Astronomy Picture of the Day

Explanation:

在火星的一座大峽谷裡，陡峭的斜坡從平滑的高原下沉，露出引人注目的岩石分層結構。 這個峽谷，是跨越火星赤道、長達4000公里的水手峽谷系統的一部分。 這幅影像則是由繞火星軌道上的火星全球探勘者號攝於1月1日，呈現了小部分的水手峽谷之極細微結構。 這幅影像的跨幅約為10公里，高分辨率版本顯示的特徵最小可小至6公尺。 是什麼過程造就了這些層狀結構呢？ 在地球上的大峽谷裡，沉積作用導致了壯觀的岩層。 但夏威夷群島峽谷裡的類似岩層，卻是由火山所形成的。 無論火星上的分層是由何種原因造成的，其伸展範圍顯示早期的火星地質上很活躍且複雜。

In a grand canyon on Mars, steep slopes fall away from a smooth plateau revealing striking layered rock formations. The canyon is part of the Valles Marineris, a 2,500 mile long system of canyons cutting across the Martian equator. This view, recorded on January 1 by the orbiting Mars Global Surveyor shows a small portion of Valles Marineris in amazing detail. The image is about 6 miles wide and high resolution versions show features as small as 20 feet across. What processes caused the layering? In the Grand Canyon on planet Earth, sedimentary processes have resulted in spectacular rock layers. But similar layers of rock in canyons of the Hawaiian Islands were created by volcanoes. Regardless of the origin of layering on Mars, its extent suggests that early Mars was geologically active and complex.