On April 30, 2013 the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature approved new names for five broad valleys on Mercury (see Angkor Vallis). These valleys have been interpreted by MESSENGER team scientists as having formed due to mechanical and thermal erosion of Mercury's surface by hot, low-viscosity, quickly-flowing lavas.

Each image this week will feature one of these five broad valleys, now termed "valles" (sing. "vallis") by the IAU. The valleys are named according to the theme of "abandoned cities (and towns and settlements) of antiquity" that was developed especially for these landforms.

The vallis shown in this figure is named for Angkor city in Cambodia, the largest pre-industrial city in the world, and once the seat of the Khmer Empire. At its peak, Angkor hosted over 1,000 temples, including the world's largest religious monument. With a suburban footprint of ca. 1,000 km², Angkor at one time may have had a population of over 1 million people. This image is a portion of the MDIS global mosaic basemap that was acquired during MESSENGER's first year in orbit.

Date Created: March 26, 2013
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Feature Latitude Range: 56.2° N to 58.4° N
Feature Longitude Range: 112.7° E to 115.6° E
Feature Diameter: 95 km
Resolution: 250 meters/pixel
Projection: Azimuthal equidistant

The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.

For information regarding the use of images, see the MESSENGER image use policy.