火卫一凌日
影像来源与版权:NASA, JPL-Caltech, MSSS, Curiosity Rover

说明:那个掠过太阳前方的天体是什么?它看起来像一颗卫星,但不可能是月球,因为它不是圆的。它是火星的卫星-火卫一。这段精彩的视频是好奇号火星车在上个月末从火星表面拍摄的。火卫一的直径为11.5公里,比月球的直径小150倍,但与其母星的距离也近了50倍。实际上,火卫一离火星如此接近,人们预计它将在未来5千万年内解体并撞向火星。在短期内,火卫一的低轨道运行所形成的日食比从地球上看到的更快。这段精彩的视频已经加速,实际掠过太阳的时间大约需要35秒钟。一段类似的视频拍摄到了火星更小、最远的卫星火卫二凌日的过程。这位摄像师好奇号火星车将继续探索盖尔环形山,最近这片区域有着极致的美景和被称为格伦.托里登的奇特岩石。
翻译:北京天文馆

Martian Moon Phobos Crosses the Sun
Image Credit & Copyright: NASA, JPL-Caltech, MSSS, Curiosity Rover

Explanation: What’s that passing in front of the Sun? It looks like a moon, but it can’t be Earth’s Moon, because it isn’t round. It’s the Martian moon Phobos. The featured video was taken from the surface of Mars late last month by the Curiosity rover. Phobos, at 11.5 kilometers across, is 150 times smaller than Luna (our moon) in diameter, but also 50 times closer to its parent planet. In fact, Phobos is so close to Mars that it is expected to break up and crash into Mars within the next 50 million years. In the near term, the low orbit of Phobos results in more rapid solar eclipses than seen from Earth. The featured video has been sped up — the actual transit took about 35 seconds. A similar video was taken of Mars’ smaller and most distant moon Diemos transiting the Sun. The videographer — the robotic rover Curiosity — continues to explore Gale crater, most recently an area with stunning vistas and unusual rocks dubbed Glen Torridon.
Astronomy Picture of the Day 04/10/2019