Astronomy Picture of the Day

Explanation: To learn about the history ofMars, just ask the rocks. Last year, that's exactly what the robot rover Sojourner did. Sojouner can be seen, above, analyzing a rock nicknamed Moe, trying to discern its past. One significant discovery of the Mars Pathfinder mission was that of conglomerate rocks, indicating the presence of running water in the past. Such water, in turn, indicates that Mars was much more like watery Earth in the distant past. Visible in the foreground of this color-enhanced mosaic is part of the Sagan Memorial Station, while a hill nicknamed one of the "Twin Peaks" is visible about a kilometer in the distance.

要了解火星的歷史，只需要去問它的岩石。 而這正是火星探測車寄居者號（Sojouner）在去年所做的事情。 在上圖可見到寄居者號正在分析一塊稱為Moe的岩石，以試圖解讀它的過去。 火星探路者號任務的重要成果之一是發現礫岩，而這顯示火星過去曾有水泛流。 水的存在可反過來暗示：遙遠過去的火星很像地球這種水世界。 在這幅彩色強化併接影像的前景，可以看到部分的薩根紀念站，而在1公里之外的遠處，則有一座暱稱為“雙峰之一”的火星山丘。