NASA's always on the lookout for possible asteroid collision hazards, so the Pan-STARRS telescope is scanning the sky every night. Each morning, candidate objects are examined by Pan-STARRS staff and usually discovered to be no big deal. But on October 19, 2017, Pan-STARRS spotted an object moving rapidly between the stars, and this time the usual follow-up measurements of position and speed showed something completely different. By October 22nd, we had enough data to realize that this object wasn't from our solar system.美国航空航天局（NASA）一直在进行 天文观测，以避免小行星碰撞的危险， 因此泛星计划的望远镜 每晚都在扫描天空。每天早上，泛星计划的工作人员 都会检查那些候选星体， 通常的结果都是：没有问题。但是2017年的10月19日， 泛星计划发现了一个 在星系间快速移动的物体， 这一次，例行的 位置和速度测量结果 显示了完全不一样的结果。到10月22日，我们有了足够的数据 证明这个物体不是来自太阳系。
Holy cow. That's when I got the phone call, the phone call that all solar system astronomers are waiting for. Let me tell you how exciting this was.我的天。我就是在那天接到的电话， 所有研究太阳系的天文学家 都在等这个电话。我来告诉你们这件事有多让人激动。
(Laughter)（笑声）
NASA's been expecting to see an interstellar comet pass through the solar system since the 1970s, but until now, we'd never seen anything. Our own solar system is huge, so even getting a package from the nearest star system 4.4 light years away would take over 50,000 years. So this is a really big deal. The interstellar visitor entered our solar system from above the plane of the planets, coming from the direction of the constellation Lyra, and it passed closest to the Sun on September 9th, passing inside the orbit of Mercury. Now this isn't a particularly close approach or unusual distance. It's just much easier to see objects close by. On October 14th, before we discovered it, it made its closest approach to the Earth, within about 15 million miles. This is really close by astronomical standards.从20世纪70年代开始， NASA就想找到一颗 跨星际飞行的彗星，能横穿太阳系， 但直到现在都没有任何发现。我们的太阳系很大， 即使从最近的、 离我们4.4光年的恒星系统 发点东西过来， 也需要5万年那么久。因此这件事真的非常重要。这位星际访客是从行星平面上方， 从天琴座的方向 进入我们的太阳系的， 它在9月9日经过了近日点， 从水星轨道内穿过。这个距离其实不算近， 属于正常范围。但是已经让我们的观测 变得容易多了。在10月14日， 在我们发现它之前， 它已经掠过了近地点， 差不多在1500万英里之内。就天文学的标准来说， 这已经相当近了。
Now rather than call this by its unwieldy catalog name, we briefly called it "Rama," after the cylindrical spacecraft that passed through the solar system in Arthur C. Clarke's classic science fiction story in 1973. But this wasn't quite right either, so in honor of it being discovered by a telescope in Hawaii, we consulted two experts on Hawaiian culture -- a Hawaiian navigator and a linguist -- to propose a name. And they suggested "'Oumuamua," which means scout or messenger from the distant past reaching out to us.我们没有按照枯燥的 目录命名来称呼它， 我们叫它“拉玛”， 名字来自于阿瑟 · C · 克拉克 1973年的经典科幻小说 里面那艘穿过太阳系的 圆柱形宇宙飞船。但其实这个名字也不太合适， 因为发现它的望远镜是在夏威夷， 于是我们找了两位夏威夷文化的专家， 一位夏威夷向导和一位语言学家， 来想一个名字。他们提议叫“奥陌陌”， 意思是经过长途跋涉 找到我们的侦察兵或者信使。
Now this discovery was important for many reasons, but to me the most significant is for what 'Oumuamua can tell us about the past of our solar system. The process of the birth of a new solar system and the growth of planets can be a violent and messy business. Leftover icy and rocky debris gets ejected from the new solar system as the giant planets migrate through the dusty disk out of which they're formed.这个发现之所以重要，有很多原因， 但我认为最有意义的是， 奥陌陌能告诉我们 我们太阳系的过去。一个新的恒星系统的诞生 和行星的成长 是一个剧烈而混乱的过程。多余的冰和岩石碎屑 被甩出这个新生的恒星系统。巨大的行星从它们诞生的尘埃中 穿越而过。
Now have you ever felt an emotional chill, something that's so exciting that a shiver runs up and down your spine? Or something that's very emotionally moving? Well this was it for me. This was my wow moment. We actually had a piece of material from another solar system coming close enough for us to observe.你们有没有感受过情绪的震颤， 就是有件事让你很激动， 一阵颤抖的感觉沿着你的脊柱上下？或者让你觉得非常受感动？我当时就是这种感觉。这是我的惊喜时刻。有一块从其他星系过来的物质 离得够近，可以让我们观察。
So what would you like to know about 'Oumuamua, the very first visitor from another star system? Well, I could think of a million things, but there's what you want and what you can have, and 'Oumuamua was moving away and fading very rapidly. In the span of about a week, it had dropped in brightness by a factor of [10]. So this is about all the time we were going to have to study it easily. So we had to distill the process of getting telescope time -- normally a very competitive, peer-reviewed proposal process that can take up to months -- down to less than a few days. So began a "polite" competition for resources. OK, let me not mince words. It was a fierce battle. We dropped everything, working around the clock, trying to craft perfectly crafted proposal words to send to the observatory directors. Well, good news. We got the time.关于奥陌陌，你们想知道些什么呢， 它是第一位来自另一个星系的访客。我可以想到一百万件事， 但是现实和理想总是有差距的， 奥陌陌当时正在离我们而去， 消失得非常快。在差不多一周的时间里， 它的亮度就下降了百分之一。因此我们能用来方便地研究它的时间 非常有限。因此我们要加快申请使用望远镜， 申请过程充满竞争、手续繁杂， 通常要花几个月的时间， 而我们只有几天的时间。于是开始了一场 “礼貌地”争夺资源的竞争。好吧，还是不要说反话了。那是一场激烈的战斗。我们放下了所有的事情， 跟时间赛跑， 试图写出一篇完美的申请报告 发给天文台台长。好在事遂人愿， 我们申请到了使用时间。
Now, from a perfectly selfish point of view, the first thing we might like to know is how massive 'Oumuamua is. Because after all, it passed very close to the Earth, and we didn't know about it until afterwards. How bad would this have been had it not missed the Earth? Well, the impact energy depends on the square of the velocity times its mass, and the mass depends on how big it is and what it's made of. So how big is 'Oumuamua, and what's its shape? Well, we can get this from its brightness. Now, if you don't believe me, think of comparing the brightness of a firefly in your backyard to the navigation lights on a distant airplane. You know the airplane is much brighter -- it just appears faint because it's so far away. We're also going to need to know how reflective the surface of 'Oumuamua is, and we don't have any clue, but it's reasonable to assume it's very similar to small asteroids and comets in our solar system, or in technical terms, something between the reflectivity of charcoal and wet sand.从非常私人的观点出发， 我们想要了解的第一件事 可能是奥陌陌的质量是多少。因为毕竟它曾经离地球非常近， 而我们发现它的时候它已经远离了。如果它撞上地球，会有多糟糕？撞击的能量 取决于速度的平方乘以它的质量， 而质量取决于它有多大， 以及由什么物质组成。那么奥陌陌有多大呢？形状又是什么样？我们能从它的亮度上来判断。如果你不相信的话， 想象一下，我们来比较两者的亮度， 一个是你后院的萤火虫 一个是远处飞机上的导航灯。飞机的灯肯定更亮， 它看起来比较暗淡是因为离得远。我们还需要知道 奥陌陌的表面反射情况， 我们没有任何线索， 但是可以有依据地猜测， 应该跟我们太阳系中的 小行星和卫星很相似。或者用技术性的描述， 它的反射率应该介于 木炭和潮湿的沙子之间。
Nowadays, most of the big telescopes are used in what's called a service mode, meaning we have to carefully develop all the instructions and send them to the telescope operator, and then anxiously wait for the data to come back, praying to the weather gods. Now I bet most of you don't have careers that critically depend on whether or not it's cloudy last night. Well, we weren't going to get any second chances here. Because the weather was great, 'Oumuamua decided not to be. Its brightness wasn't constant. Now here we see 'Oumuamua racing between the stars. It's centered in the middle. The stars are trailed out because the telescope is following its motion. It started faint and then it got brighter, fainter, brighter, and fainter again, as sunlight is reflected off of four sides of an oblong object.如今，大多数大型望远镜 都在以所谓服务模式运行， 就是说我们要仔细地准备 所有的操作流程， 然后发给望远镜操作员， 之后就是焦急地等待数据发过来， 同时向天气之神祈祷。我打赌你们都没做过这种工作， 成败与否极度依赖于头天晚上 是不是多云的天气。我们不再会有第二次机会。因为天气很不错，于是奥陌陌 给我们带来一点挑战。它的亮度不是很恒定。我们现在看到的是奥陌陌 在星星之间穿梭。它被放在了中间。星星在移动，因为望远镜 是跟着奥陌陌走的。它一会儿变暗，一会儿变亮，不停反复， 因为这个长方形物体的 四个面都会反射阳光。
The extreme brightness change led us to an unbelievable conclusion about its shape. As shown in this artist's impression, 'Oumuamua is apparently very long and narrow, with an axis ratio of about 10 to one. Assuming it's dark, this means it's about half a mile long. Nothing else in our solar system looks like this. We only have a handful of objects that even have an axis ratio bigger than five to one. So we don't know how this forms, but it may be part of its birth process in its home solar system.这种急剧的亮度变化 让我们得出了关于它形状的 非常难以置信的结论。根据艺术家制作的效果图， 奥陌陌显然又长又窄， 长短轴比差不多是10比1。假设它是黑色的， 那就意味着它有800米长。太阳系里从未有过这样的天体。我们观测到的长短轴比 超过5比1的天体 也非常少。我们不清楚它是怎么形成的， 但可能跟它在自己星系中的 形成过程有关。
'Oumuamua was varying in brightness every 7.34 hours, or so we thought. As more data started to come in from other teams, they were reporting different numbers. Why is it the more we learn about something, the harder it gets to interpret? Well, it turns out that 'Oumuamua is not rotating in a simple way. It's wobbling like a top. So while it is rotating around its short axis, it's also rolling around the long axis and nodding up and down. This very energetic, excited motion is almost certainly the result of it being violently tossed out of its home solar system. Now how we interpret the shape from its brightness depends very critically on how it's spinning, so now we have to rethink what it may look like, and as shown in this beautiful painting by space artist Bill Hartmann, we think that 'Oumuamua may be more of a flattened oval.奥陌陌的亮度 每7.34小时就发生变化， 至少我们是这么认为的。其他团队的数据陆续发来， 他们上报的数据有所不同。为什么我们对一件事情了解越多， 就越难将它解释清楚呢？事实上，奥陌陌并不是简单地在旋转。而是像陀螺一样在摇晃。它在绕自己短轴旋转的同时， 也在绕长轴翻转， 同时上下摇晃。这种有力的、激烈的运动形式， 几乎可以肯定，是因为它被猛烈地 抛出了自己的太阳系。我们如何通过它的亮度 来解释它的形状， 很大程度上取决于它的旋转方式， 因此我们不得不重新猜测它的样子， 正如太空画家比尔 · 哈特曼 这幅漂亮的画作所展示的一样， 我们认为奥陌陌可能 更像一个扁平的椭圆。
So let's get back to the energetics. What is it made of? Well, ideally we would love to have a piece of 'Oumuamua into the laboratory, so we could study it in detail. But since even private industry can't manage to launch a spacecraft within a week to something like this, astronomers have to rely on remote observations. So astronomers will look at how the light interacts with the surface. Some colors may get absorbed, giving it a chemical fingerprint, whereas other colors may not. On the other hand, some substances may just reflect more blue or red light efficiently. In the case of 'Oumuamua, it reflected more red light, making it look very much like the organic rich surface of the comet recently visited by the Rosetta spacecraft. But not everything that looks reddish has the same composition. In fact, minerals that have tiny little bits of iron in the surface can also look red, as does the dark side of Saturn's moon Iapetus, shown in these images from the Cassini spacecraft. Nickel-iron meteorites, in other words, metal, can also look red. So while we don't know what's on the surface, we know even less about what's on the inside. However, we do know that it must at least be strong enough to not fly apart as it rotates, so it probably has a density similar to that of rocky asteroids; perhaps even denser, like metal.让我们说回它的能量。它是由什么构成的？当然，最理想的方式是 我们能拿到一片奥陌陌的样本， 送到实验室仔细研究。但是即便是私人企业也无法在一周内 发射宇宙飞船， 飞往这样一个目标， 天文学家们不得不依靠遥控观测， 他们观察光线如何与表面互动。有些颜色的光线可能会被吸收， 给它留下一个化学指纹， 而其他的颜色则不会。换句话说，有些物体 会反射更多蓝色的光 或者红色的光。而奥陌陌，会反射更多的红光， 使它看起来很像罗塞塔号 最近造访的那颗彗星 富含有机物的表面。但并不是所有看起来 发红的物体都有相同的成分。实际上，表面含有少量铁的矿物质 看起来也是红色的， 就像土星的卫星伊阿珀托斯的暗面， 从卡西尼号航天器 拍下的照片中就可以看出来。镍铁陨石，换句话说，就是金属， 也可能呈红色。既然我们无法得知表面有什么， 就更无从知晓 它的内部由什么构成了。但我们至少确定它足够坚固 才不会在旋转中解体， 因此它的密度 应该跟石质的小行星类似， 也许更大，接近金属。
Well, at the very least, I want to show you one of the beautiful color images that we got from one of the ground-based telescopes. All right, I admit, it's not all that spectacular.至少，我想给大家看一眼 我们的一架地基天文望远镜 拍到的一张漂亮的彩色照片。好吧，我承认，并没有那么漂亮。
(Laughter)（笑声）
We just don't have the resolution. Even Hubble Space Telescope doesn't present a much better view. But the importance of the Hubble data was not because of the images, but because it extended our observations out to two and a half months from the discovery, meaning we get more positions along the orbit, which will hopefully let us figure out where 'Oumuamua came from.分辨率不够高。即便是哈勃太空望远镜 也无法拍得更好。但是哈勃提供的数据的重要性， 并不在于它拍摄的照片， 而是它将我们的观察期 延长到了自发现起的2个半月， 意味着我们能获得它 轨道的更多位置， 也就有希望弄清楚奥陌陌来自哪里。
So what exactly is 'Oumuamua? We firmly believe it's likely to be a leftover archaeological remnant from the process of the birth of another planetary system, some celestial driftwood. Some scientists think that maybe 'Oumuamua formed very close to a star that was much denser than our own, and the star's tidal forces shredded planetary material early in the solar system's history. Still others suggest that maybe this is something that formed during the death throes of a star, perhaps during a supernova explosion, as planetary material got shredded.那么，奥陌陌到底是什么？我们坚信，它应该是另一个行星系统 在诞生时留下的遗迹， 一些天体漂流木。有些科学家认为， 奥陌陌在形成的时候 离一颗恒星非常近， 这颗恒星比太阳密度要大， 在它形成的早期，潮汐力将 许多行星物质撕裂了。而另一些人认为， 奥陌陌也许诞生于 某颗恒星生命的晚年， 也许是在超新星爆发阶段， 行星物质被撕碎。
Whatever it is, we believe it's a natural object, but we can't actually prove that it's not something artificial. The color, the strange shape, the tumbling motion could all have other explanations. Now while we don't believe this is alien technology, why not do the obvious experiment and search for a radio signal? That's exactly what the Breakthrough Listen project did, but so far, 'Oumuamua has remained completely quiet.无论原因是什么， 我们都相信它是自然形成的， 但我们也无法证明它不是人造的。它的颜色，奇怪的形状， 翻滚的动作模式， 都有可能完全是另一种解释。既然我们不相信 这是外星人的技术， 那为什么不做个简单的实验， 搜索一下无线电信号呢？这就是“突破监听计划”在做的， 但到目前为止， 奥陌陌依然是静默状态。
Now could we send a spacecraft to 'Oumuamua and answer this question once and for all? Yes, we do actually have the technology, but it would be a long and expensive voyage, and we would get there so far from the Sun that the final approach trajectory would be very difficult.那我们能不能发射 一艘宇宙飞船去追赶奥陌陌， 一次性搞清楚所有的问题呢？没错，从技术上来说完全可行， 但这将是一场漫长而昂贵的远航， 我们会离开太阳非常远， 计算最后的对接轨道将非常困难。
So I think 'Oumuamua probably has many more things to teach us, and in fact there might be more surprises in store as scientists such as myself continue to work with the data. More importantly, I think this visitor from afar has really brought home the point that our solar system isn't isolated. We're part of a much larger environment, and in fact, we may even be surrounded by interstellar visitors and not even know it. This unexpected gift has perhaps raised more questions than its provided answers, but we were the first to say hello to a visitor from another solar system.因此我觉得，奥陌陌 还可以教我们很多事情， 事实上，随着包括我在内的 科学家们继续研究数据， 应该还有更多惊喜在等着我们。更重要的是，这位远道而来的访客 证明了一点，我们的太阳系 并不是孤立的。我们是一个更大世界的一部分， 实际上，我们周围 可能有许多星际访客， 而我们还没有察觉。这件意外的礼物 带来的疑问可能 比它解答的问题还要多， 但我们是第一批对来自 其他星系的客人打招呼的人。
Thank you.谢谢大家。
(Applause)（掌声）
Jedidah Isler: Thanks, Karen. I of course enjoyed that talk very much. Thank you. As I recall, we found it pretty late in its journey towards us. Will future technologies like the Large Synoptic Survey Telescope help us detect these things sooner?吉迪达 · 伊斯勒：谢谢凯伦。我非常喜欢这次演讲，谢谢你。我回顾了一下演讲内容，我们 发现它的时候已经非常晚了。未来的科技，比如 大型综合巡天望远镜， 是否能帮我们更早一点 发现这样的物体呢？
Karen Meech: Yeah. We're hoping that we'll start to see a lot of these things, and ideally, you'd love to find one as it's approaching the Sun, because you want to have time to do all the science, or even more ideal, you'd get a spacecraft ready to go, parked somewhere in the L4 or L5 position, somewhere near Earth, so that when something comes by, you can chase it.凯伦 · 梅赫：是的，我们希望 能发现很多这样的天体， 理想的是，最好能有一颗 正在向太阳靠近， 这样就有时间来进行研究， 更理想的是， 有一艘飞船时刻准备着， 停在L4或者L5的位置， 靠近地球， 这样如果有东西飞过， 就能进行追踪。
I am an astrobiologist interested in understanding how the ingredients that make a world habitable are delivered to terrestrial planets in their host star’s habitable zone. In particular, I am interested in understanding the distribution of volatiles in the early solar system, and how water was delivered to Earth.
I’m involved in large international collaborations both for research and graduate and early career field training. I recently led the characterization of the first interstellar object – discovered by PanSTARRS.
I believe that the key to innovative science involves interdisciplinary research, and I lead theUHNAIAstrobiology research team at UH.