How to See the Giant Asteroid That Will Pass by Earth This Weekend

如何观测本周末掠过地球的巨型小行星

The European Space Agency (ESA) confirmed that this weekend, asteroid (152637) 1997 NC1 will make its closest approach to Earth in 400 years. There’s no risk it will hit Earth, but it will be visible through commercial telescopes and astronomical binoculars from various parts of the world. 欧洲航天局（ESA）确认，本周末，小行星 (152637) 1997 NC1 将迎来 400 年来距离地球最近的一次掠过。虽然它不会对地球构成撞击风险，但世界各地的天文爱好者可以通过商用望远镜和天文双筒望远镜观测到它。

The closest approach will occur on Saturday, June 27, when the asteroid will pass 2.56 million kilometers (1.59 million miles) from Earth—a distance equivalent to 6.6 times the distance between Earth and the moon. The object—with a diameter estimated to be between 700 meters and 1.6 kilometers—will not come this close again until 2133, according to the ESA. 最接近地球的时刻将发生在 6 月 27 日星期六，届时该小行星将从距离地球 256 万公里（约 159 万英里）处掠过——这一距离相当于地月距离的 6.6 倍。据欧航局估计，该天体直径在 700 米至 1.6 公里之间，下一次如此近距离地接近地球要等到 2133 年。

When Will the Asteroid Be Visible?

小行星何时可见？

The asteroid will be closest to the Earth on Saturday, June 27 at 11:14 UTC. The best time to view it will depend on your location, though. Here’s a rough breakdown for various regions: 该小行星将于协调世界时（UTC）6 月 27 日星期六 11:14 最接近地球。不过，最佳观测时间取决于你所在的地理位置。以下是各地区的观测时间概览：

• Europe: the night of June 26 to 27, especially in the early morning
• 欧洲： 6 月 26 日至 27 日夜间，尤其是清晨时段
• Mexico: the night of June 26 to 27
• 墨西哥： 6 月 26 日至 27 日夜间
• The US: the night of June 26 to 27, with the best viewing conditions before sunrise
• 美国： 6 月 26 日至 27 日夜间，日出前观测条件最佳
• Argentina and the Southern Cone: the night of June 27 to 28, once the asteroid has moved toward the southern sky
• 阿根廷及南锥体地区： 6 月 27 日至 28 日夜间，待小行星移向南半球天空后

The asteroid will not disappear immediately after its closest approach. It will remain visible for several days, although its brightness will gradually decrease and its position in the sky will shift. If you’re unable to observe it on the first night, you’ll still have opportunities in the following days, although conditions will be less favorable for those in the northern hemisphere. 小行星在最接近地球后并不会立即消失。它仍将在未来几天内保持可见，尽管其亮度会逐渐减弱，在天空中的位置也会发生偏移。如果你错过了第一晚的观测，后续几天仍有机会，不过对于北半球的观测者来说，条件会稍差一些。

What Will the Asteroid Look Like?

小行星看起来是什么样？

Despite being bigger than a skyscraper, the asteroid will be impossible to see with the naked eye. The ESA estimates that it will reach a brightness close to magnitude 10, similar to that of Neptune. 尽管这颗小行星比摩天大楼还要大，但肉眼是无法看到它的。欧航局估计其亮度将接近 10 等星，与海王星的亮度相当。

Through a telescope or astronomical binoculars, the asteroid will appear as a small point of light moving slowly among the stars. Its movement will be approximately 40 arc seconds per minute. It’s a somewhat obscure astronomical measure of movement, but suffice to say that it will be enough to notice the object moving if you watch it for a few minutes. 通过望远镜或天文双筒望远镜观察，小行星看起来就像一个在群星间缓慢移动的小光点。它的移动速度约为每分钟 40 角秒。这是一个相对专业的天文测量单位，但简单来说，只要你观察几分钟，就足以察觉到它在移动。

What Equipment Do You Need?

你需要什么设备？

You’re going to need more than your eyes. Even under the clearest night sky, the asteroid is 40 times fainter than the faintest stars the human eye can distinguish. The moon is also near full, which will reduce the contrast in the sky and make it harder to observe other objects in the night sky. 你不能仅靠肉眼观测。即使在最晴朗的夜空下，这颗小行星的亮度也比人眼能分辨的最暗恒星还要暗 40 倍。此外，由于正值满月前后，月光会降低天空对比度，使得观测其他天体变得更加困难。

At the moment of closest approach, it will be near the constellations Ophiuchus and Serpens Cauda, south of the bright star Vega. Astronomy apps such as Stellarium, Sky Tonight, or SkySafari, can help you locate where it is in the heavens at any given time by searching for “1997 NC1.” 在最接近地球的时刻，它将位于蛇夫座和巨蛇座尾部附近，织女星的南侧。你可以使用 Stellarium、Sky Tonight 或 SkySafari 等天文应用程序，搜索“1997 NC1”来定位它在天空中的位置。

For more than an apps-eye view, astronomers recommend using a commercial telescope with an aperture of at least 100 millimeters (4 inches), although models ranging from 150 to 200 millimeters will provide a much more comfortable viewing experience. It will also be possible to spot it with 15 x 70 or 20 x 80 astronomical binoculars, preferably mounted on a tripod and from a location away from light pollution. 如果想获得比手机应用更好的观测效果，天文学家建议使用口径至少为 100 毫米（4 英寸）的商用望远镜，而 150 至 200 毫米口径的型号将提供更舒适的观测体验。使用 15x70 或 20x80 的天文双筒望远镜也能观测到它，最好将其安装在三脚架上，并选择远离光污染的地点。

If it’s cloudy or you don’t have a telescope handy (or you just prefer watching celestial events from your couch), the Virtual Telescope Project is hosting livestreams on June 26 and June 27 that will track the asteroid. 如果遇到多云天气，或者你手头没有望远镜（或者你只是更喜欢坐在沙发上观看天象），“虚拟望远镜项目”（Virtual Telescope Project）将于 6 月 26 日和 27 日进行直播，实时追踪这颗小行星。