A Flower-Shaped Rock on Mars
Image Credit: NASA, JPL-Caltech, MSSS
Explanation: It is one of the more unusual rocks yet found on Mars. Smaller than a penny, the rock has several appendages that make it look, to some, like a flower. Although it would be a major discovery if the rock was truly a fossilized ancient Martian flower, there are less spectacular — and currently preferred — explanations for its unusual structure. One theory that has emerged is that the rock is a type of concretion created by minerals deposited by water in cracks or divisions in existing rock. These concretions can be compacted together, can be harder and denser than surrounding rock, and can remain even after the surrounding rock erodes away. The flower structure may also be caused by crystal clusters. The small rock, named Blackthorn Salt, has similarities to previously imaged Martian pebbles. The featured image was taken by the Curiosity rover on Mars in late February. Scientists will continue to study data and images taken of this — and similar — surprising Martian rocks.
Review: Last Year in Space Pictures
Tomorrow’s picture: the toucan’s star cluster
影像提供: NASA, JPL-Caltech, MSSS
说明: 它是在火星上找到的较特殊石头之一。这块比铜板小带着数个分叉的石头，有人认为它形似花朵。如果它真的是火星花朵的化石，那这绝对是重大发现，只不过，目前诠释其特殊结构的较可能说法并没这么神奇。目前较受青睐的理论认为，这块石头可能是矿物质被水带入原先就存在的岩石之裂缝或分块缝隙后，凝结而成的。这些受压凝结的石块，可以比周围的石头更硬更致密，因此在周围的岩石受浸蚀消失后仍留存下来。另一种可能是，这个花形的石头是簇晶。这块名为黑刺盐（Blackthorn Salt）的小石头，其组成和先前拍摄过的火星鹅卵石相似。这幅主题影像是由好奇号火星车摄于今年1月底。科学家会持续研究和拍摄这颗及其他令人惊奇的火星岩石。
明日的图片: the toucan’s star cluster