NASA·APOD每日天文一图2022.6.28 [超高清]

月球？水星！“贝比科隆博号”探测器掠过水星拍下震撼照片！

Which part of the Moon is this? No part -- because this is the planet Mercury. Mercury's old surface is heavily cratered like that of Earth's Moon. Mercury, while only slightly larger than Luna, is much denser and more massive than any Solar System moon because it is made mostly of iron. In fact, our Earth is the only planet more dense. Because Mercury rotates exactly three times for every two orbits around the Sun, and because Mercury's orbit is so elliptical, visitors on Mercury could see the Sun rise, stop in the sky, go back toward the rising horizon, stop again, and then set quickly over the other horizon. From Earth, Mercury's proximity to the Sun causes it to be visible only for a short time just after sunset or just before sunrise. The featured image was captured last week by ESA and JAXA's passing BepiColombo spacecraft as it sheds energy and prepares to orbit the innermost planet starting in 2025. 

这是月球的哪一部分？哪都不是，因为这是水星。水星古老的表面像月球一样布满了撞击坑。水星虽然只比月亮略大，但它比太阳系任何一颗卫星的密度都要高得多，质量也更大，因为它主要是由铁构成的。事实上，在行星里，也只有我们的地球比它密度更高。水星很精确的每绕太阳公转两圈就自转三圈，而且水星的轨道非常椭圆，所以水星上的游客可以看到太阳升起，在天空中停留，然后竟然向升起处的地平线返回，并再次停留，最后向另一侧的地平线快速落下。从地球上看，水星与太阳在天空中总是离得很近，所以只能在日落后或日出前很短时间内才能看到。上周，欧洲空间局（ESA）和日本航天局（JAXA）的“贝比科隆博号”探测器掠过了这颗最内侧行星，拍摄了这张特色照片。该探测器计划从2025年开始环绕水星运行。