white
map-projected  (253MB)
non-map           (246MB)

IRB color
map projected  (74MB)
non-map           (230MB)

Merged IRB
map projected  (455MB)

Merged RGB
map-projected  (441MB)

RGB color
non map           (227MB)
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:

NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.