The First Day of Southern Spring
The First Day of Southern Spring
ESP_028956_0930  Science Theme: Seasonal Processes
This image was taken on the first day of spring in the Southern hemisphere. Like the Earth, Mars is tilted on its axis, and the sun crosses the equator twice each year. On Earth we call this the equinox.

In the winter a seasonal polar cap composed of dry ice covers the polar regions. Although this is just the first day of spring and the sun is very low in the sky, activity associated with the sublimation (going directly from solid to gas) of the polar cap is already underway. A layer of ice coats this entire scene, and fans of dark material are deposited on top of the ice. This dark material is carried to the top of the ice by escaping gas flowing through the spidery channels carved in the surface.

In the summer, when the ice is gone, the fans are no longer visible.

Written by: Candy Hansen (audio by Tre Gibbs)  (7 November 2012)

This is a stereo pair with ESP_028957_0930.
Acquisition date
29 September 2012

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
248.3 km (154.3 miles)

Original image scale range
54.7 cm/pixel (with 2 x 2 binning) so objects ~164 cm across are resolved

Map projected scale
50 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
89°, with the Sun about 1° above the horizon

Solar longitude
180.0°, Northern Autumn

For non-map projected images
North azimuth:  104°
Sub-solar azimuth:  38.0°
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Black and white
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non-map           (157MB)

IRB color
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non-map           (154MB)

Merged IRB
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RGB color
non map           (141MB)
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

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Color label
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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/JPL/University of Arizona

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.