Star Light Star Bright : 無料・フリー素材/写真
Star Light Star Bright / NASA Goddard Photo and Video
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | In this view of the moon a sharp reflectance contrast is found in Humboldt crater (26.593°S; 83.764°E). Illumination is from the west, north is up, image is ~850m wide.Credit: NASA/GSFC/Arizona State UniversityWhy do we see such a sharp contrast in reflectance in the above Featured Image between the crater wall on the left and the crater floor on the right? This is the floor and wall of an ~8.5-km diameter, unnamed impact crater within the much larger Humboldt crater on the lunar farside. The reason for the striking dichotomy in terrain appearance is not a mystery -- it has to do with solar illumination angle. Our star, the sun is shining from the west at an elevation above the lunar horizon (~25°) that is close to the slope of the western crater wall. Thus much of the wall on this side is receiving low-angle sunlight and appears relatively dark compared to the crater floor surface, which is more directly illuminated. The floor makes a clean contact with the crater walls, and becomes a zone of deposition for boulders rolling down the slope, including one larger and prominent boulder at the southern end of the frame.For reasons like this, planetary scientists need to be careful when making interpretations of surface features, and must often use several images collected under a variety of lighting geometries to understand the geomorphology. NASA image use policy.NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.Follow us on TwitterLike us on FacebookFind us on Instagram |
| 撮影日 | 2013-05-30 11:07:27 |
| 撮影者 | NASA Goddard Photo and Video , Greenbelt, MD, USA |
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