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Have you heard that an asteroid might—just maybe—smack into Earth sometime in the next few years? The rumors are true, though perhaps not as frightening as you might think.[qh]
您是否听说过，在未来几年内，一颗小行星可能会（只是有可能）撞击地球？这些传言是真的，但可能没有您想象的那么可怕。[qh]
The fact is that this asteroid, called 2024 YR4, is both literally and figuratively a moving target.[qh]
事实上，这颗名为2024 YR4的小行星，无论是从字面意义上还是从象征意义上来说，都是一个移动目标。[qh]
As of February 11, the European Space Agency estimated that the space rock has a 2 percent chance of colliding with Earth on December 22, 2032.[qh]
截至2月11日，欧洲航天局估计，这颗太空岩石在2032年12月22日与地球相撞的概率为2%。[qh]
That's slightly higher than the risk you'll hear quoted in the episode that follows because we recorded it last week.[qh]
这比您在下期节目中听到的风险略高，因为我们上周录制了它。[qh]
Why are those numbers changing so quickly? We promise this isn't a matter of the risk going higher and higher as time goes on. It's a lot more complicated than that.[qh]
为什么这些数字变化如此之快？我们保证，这不是风险随着时间的推移越来越高的问题。它比这复杂得多。[qh]
Here to explain what's going on with this potentially hazardous asteroid is Lee Billings, a senior editor covering space and physics for Scientific American.[qh]
《科学美国人》太空和物理高级编辑Lee Billings将在这里解释这颗潜在危险小行星的情况。[qh]
Lee, thanks so much for coming on to chat. It's my pleasure, as always, Rachel.[qh]
Lee，非常感谢您来聊天。和往常一样，这是我的荣幸，Rachel。[qh]
So there's an asteroid with a very low chance of hitting us. Why did this make such a big splash in the news?[qh]
有一颗小行星撞击我们的可能性非常低。为什么这在新闻中引起了如此大的轰动？[qh]
So it made such a big splash in the news because, apparently, a 1 percent or greater chance of being struck by an asteroid is actually a big deal.[qh]
它之所以在新闻中引起如此大的轰动，是因为显然，被小行星撞击的概率为1%或更高实际上是一件大事。[qh]
And that's what this thing is. It's, it's called 2024 YR4—really rolls off the tongue.[qh]
就是这样。它被称为2024 YR4——真的很顺口。[qh]
It was discovered on December 27 by astronomers using the Asteroid Terrestrial-Impact Last Alert System, or ATLAS, which is a telescope in Chile.[qh]
天文学家于12月27日使用小行星陆地撞击最后警报系统（ATLAS）发现了它，这是智利的一架望远镜。[qh]
When it was roughly about two times farther out than our moon, it was zooming right by our planet, and folks were able to look at its orbit,[qh]
当它距离地球大约比我们的月球远两倍时，它就飞快地掠过我们的星球，人们能够看到它的轨道，[qh]
which they're still piecing together, and determined that it was gonna make another especially close pass on December 22, 2032.[qh]
他们仍在拼凑它的轨道，并确定它将在2032年12月22日再次近距离飞过地球。[qh]
And at that time it had about a 1.3 percent chance of striking our planet.[qh]
当时它撞击地球的概率约为1.3%。[qh]
Got it. So how did we detect this? You mentioned ATLAS, but tell me more about what that telescope does and whose job it is to keep an eye out for these asteroids.[qh]
明白了。那么我们是如何探测到它的？你提到了ATLAS，但请告诉我更多关于该望远镜的功能以及谁负责监视这些小行星的信息。[qh]
Last I counted there's somewhere between a half dozen and a dozen wide-field survey telescopes that look at the sky every night, and what they're looking for is moving objects. What do we mean by moving? Everything's moving.[qh]
我最后统计了一下，大约有六到十二台广角巡天望远镜每天晚上都会观测天空，它们正在寻找移动的物体。我们所说的移动是什么意思？一切都在移动。[qh]
We're looking for objects that seem to move against the background of the more distant stars, which don't seem to move 'cause they're so far away.[qh]
我们正在寻找似乎在更远的恒星背景下移动的物体，这些物体似乎没有移动，因为它们距离太远了。[qh]
You can do that by comparing images to each other over time—image A, image B; image A, image B—and you can see a difference, an offset in, in some little point of light. And that'll tell you: that thing's moving.[qh]
你可以通过比较不同时间的图像来做到这一点——图像A、图像B——你可以看到差异，在某个小光点中有一个偏移。这会告诉你：那个东西在移动。[qh]
Most of the time, when they see these things, they know what they are; they're already cataloged. They can quickly refine their orbit, figure out what it is—"Oh, it's this thing in the catalog, sure."[qh]
大多数情况下，当它们看到这些东西时，它们知道它们是什么；它们已经被编入目录。它们可以快速优化它们的轨道，找出它是什么——“哦，这是目录中的东西，当然。”[qh]
But they discover new objects all the time, and most of them prove to be totally harmless, just whizzing by through the solar system. Every now and then, however, one looks a little worrisome.[qh]
但它们一直在发现新物体，其中大多数被证明是完全无害的，只是在太阳系中呼啸而过。然而，偶尔，有一个看起来有点令人担忧。[qh]
The official threshold for being worrisome is if it's somewhere between 50 meters [about 164 feet] or greater in size,[qh]
令人担忧的官方门槛是如果它的尺寸在50米[约164英尺]或更大，[qh]
'cause then it could cause significant damage to Earth if it struck us, and if it's greater than about a 1 percent chance.[qh]
因为如果它撞击我们，可能会对地球造成重大破坏，并且如果它的概率大于1%。[qh]
And I keep using some caveats here about how certain we are about this thing striking us because this is not a settled story.[qh]
我在这里不断使用一些警告，说明我们对这个物体撞击地球的确定程度，因为这不是定论。[qh]
This is still so fresh that we don't actually have this object's orbit totally refined. We're still getting more information about it.[qh]
这件事仍然很新鲜，我们实际上还没有完全确定这个物体的轨道。我们仍在获取有关它的更多信息。[qh]
We're still observing this thing and trying to figure out what exactly it's going to be doing, where exactly it's going in space.[qh]
我们仍在观察这个物体，试图弄清楚它到底会做什么，它到底会去太空的哪个地方。[qh]
Late last month, when our story about this published, the odds of it striking were about 1.6 percent. And then, in the following couple of days, they rose to 1.7 percent.[qh]
上个月底，当我们关于这件事的报道发表时，它撞击地球的几率约为1.6%。然后，在接下来的几天里，这个几率上升到了1.7%。[qh]
About three or four days after the story dropped the odds have gone back down to 1.4 percent.[qh]
在报道发表三四天后，几率又降到了1.4%。[qh]
So, you can see, it's very active and fluid, but the upshot essentially is that if it stays above 1 percent, then folks should be worried about it.[qh]
它非常活跃和不稳定，但本质上的结果是，如果它保持在1%以上，那么人们就应该担心它了。[qh]
As you said, we see lots of objects that we never end up having to worry about. How unusual is it to get something above that 1 percent threshold?[qh]
正如你所说，我们看到了很多我们永远不必担心的物体。超过1%的门槛有多不寻常？[qh]
The last time this happened was about 20 years ago. Okay! With an asteroid that you might have heard about called Apophis, right?[qh]
上一次发生这种情况是在大约20年前。好吧！你可能听说过一颗小行星，叫做阿波菲斯，对吧？[qh]
And Apophis, for a while, also had a greater than 1 percent chance of striking Earth, and it made big headlines, and people got really worried about it—I think it helped spark Hollywood movies and various space missions.[qh]
有一段时间，阿波菲斯撞击地球的几率也超过1%，这引起了广泛关注，人们对此非常担心——我认为这有助于启发好莱坞电影和各种太空任务。[qh]
To try to deflect asteroids—so it doesn't happen that often; that's one reason why it's newsworthy.[qh]
试图转移小行星——所以这种情况并不经常发生；这就是它值得报道的原因之一。[qh]
But I just wanna emphasize, of course, that typically what does happen with these things is: you'll see this initial oscillation in the chances of it striking Earth,[qh]
但我只想强调，当然，通常情况下，这些事情确实会发生：你会看到它撞击地球的几率最初出现波动，[qh]
and then they just fall off a cliff because we refine the orbit, we realize that we're safe, and that's that.[qh]
然后它们就掉下悬崖，因为我们优化了轨道，我们意识到我们是安全的，就是这样。[qh]
Sure. This one's a little special, though. T he reason why it's special has to do with what we already know about its orbit and how long it takes to prepare any adequate response to try to prevent disaster.[qh]
当然。不过，这个小行星有点特别。它之所以特别，是因为我们已了解它的轨道，以及需要多长时间才能准备好应灾措施。[qh]
Essentially, this thing is going to come back to Earth in 2028. We know we're safe from it then. It's already headed away from Earth.[qh]
从本质上讲，这个小行星将于2028年返回地球。我们知道那时我们不会受到它的威胁。它已经远离地球了。[qh]
It's whizzing away from us in the solar system. It's going to be too faint to see with telescopes by late April or early May.[qh]
它正在太阳系中飞驰而去。到4月底或5月初，它就会变得太暗，无法用望远镜看到。[qh]
