Astronomy Picture of the Day

Explanation:

這道位於火星表面的峽谷，看起來像是由流切割而成。 納內迪峽谷裡的台地和流道，強烈暗示曾經有水流動。 但是缺乏較小的表面流道和其他特徵，顯示這個山谷的成因也可能是表面坍塌。 未來針對火星峽谷系統所拍攝的影像，將有助於鑑別這些過程對火星表面的影響程度。 這幅影像是火星全球勘測者號的相機，於1月8日的繞火星第87個軌道上拍攝的。 這幅影像所呈現的區域寬約10公里，而在高解析版本的影像裡，可解析的最小結構體為16公尺。

This canyon on the surface of Mars appears to have been carved by flowing water. Known as Nanedi Vallis, the terraces and channels visible within the canyon strongly suggest that a river of water once ran here. But the lack of smaller surface channels and other features argue that the valley was formed by a surface collapse. Further images of Martian valley systems will help distinguish the degree to which these processes affected the Martian surface. This image was recorded on January 8th by the Mars Global Surveyor's camera during its 87th orbit of the red planet. The area pictured is about 6 miles wide. High resolution versions of the image show features that are as small as 40 feet across.