“金星伴月”即将浪漫上演，“星月”是如何“邂逅”的？

你听说过“金星伴月”吗？天文科普专家介绍，5月23日傍晚，月球和金星这两个夜空中最明亮的天体将会在西边天空“邂逅”，上演浪漫的“星月童话”。

月亮与金星、火星组成了一个漂亮的天体三角形，其中，月亮处于最高的位置上。这一“三角组合”的景象将会非常美妙，并且值得一拍。

The moon forms the apex of a beautiful celestial triangle involving the planets Venus and Mars. The trio should be a lovely sight as the sky darkens and will be a scene well worth trying to photograph.

那么这一浪漫的“星月童话”是如何形成的呢？

当月球位于地球和太阳的正中间时，就会出现新月。两个天体的天文经度（地球经线在天空中的投射）重合，这个位置也被称作合点。因为这一现象出现在白天，太阳十分明亮，所以除了日食的特殊情况，我们很难看到新月的诞生。

New moons occur when the moon is directly between Earth and the sun. The two bodies share their celestial longitude, a projection of Earth's longitude lines on the sky, a position also known as a conjunction. Since they are in the daytime, and the sun is so bright, it's not possible to see a new moon unless there is a solar eclipse.

5月23日，诞生4天的新月将会近距离掠过金星（称为逆冲）。二者将会在傍晚时分接近彼此，彼时的新月将位于金星和火星之间。

On May 23, the 4-day-old moon will make a close pass to Venus (called an appulse). The two will still appear close to each other at sunset; the crescent moon will be between Venus and Mars.

合相是两个天体在天空中共享相同的赤经或黄经时发生的天文现象。根据 starwalk.space的数据，每27.3天，月亮就会穿过天空中以黄道为中心的一部分狭窄区域，并与行星相遇。

A conjunction is an astronomical phenomenon occurring when two celestial objects share the same right ascension or ecliptic longitude in the sky. Once every 27.3 days, the moon passes through a narrow part of the sky centered on the ecliptic and encounters planets, according to starwalk.space.

行星之间的合相经常发生，这是因为天体之间在大致相同的平面上围绕太阳公转，在我们看到的天空中也沿着相似的轨迹运行。

Conjunctions between planets happen frequently because the celestial bodies orbit around the sun in approximately the same plane as one another and trace similar paths across our sky.

合相没有特别的天文学意义，但却是一个引人注目的奇观。

Conjunctions have no particular astronomical significance, but they are a striking spectacle to view.

NASA在3月24日发布的金星伴月推文

关于明亮的恒星与行星之间的各种合相每年都有发生。站在地球上的有利位置，在行星围绕太阳旋转的过程中，我们很容易肉眼观察到水星、金星、火星、木星和土星。这些行星都以自己的速度和轨道移动。也正因为它们持续以不同的速度运转，这五颗行星在任何时刻的位置都是独一无二的。

A wide variety of different conjunctions and configurations involving bright stars and planets typically occur during the course of any given year. From our Earthly vantage point, we can readily observe Mercury, Venus, Mars, Jupiter and Saturn with our unaided eyes as they revolve around the sun. Each of these planets appears to move against the starry background at their own speeds and along their own tracks. It is obvious that since they are constantly moving at different speeds, the positions of all five planets at any particular time are unique to that particular moment.

明天晚上，喊上你的好朋友一起去看“金星伴月”吧！

编辑：商桢

实习生：刘子涵

来源：新华社 CGTN Space.com Star-News