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人类可能发现了首颗系外卫星! – 译学馆
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人类可能发现了首颗系外卫星!

We May Have Found the First Exomoon! | SciShow News

[♩进场音乐]
[♩INTRO]
距离天文学家发现
It’s been more than 20 years
第一颗绕除太阳以外的恒星运行的行星
since astronomers discovered the first planet
已经过去了二十多年
orbiting a star beyond our own.
如今 收录在册的系外行星数目超过了3700个
And today, there’s a catalog of more than3700 confirmed exoplanets,
而且还有数以千计的“候选者”
along with thousands more unconfirmed candidates.
如今 我们发现了在太阳系之外的
But now, we might have found the very first moon
第一颗卫星
beyond our solar system,
或系外卫星
or an exomoon.
上周 科学前沿杂志发表了关于它存在的”无可争辩”的证据
Last week, Science Advances published thefirst quote-unquote
这颗距我们8000光年以外的卫星和海王星一样巨大
“compelling evidence” of a huge, Neptune-sized exomoon 8,000 light-years away.
在2017年
In 2017, data
开普勒太空望远镜就开始注意到这颗系外卫星
from the Kepler Space Telescope seemed to contain hints that an
可能存在
exomoon might be out there.
数据表明:一颗巨大的气体天体
The data revealed that a body, the size ofa gas
正绕着一个更大的被称为开普勒-1625b的天体转
giant, was orbiting a larger body called Kepler 1625b. Now,
两位哥伦比亚大学的天文学家使用更清晰的
two astronomers from Columbia Universityhave used the even-stronger
哈勃太空望远镜来对它进行进一步的观测
Harbor Space Telescope to further explorethe system.
据他们说 观测结果显示系外卫星
And from what they saw, it looks like thatexomoon signature
并不是数据中的错误
isn’t some error in the data.
在最新的研究中 这个团队采用了凌日时间变分法来研究1625b行星
In the new study, the team used the transit method to study 1625b.
换句话说 他们研究
In other words, they analyzed the light coming
当这颗行星穿过恒星和我们之间时
from its star and how it dims
恒星发出的光及其明暗变化的规律
as the planet passes between the star andus.
奇怪的是
The weird thing was,
凌日后的3.5小时
about 3.5 hours after the planet’s transit ended, there was
恒星亮度有一个稍小的下降
a smaller dip in brightness.
那暗示那个行星有一个卫星跟着它
That suggests the planet has a moon trailingit.
让天文爱好者(包括我们)感到遗憾的是
To the disappointment of space nerds everywhere(including us) the team
在这颗疑似卫星结束自己的凌日过程前团队的观测时间不够了
ran out of observation time before the potential moon had finished its own transit.
因此他们没有获取完整的分析数据
So they don’t have a full set of data toanalyze.
值得庆幸的是 还有一点数据
But the good news is, there is a little more data
可以支持这颗行星有自己的天然卫星的说法
that supports the planet having a naturalsatellite:
行星凌日的过程比预计的早了1个小时
The planet’s transit started over an hourearlier than was predicted.
因为如果行星有卫星牵引着它 并且系统的引力中心有偏移
That could happen if it had a moon tuggingon it
那么上面的提到现象是可能出现的
and changing the system’s center of gravity.
至此 如果这个卫星真的存在 以上所有的证据可以证明
So far, all this evidence suggests this moon,if it exists,
这颗卫星的质量和体积与海王星相当
is comparable in mass and size to Neptune.
以我们的标准看 那非常大
By our standards, that’s huge.
但是因为那颗行星的体积和木星差不多大
But since the planet is around the same sizeas Jupiter
质量也是木星的几倍 所以上面的观测就说得通了
and a few times more massive, it makes sense.
再次声明 以上这些性质不是基于最可靠的模型推演而得
Then again, these properties aren’t basedon the strongest models,
所以仍然存在不确定性
so there’s still some uncertainty.
可能是数据的偏差
It could be that our data is a bit off and
或许这颗卫星其实并不存在
that there isn’t a moon at all. Instead,
而相反 这个系统里
there could be a second planet
也可能存在另一颗行星
in the system that’s responsible,
但至今没有任何证据证明这一点
although there hasn’t been any evidenceof that so far.
还有一个可能 1625b的
It’s also possible that 1625b could justhave
公转周期比我们想象的更长
a longer orbital period than we think.
又或者它公转的距离太远或者角度太大
Or it could be orbiting at such a distance or angle
以至于每次我们看它时
that it’s not transiting every
它并不是处在凌日的过程中
time we look at it,
因此 我们这次的的预测出现了偏差
which could be why our predictions were off this time.
现在 本文的作者也表示
Right now, the authors
这第一个发现的系外卫星在证实其存在之前 需要
of this paper confess this first exomoon has to survive
多年的审查和后续的观测
years of scrutiny and follow-up before itsexistence can be confirmed.
但是如果它最后真的
But if it does end up
被证实是我们太阳系外的一颗卫星
being a moon beyond our solar system,
那它会是一个非常重要的对象 值得继续研究
it will be a really important target to continuestudying.
比如 因为它似乎
For example, since it’s likely much,
比我们太阳系中的任何卫星都要大
much larger than any moon in our system,
这引发我们去追问行星系统是如何形成和演化的
it opens the question of how planetary systemsform and evolve.
但此刻 卫星的起源完全是个谜
But at the moment, the moon’s origins area total mystery. Like,
比如 它是被行星捕获 还是和行星一同形成 我们无法确定
was it captured, or did it form alongsideits partner?
此刻 我们只能猜测
At this point, we can only guess.
在另一个关于卫星的新闻
In other moon news,
一篇通过网络在自然地理科学上发布的论文中
a study published online this week in Nature Geoscience
推测木卫二 木星的一个较大的卫星
predicts a decent chunk of Jupiter’s moonEuropa
很可能被巨大的刀刃状的冰覆盖!
might be covered in giant ice blades! Officially,
官方称之为penitentes
these blades are called penitentes.
当大量的冰块
They’re formed when large chunks
受热升温时
of frozen water heat up and sublimate,
水从固态直接变成气态 就会形成冰刃
turning directly from a solid into a gas.
在地球的许多地方可以看到类似的情况
On Earth, we see this happen in places
比如安第斯山脉的山顶
like the top of the Andes Mountains.
但是我们在冥王星上也能看到这些
But we’ve also seen evidence of these bladeson Pluto.
要形成冰刃
For penitentes to form,
环境需要非常非常干燥和寒冷
the environment has to be super dry and cold,
空气也要静止不动
the air has to be really still,
并且阳光要以合适的角度
and the sunlight has to hit the ice
照到冰上 持续足够长的时间
at just the right angle and for long enough periods of time. Then,
然后阳光的照射让水分子升华
the Sun’s radiation causes heaps ofwater molecules to sublimate,
在冰面形成深深的凹陷 使得冰的外形非常尖锐
carving deep depressions into the surfaceand turning everything really spiky.
换言之 冰刃不像石笋那样生长
In other words, the penitentes don’t growup like stalagmites do
它们是冰块生化剩下的
they’re leftovers! Eventually,
最终 冰刃会因为地下的地质活动
penitentes smooth out or breakapart,
或者来自上方宇宙残骸的冲击
either from geologic activity beneath thesurface or space debris
而被弄平或者破裂
smashing into them from above.
但是 耗费的时间会有所不同
But the amount of time that takes can vary.
为了更多地了解木卫二
To learn more about Europa, astronomers wantedto determine the likelihood, location,
天文学家想确定它们的位置 形成几率
and size of penitentes.
因此 他们建立了一个模型
So they created a model.
这个模型里考虑到许多因素
It took into account things
比如木卫二对太阳的倾斜程度
like how Europa is tilted toward the Sun,
温度范围以及表面的反射率
its range of temperatures, and the reflectivityof its surface.
他们还需要估算
They also needed to estimate how
宇宙残骸冲击木卫二的频率
often space debris would crash into
因为这些冲击会磨平它们
Europa’s surface, which would smooth outits features.
根据他们的模型 在纬度大约23°的地方
According to their model, water could sublimatefaster than erosion could
水的蒸发会比侵蚀快
smooth things out at latitudes below 23°or so
这意味着 木卫二的赤道存在一个宽大的区域
That means, for a large band around Europa’sequator,
区域内存在大量完好的penitente
we’d likely see a healthy population ofpenitentes.
团队还计算出:超过5千万年
The team also calculated that, over 50 millionyears
(木卫二的表面的平均年龄也是5千万年)
which is the average age of Europa’s surface
刀刃状的冰可以达到15米
the blades could get up to 15 meters tall.
这可比我们在地球上常看到的penitente的三倍还高
That’s three times taller than what we usuallysee on Earth.
当然 所有的状态都是平均值
Of course, all their status are averages,
也没有将
and don’t take into account local
地质特性 冰的纯度的影响考虑进来
geologic features, or exactly how impurities in the ice will play a role.
所以 还有许多仍待研究
So there may be more to the story. Unfortunately,
不幸的是 依靠我们的技术靠近木卫二
our technology near Europadoesn’t have the proper resolution
也无法获得足够清晰度的照片来证实这些刀刃状的表面
to find photographic evidence of this spikysurface.
但是 有地表雷达和热量数据
But there is both ground-based radar and thermaldata
从上世纪90年代的伽利略号探测器的观测结果看 penintente可能存在
from the 1990s Galileo probe that suggestspenitentes could be there.
这样的研究非常酷
Studies like this are cool,
但是这些研究不仅仅是揭示了
but they’re about more than just uncovering giant ice
在遥远的卫星上的巨大尖锐的冰川
spikes on a far-flung moon.
对科学家和工程师而言 这类信息
To scientists and engineers, this kind ofinformation is really important
对于未来的木卫二登陆计划至关重要
to know when planning a future lander missionto Europa.
这颗卫星是
The moon is one
科学家确认的表面以下存在液态水海洋的
of a few that scientists are almost definitely sure has a liquid
众多行星中的一颗
water ocean beneath its surface.
虽然现在没有任何登陆探测器
And although there aren’t
被正式写入计划表中
any landers officially on the docket right now,
但当我们有能力的时候
we’ll need all the information we
我们会需要这些信息
can get when we are ready to go.
感谢观看本集的SciShow宇宙新闻
Thanks for watching this episode of SciShowSpace News!
也非常感谢Patreon上的赞助者们
And thanks especially to our Patrons on Patreon.
地球以外的东西是那么美丽且令人着迷
The things beyond our planet are beautifuland fascinating,
我们希望和你们一起探索
and we love getting to explore them with you.
[♩退场音乐]
[♩OUTRO]

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视频概述

人类首次发现太阳系外的卫星,木卫二上存在奇特的冰块。

听录译者

收集自网络

翻译译者

Jason Li

审核员

审核员 LD

视频来源

https://www.youtube.com/watch?v=7PDlsn9TH8c

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