Evening Shadows

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Caption:

The above MESSENGER images were taken on approach to Mercury during the spacecraft's second (left) and third (right) flybys. The image from the second flyby was featured in an earlier release. The image on the right was taken about 75 minutes before MESSENGER's closest approach. The two images cover very nearly the same terrain, but for the right image the Sun's illumination is more nearly grazing (local time is almost sunset) and the viewing perspective of the spacecraft is more nearly vertical. The large impact crater bisected with a prominent scarp or cliff is the same feature in both images. Because of Mercury's rotation between the two encounters, the position of the crater in the right image is nearly at the terminator (the division between the dayside and night side of the planet), and thus the shadows are longer. The near-grazing illumination emphasizes the topography of the crater floor, including the relief of the wrinkle ridges on either side of the large scarp. To the west of the crater, the shadows and viewing angle show that the terrain is far more rugged than it appeared from the second flyby.

Date Acquired: September 29, 2009
Image Mission Elapsed Time (MET): 16244187
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 400 meters/pixel (0.25 miles/pixel)
Scale: The large crater is 190 kilometers (120 miles) across; the scarp bisecting the crater is over a kilometer (almost a mile) high
Spacecraft Altitude: 15,500 kilometers (9,600 miles)

Background Info:

These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet, Mercury. For information regarding the use of images, see the MESSENGER image use policy .

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