系外行星搜寻者不再只是寻找新行星，而开始试图了解它们的外貌，以及是否有表面或次表面活动。

撰稿/播音：朱莉娅·罗森（Julia Rosen）

翻译：姜帆

审校：杨枭

In the last few decades, astronomers have discovered thousands of exoplanets orbiting other stars. Now, scientists want to know what they look like. Do they have oceans? Atmospheres? Researchers have even searched for signs of plant life and the glow of alien city lights—although they haven’t found any yet.

在过去的几十年间，天文学家已经发现了数以千计的围绕其他恒星运转的系外行星。现在，科学家想知道它们的样子。它们有海洋吗？有大气吗？研究人员甚至搜寻过星球生命的迹象和外星城市灯火的光芒——虽然他们还没有发现任何东西。

“We’ve moved on from being excited about finding exoplanets to now having to get our kicks out of characterizing them.”

“我们之前会因为找到系外行星而兴奋，但现在致力于描述它们的特征了。”

Moiya McTier, a graduate student at Columbia University and the host of the podcast So You Think You Can Science.

莫伊娅·麦克蒂尔（Moiya McTier）是一名来自哥伦比亚大学的研究生，还是播客《所以你认为你可以做科研》的主播。

Last year, McTier’s advisor challenged her to find something else on exoplanets: evidence of extraterrestrial mountains. Because mountains could offer clues about what’s going on inside these planets.

去年，麦克蒂尔的导师给了她一个难题，让她去寻找系外行星上的其他东西：比如外星山脉的迹象。因为山脉可以为星球内部发生的事情提供线索。

“The way that those form is through the collision of tectonic plates or through lava building up in the same place over millions of years. And so that’s one of the most exciting things, in my opinion, that can come out of this project, is actually being able to figure out what’s underneath the surface of an exoplanet.”

“在几百万年间，构造板块相互碰撞、熔岩反复侵蚀形成了这些山脉的走势。这是我觉得可以从这个项目中获得的最令人兴奋的事情之一，它实际上能够找出系外行星地表下面的东西。”

The trick was how to do it. Modern telescopes are powerful, but they can’t capture pictures of exoplanets. Instead, a common way astronomers detect them is by watching as they pass in front of their star, blotting out some of the light. McTier riffed on this idea to find a way to look for mountains.

“诀窍是如何来找。现代望远镜很强大，但它们无法捕捉系外行星的照片。但是，当这些行星经过恒星时，会遮挡恒星的光线，天文学家通常更习惯这时观测它们。麦克蒂尔从这个想法中找到了寻找山脉的办法。”

“And so, what we are doing with this mountains project is saying, okay, if a planet has a mountain on it and if that planet is rotating, then the mountain will show up in silhouette. And the silhouette will change, because the planet’s rotating. So, we can study that changing silhouette—that changing shadow—to get an idea of what the surface of the planet looks like.”

“我们在这个山脉项目中正在做的是说，如果一个星球上有一座山而且这个星球在旋转，那么这座山就会出现轮廓。而轮廓会因为星球正在旋转而改变。因此，我们可以研究这种不断变化的轮廓——变化的阴影——来了解这个星球的表面。”

McTier tested the technique by modeling how the rocky planets of our solar system would look through modern telescopes like the James Webb if they were far away.

如果岩石行星很遥远，麦克蒂尔会利用现代望远镜，比如詹姆斯韦伯空间望远镜，通过这些现代望远镜中我们太阳系中岩石行星的形态进行建模，以此来测试这一技术。

“And we were pretty heartbroken when found out that it wouldn’t be possible.”

“当发现这是不可能的时候，我们十分难过。”

But McTier calculated that it might be doable with something like the Extremely Large Telescope, which is currently under construction in Chile. Even this telescope probably wouldn’t be able to measure the topography of a Mars-like body if it orbited a large star like our Sun. But if that planet circled a smaller star, like a white dwarf, it would block out enough light to be detectible. The research is in the Monthly Notices of the Royal Astronomical Society. [Moyia A. S. McTier and David M. Kipping, Finding mountains with molehills: the detectability of exotopography]  

但是麦克蒂尔计算出，它可能适合于智利目前正在建设的超大望远镜。即使这个望远镜可能无法测量像火星一样的的地形，如果它围绕像我们的太阳这样的大型恒星公转。但是如果这颗行星围绕着一颗较小的星球，比如一颗白矮星，它会挡住足够的光线从而被探测到。这项研究发布于皇家天文学会月刊。

So, one day soon we may be able to confirm the existence of exoplanetary mountains. And with even better telescopes, maybe molehills. Or even moles.

因此，不久的将来我们或许能够证实系外行星上山脉的存在。而且有了更好的望远镜，甚至可以检测小土丘。甚至是鼹鼠。