一颗小行星刚刚近距离划过地球，比月亮还近

With all the large asteroids hitting the news lately, it would have been easy for a small one to sneak under the radar. In fact, one very nearly did. On April 27, astronomers discovered a new asteroid, a little pixie of a space rock between 4 and 8 metres (13 to 26 feet) across.

最近很多大型小行星登上资讯，小号的小行星就很容易从雷达下溜走。有一颗小行星就差点溜掉了。4月27日，天文学家发现了一颗新的小行星，是一小块太空岩石，直径在4到8米（13到26英尺）之间。

It was already close to Earth at this point, and the probability of a collision was calculated at around 10 percent. At its size, it would have burnt up on atmospheric entry, so it posed no threat to humans anyway.

此时已经距离地球很近了，撞击概率是10%左右。这个尺寸的小行星进入大气层就会烧毁，所以对人类没有威胁。

But the asteroid's trajectory would bring it very close to the geostationary ring, the volume of space around Earth in which bodies can maintain geostationary orbit. That space is packed with satellites.

但这颗小行星的轨道使它非常靠近地球静止环，这是地球周围的一部分空间，其中的物体可以在地球静止轨道内运行。这一空间里到处都是卫星。

On April 28, this asteroid - later named 2020 HS7 - skimmed past Earth at a distance around nine times closer than the average distance of the Moon.

4月28日，这颗后来被命名为2020 HS7的小行星掠过地球，最近距离比地月平均距离近9倍。

At a distance of 42,735 kilometres (26,554 miles) from the centre of Earth - the Earth-Moon distance is 384,400 kilometres (238,855 miles) from centre to centre on average - 2020 HS7 pulled off one of the closest asteroid flybys we've ever seen.

地心到月球中心的地月平均距离是384,400千米（238,855英里），2020 HS7距地心最近距离是42,735千米（26,554英里），是我们所见过的掠过地球时距离最近的小行星。

And it skimmed the nearest satellite by just 1,200 kilometres (746 miles). That may sound a bit scary, but neither we nor our satellites were in any particular danger.

它与离它最近的卫星之间的距离仅为1,200千米（746英里）。这可能听起来有点吓人，但我们和卫星都没有太大的危险。

"Small asteroids like 2020 HS7 safely pass by Earth a few times per month," said astronomer Lindley Johnson of NASA's Planetary Defense Coordination Office just prior to the flyby. "It poses no threat to our planet."

美国国家航空航天局行星防御协调办公室的天文学家Lindley Johnson在小行星掠过之前说：“像2020 HS7这样小型的小行星每个月都会安全掠过地球几次，对地球并无威胁。”

In fact, 2020 HS7 was a good thing. It allowed scientists to test their detection, observation, follow-up and prediction capabilities on a small near-Earth asteroid. And they showed they were able to predict and track the path of 2020 HS7 with incredible accuracy, even with just a day's notice.

其实2020 HS7掠过是好事，让科学家能测试一下他们对小型近地小行星的探测、观测、跟踪和预测能力。而现在的结果是，即使只是提前一天得知，他们也能以惊人的精度预测并追踪2020 HS7的路径。