密歇根新闻广播 矮行星的发现可能将宇航员带往新的星球

 

We're learning a lot about our tiny corner of the cosmos¹ these days. That's thanks to improving technology and the increasing number of probes we're sending into the solar system.

But as much as we learned so far, there's still a lot about space that we don't know.

Recently, researchers have been trying to track down a theoretical Planet Nine. (That's the title formerly² held by Pluto³. Sorry, Pluto.)

University of Michigan astronomers⁴ recently came across a planetary surprise that might get us closer to that discovery. And it turns out Pluto might have a friend out there after all.

Astronomy professor David Gerdes sat down with us today to talk about an object that caught his team's eye in the distant reaches of the solar system.

"We've found what we think is a dwarf⁵ planet, a small minor⁶ planet that's orbiting in the solar system beyond Neptune⁷, far, far, far beyond Pluto," Gerdes said.

The object was given the designation 2014 UZ224 by the Minor Planet Center. An official name can be proposed after its orbit has been observed and refined for several more years, but for now the team is calling it "DeeDee." That's short for "distant dwarf."

Gerdes told us DeeDee is more than twice as far away from Earth and the sun as Pluto. That puts it somewhere in the ballpark of 8.5 billion miles from the sun.

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The team estimates DeeDee is a little over 320 miles in diameter, which is "right at the border line for dwarf planethood."

According to Gerdes, there's no doubt DeeDee exists, but it's less certain whether or not it's truly a dwarf planet.

"This was found with a ground-based telescope, not with a space probe," he said.

This wasn't your garden variety hobby spyglass, though. The telescope is four meters in diameter.

Gerdes' team didn't set out to find any new planets. They were looking to map distant galaxies⁸ in order to understand more about the large scale structure and expansion of the universe.

"Although our goal is to look at distant galaxies, we're looking out through the dusty window of our solar system and there's stuff in the foreground that gets in the way," he said.

Gerdes told us that DeeDee is cool not because it's special or unique, but because it might not be.

"To me the interesting thing about it is that [dwarf planets like DeeDee] are probably fairly common. There are probably many more of them, and there may be an even bigger prize out there," he said.

The thought is that the techniques and technology Gerdes and his team developed to pick out these incredibly faint, mind-bogglingly distant objects could help in the search for a ninth planet.

"Planet Nine was motivated by the idea that if you look at the trans-Neptunian objects with the very longest periods, even longer than DeeDee, objects that take thousands of years to go around the sun, they follow along elliptical orbits like DeeDee too," Gerdes said. "But there's a special thing about those orbits. The ellipses⁹ line up in the same direction. They're long, skinny things that all point one way, as though they are under the influence of a yet even more distant massive object that's pulling those objects to one side. The shorter-period objects don't do that, they're random¹⁰. But if you look at the longest-period ones, they seem to be under the influence of something else."

Gerdes told us that Planet Nine's orbit has been worked out, but it's unknown where along its orbit the planet might currently be.

"What we know is a band on the sky where Planet Nine might be," he said. A portion of that band intersects with the part of the sky that Gerdes' survey is looking at.

"If Planet Nine happens to be in there, I believe it is bright enough to show up in our data, and in the next year or so we'll know if it's there or not," he said. "It's a matter of months to a year, not decades."

In our conversation above, Gerdes talks more about Planet Nine and how his team discovered DeeDee.

1 cosmos   

n.宇宙；秩序，和谐

参考例句：

• Our world is but a small part of the cosmos.我们的世界仅仅是宇宙的一小部分而已。
• Is there any other intelligent life elsewhere in the cosmos?在宇宙的其他星球上还存在别的有智慧的生物吗？

2 formerly   

adv.从前，以前

参考例句：

• We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
• This boat was formerly used on the rivers of China.这船从前航行在中国内河里。

3 Pluto   

n.冥王星

参考例句：

• Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
• Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。

4 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

5 dwarf   

n.矮子，侏儒，矮小的动植物；vt.使…矮小

参考例句：

• The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
• The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀，摇摇头。

6 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

7 Neptune   

n.海王星

参考例句：

• Neptune is the furthest planet from the sun.海王星是离太阳最远的行星。
• Neptune turned out to be a dynamic,stormy world.海王星原来是个有生气、多风暴的世界。

8 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

9 ellipses   

n.椭园，省略号；椭圆( ellipse的名词复数 )；（语法结构上的）省略( ellipsis的名词复数 )

参考例句：

• The planets move around the sun in ellipses. 各行星围绕太阳按椭圆形运转。 来自《简明英汉词典》
• Summations are almost invariably indicated ellipses instead of the more prevalent sigma notation. 在表示“连加”的式子中，几乎一成不变地使用省略号来代替更为流行的“∑”符号。 来自辞典例句

10 random   

adj.随机的；任意的；n.偶然的(或随便的)行动

参考例句：

• The list is arranged in a random order.名单排列不分先后。
• On random inspection the meat was found to be bad.经抽查，发现肉变质了。