今天NASA 发现第十颗行星。这次是真的,比冥王星还大的!
振奋人心啊!!!!!
这几个人我认识的。发现行星、小行星是他们的专长。刚才看了 Mike Brown 的网站。他是个三星期的新爸爸。真为他高兴。
Date: Fri, 29 Jul 2005 19:20:14 -0400 (EDT)
From: NASANews@hq.nasa.gov
To: undisclosed-recipients: ;
Subject: NASA SCIENTISTS DISCOVER TENTH PLANET
Dolores Beasley
Headquarters, Washington July 29, 2005
(Phone: 202/358-1753)
Jane Platt
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0880)
RELEASE: 05-209
NASA SCIENTISTS DISCOVER TENTH PLANET
A planet larger than Pluto has been discovered in the outlying regions of the solar system.
The planet was discovered using the Samuel Oschin Telescope at Palomar Observatory near San Diego, Calif. The discovery was announced today by planetary scientist Dr. Mike Brown of the California Institute of Technology in Pasadena, Calif., whose research is partly funded by NASA.
The planet is a typical member of the Kuiper belt, but its sheer size in relation to the nine known planets means that it can only be classified as a planet, Brown said. Currently about 97 times further from the sun than the Earth, the planet is the farthest-known object in the solar system, and the third brightest of the Kuiper belt objects.
"It will be visible with a telescope over the next six months and is currently almost directly overhead in the early-morning eastern sky, in the constellation Cetus," said Brown, who made the discovery with colleagues Chad Trujillo, of the Gemini Observatory in Mauna Kea, Hawaii, and David Rabinowitz, of Yale University, New Haven, Conn., on January 8.
Brown, Trujillo and Rabinowitz first photographed the new planet with the 48-inch Samuel Oschin Telescope on October 31, 2003. However, the object was so far away that its motion was not detected until they reanalyzed the data in January of this year. In the last seven months, the scientists have been studying the planet to better estimate its size and its motions.
"It's definitely bigger than Pluto," said Brown, who is a professor of planetary astronomy.
Scientists can infer the size of a solar system object by its brightness, just as one can infer the size of a faraway light bulb if one knows its wattage. The reflectance of the planet is not yet known. Scientists can not yet tell how much light from the sun is reflected away, but the amount of light the planet reflects puts a lower limit on its size.
"Even if it reflected 100 percent of the light reaching it, it would still be as big as Pluto," says Brown. "I'd say it's probably one and a half times the size of Pluto, but we're not sure yet of the final size.
"We are 100 percent confident that this is the first object bigger than Pluto ever found in the outer solar system," Brown added.
The size of the planet is limited by observations using NASA's Spitzer Space Telescope, which has already proved its mettle in studying the heat of dim, faint, faraway objects such as the Kuiper-belt bodies. Because Spitzer is unable to detect the new planet, the overall diameter must be less than 2,000 miles, said Brown.
A name for the new planet has been proposed by the discoverers to the International Astronomical Union, and they are awaiting the decision of this body before announcing the name.
For more information see:
http://www.gps.caltech.edu/~mbrown
For information about NASA and agency programs on the Web, visit:
http://www.nasa.gov/home/index
- Re: 【天文】NASA 发现第十颗行星(真的,比冥王星还大的!)posted on 07/30/2005
阿姗,我有个问题想问你
天上的星星,是怎样的?
我一直不相信自己的眼睛,她们是如何被镶进我们的眼睛?
仰望夜空,不尽的繁星,他们如何被描绘在纸上,照片上?
照片上的星星,和夜空看到的不一样!
一个星座原本在宇宙之中应该是三维,四维?
但照片上,画上,纸上很容易让人觉得那些组成星座的星星在同一个平面上?二维 - posted on 07/30/2005
末黑 wrote:
天上的星星,是怎样的?
天上的星星是好的!
我一直不相信自己的眼睛,她们是如何被镶进我们的眼睛?
仰望夜空,不尽的繁星,他们如何被描绘在纸上,照片上?
照片上的星星,和夜空看到的不一样!
一个星座原本在宇宙之中应该是三维,四维?
但照片上,画上,纸上很容易让人觉得那些组成星座的星星在同一个平面上?二维
一个星座里面的星星相对地球来讲,基本上应该是同距离的,在同一平面上,所以才会进退与共(这个成语用的对不对?)。 - Re: 【天文】NASA 发现第十颗行星(真的,比冥王星还大的!)posted on 07/30/2005
咦?不是说冥王星也不算一颗独立的行星,而是最外面的行星带中的一颗吗?那现在发现的这颗行星,是行星带之外的一颗属于太阳系的行星吗? - Re: 【天文】NASA 发现第十颗行星(真的,比冥王星还大的!)posted on 07/30/2005
是的。这几年找到了好多个外小行星带的小行星,是和冥王星一个类别的星体,但是,它们的大小不是小于冥王星就是无法断定,所以一直有“冥王星还算不算行星”这样“无谓”而“无聊”的争论。现在终于发现了比冥王星大的小行星了,迫使我们必须重新准确的归纳与命名这些星体。
前几年就已经算出来了,小行星带里应该有两三个大于冥王星的小行星,当前任务就是要找到它们。两年前发现一颗相当大的,轰动一时,可惜还是大不过冥王星。我很高兴冥王星终于被打出行星的行列了。 - Re: 【天文】NASA 发现第十颗行星(真的,比冥王星还大的!)posted on 07/30/2005
哎呀,那冥王星一定很悲伤的,再说这么动听的名字也不太容易轻易交出去的。
还有,他们如何能凭比冥王星大就认定它属于行星了?因为这只能说明冥王星不是第十颗行星,但不能说明新发现的这颗是第十颗行星。因此,你们有没有对行星质量的下限规定?
- Re: 【天文】NASA 发现第十颗行星(真的,比冥王星还大的!)posted on 07/30/2005
这“第十颗行星”的称呼是给拥护冥王星的人看的,只能用在新闻报道的标题里。我们(即科学家)早就明确了冥王星的小行星的身份,因为它和其它小行星带里的小行星是一种的。如果冥王星不是第九大行星,那当然就不能说这颗或其它颗是第十颗。
我认为太阳系里只有八颗大行星,内外两个小行星带,其中外行星带有好些比较大的小行星。
啦啦啦,这下要吵得热闹了。 - posted on 08/02/2005
Yahoo had an update to the original version of the story saying that the 10th planet, or the big asteroid, is actually smaller than Pluto.
http://news.yahoo.com/news?tmpl=story&cid=96&e=5&u=/space/20050729/sc_space/largenewworlddiscoveredbeyondneptune
Regardless this object is bigger or smaller than Pluto, isn't it just another rock in the main asteroid belt? Here's another old article on Pluto
http://science.nasa.gov/newhome/headlines/ast17feb99_1.htm
But it still doesn't seem to be such a big deal if the only practical siginificance of finding rocks bigger than Pluto is to strip the planet status of Pluto. True?
Could 阿姗 explain a little more?
阿姗 wrote:
今天NASA 发现第十颗行星。这次是真的,比冥王星还大的!
振奋人心啊!!!!!
这几个人我认识的。发现行星、小行星是他们的专长。刚才看了 Mike Brown 的网站。他是个三星期的新爸爸。真为他高兴。
http://www.gps.caltech.edu/~mbrown/planetlila/lila.JPG"> Date: Fri, 29 Jul 2005 19:20:14 -0400 (EDT)
From: NASANews@hq.nasa.gov
To: undisclosed-recipients: ;
Subject: NASA SCIENTISTS DISCOVER TENTH PLANET
Dolores Beasley
Headquarters, Washington July 29, 2005
(Phone: 202/358-1753)
Jane Platt
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0880)
RELEASE: 05-209
NASA SCIENTISTS DISCOVER TENTH PLANET
A planet larger than Pluto has been discovered in the outlying regions of the solar system.
The planet was discovered using the Samuel Oschin Telescope at Palomar Observatory near San Diego, Calif. The discovery was announced today by planetary scientist Dr. Mike Brown of the California Institute of Technology in Pasadena, Calif., whose research is partly funded by NASA.
The planet is a typical member of the Kuiper belt, but its sheer size in relation to the nine known planets means that it can only be classified as a planet, Brown said. Currently about 97 times further from the sun than the Earth, the planet is the farthest-known object in the solar system, and the third brightest of the Kuiper belt objects.
"It will be visible with a telescope over the next six months and is currently almost directly overhead in the early-morning eastern sky, in the constellation Cetus," said Brown, who made the discovery with colleagues Chad Trujillo, of the Gemini Observatory in Mauna Kea, Hawaii, and David Rabinowitz, of Yale University, New Haven, Conn., on January 8.
Brown, Trujillo and Rabinowitz first photographed the new planet with the 48-inch Samuel Oschin Telescope on October 31, 2003. However, the object was so far away that its motion was not detected until they reanalyzed the data in January of this year. In the last seven months, the scientists have been studying the planet to better estimate its size and its motions.
"It's definitely bigger than Pluto," said Brown, who is a professor of planetary astronomy.
Scientists can infer the size of a solar system object by its brightness, just as one can infer the size of a faraway light bulb if one knows its wattage. The reflectance of the planet is not yet known. Scientists can not yet tell how much light from the sun is reflected away, but the amount of light the planet reflects puts a lower limit on its size.
"Even if it reflected 100 percent of the light reaching it, it would still be as big as Pluto," says Brown. "I'd say it's probably one and a half times the size of Pluto, but we're not sure yet of the final size.
"We are 100 percent confident that this is the first object bigger than Pluto ever found in the outer solar system," Brown added.
The size of the planet is limited by observations using NASA's Spitzer Space Telescope, which has already proved its mettle in studying the heat of dim, faint, faraway objects such as the Kuiper-belt bodies. Because Spitzer is unable to detect the new planet, the overall diameter must be less than 2,000 miles, said Brown.
A name for the new planet has been proposed by the discoverers to the International Astronomical Union, and they are awaiting the decision of this body before announcing the name.
For more information see:
http://www.gps.caltech.edu/~mbrown For information about NASA and agency programs on the Web, visit:
http://www.nasa.gov/home/index - Re: 【天文】发现第十颗行星(真的,比冥王星还大的!)posted on 08/02/2005
Guoguo, 我刚读了这篇报道。是的,就是找到了另外一块在行星带里的大石头。冥王星也是,不过大一点,离太阳近一点,所以最先发现。
的确不是很大的“发现”,只是,如果真的发现颗大石头,就不能再说九大行星了而是八大。我觉得这件事能足够说明,科学不是绝对正确的,科学的“真理”是会不时更新的。
当然这对咖啡店的人来说是没什么了不起,但可是世界上好些人不明白。这是一个好的教育例子。 - posted on 08/03/2005
懂了, 是大石头还好些, 不然又有那四川神人连八卦都搬出来了, 真TM能蒙人.
打倒冥王星及其代表的大小石头们!
阿姗 wrote:
Guoguo, 我刚读了这篇报道。是的,就是找到了另外一块在行星带里的大石头。冥王星也是,不过大一点,离太阳近一点,所以最先发现。
的确不是很大的“发现”,只是,如果真的发现颗大石头,就不能再说九大行星了而是八大。我觉得这件事能足够说明,科学不是绝对正确的,科学的“真理”是会不时更新的。
当然这对咖啡店的人来说是没什么了不起,但可是世界上好些人不明白。这是一个好的教育例子。 - posted on 08/14/2006
Astronomers struggle to define 'planet'
By ALICIA CHANG, AP Science Writer Sun Aug 13, 8:43 PM ET
LOS ANGELES - Our solar system is suffering an identity crisis.
For decades, it has consisted of nine planets, even as scientists debated whether Pluto really belonged. Then the recent discovery of an object larger and farther away than Pluto threatened to throw this slice of the cosmos into chaos.
Should this newly found icy rock known as "2003 UB313" become the 10th planet? Should Pluto be demoted? And what exactly is a planet, anyway?
Ancient cultures regularly revised their answer to the last question and present-day scientists aren't much better off: There still is no universal definition of "planet."
That all could soon change, and with it science textbooks around this planet.
At a 12-day conference beginning Monday, scientists will conduct a galactic census of sorts. Among the possibilities at the meeting of the International Astronomical Union in the Czech Republic capital of Prague: Subtract Pluto or christen one more planet, and possibly dozens more.
"It's time we have a definition," said Alan Stern, who heads the Colorado-based space science division of the Southwest Research Institute of San Antonio. "It's embarrassing to the public that we as astronomers don't have one."
The debate intensified last summer when astronomer Michael Brown of the California Institute of Technology announced the discovery of a celestial object larger than Pluto. Like Pluto, it is a member of the Kuiper Belt, a mysterious disc-shaped zone beyond Neptune containing thousands of comets and planetary objects. (Brown nicknamed his find "Xena" after a warrior heroine in a cheesy TV series; pending a formal name, it remains 2003 UB313.)
The Hubble Space Telescope measured the bright, rocky object at about 1,490 miles in diameter, roughly 70 miles longer than Pluto. At 9 billion miles from the sun, it is the farthest known object in the solar system.
The discovery stoked the planet debate that had been simmering since Pluto was spotted in 1930.
Some argue that if Pluto kept its crown, Xena should be the 10th planet by default — it is, after all, bigger. Purists maintain that there are only eight traditional planets, and insist Pluto and Xena are poseurs.
"Life would be simpler if we went back to eight planets," said Brian Marsden, director of the astronomical union's Minor Planet Center in Cambridge, Mass.
Still others suggest a compromise that would divide planets into categories based on composition, similar to the way stars and galaxies are classified. Jupiter could be labeled a "gas giant planet," while Pluto and Xena could be "ice dwarf planets."
"Pluto is not worthy of being called just a plain planet," said Alan Boss, an astrophysicist at the Carnegie Institution in Washington, D.C. "But it's perfectly fine as an ice dwarf planet or a historical planet."
The number of recognized planets in the solar system has seesawed based on new findings. Ceres was initially classified as a planet in the 1800s, but was demoted to an asteroid when similar objects were found nearby.
Despite the lack of scientific consensus on what makes a planet, the current nine — and Xena — share common traits: They orbit the sun. Gravity is responsible for their round shape. And they were not formed by the same process that created stars.
Brown, Xena's discoverer, admits to being "agnostic" about what the international conference decides. He said he could live with eight planets, but is against sticking with the status quo and would feel a little guilty if Xena gained planethood because of the controversy surrounding Pluto.
"If UB313 is declared to be the 10th planet, I will always feel like it was a little bit of a fraud," Brown said.
For years, Pluto's inclusion in the solar system has been controversial. Astronomers thought it was the same size as Earth, but later found it was smaller than Earth's moon. Pluto is also odd in other ways: With its elongated orbit and funky orbital plane, it acts more like other Kuiper Belt objects than traditional planets.
Even so, Pluto remained No. 9 because it was the only known object in the Kuiper Belt at the time.
When new observations in the 1990s confirmed that the Kuiper Belt was sprinkled with numerous bodies similar to Pluto, some scientists piped up. In 1999, the international union took the unusual step of releasing a public statement denying rumors that the ninth rock from the sun might be kicked out.
That hasn't stopped groups from attacking Pluto's planethood. In 2000, the Hayden Planetarium at New York's American Museum of Natural History unleashed an uproar when it excluded Pluto as a planet in its solar system gallery.
Earlier this year, NASA's New Horizons spacecraft began a 9 1/2-year journey to Pluto on a mission that scientists hope will reveal more about the oddball object.
The trick for astronomers meeting in Prague is to set a criterion that makes sense scientifically. Should planets be grouped by location, size or another marker? If planets are defined by their size, should they be bigger than Pluto or another arbitrary size? The latter could expand the solar system to 23, 39 or even 53 planets.
It's not an academic exercise — the public may not be open to a flood of new planets. Despite their differences, scientists agree any definition should be flexible enough to accommodate new discoveries.
"Science progresses," said Boss of the Carnegie Institution. "Science is not something that's engraved on a steel tablet never to be changed."
____
On the Net:
International Astronomical Union: http://www.iau.org California Institute of Technology: http://www.caltech.edu Minor Planet Center: http://cfa-www.harvard.edu/iau/mpc.html - posted on 08/16/2006
Proposal would add planets to solar system
By WILLIAM J. KOLE, Associated Press Writer 1 hour, 32 minutes ago
PRAGUE, Czech Republic - The universe really is expanding — astronomers are proposing to rewrite the textbooks to say that our solar system has 12 planets rather than the nine memorized by generations of schoolchildren.
Much-maligned Pluto would remain a planet — and its largest moon plus two other heavenly bodies would join Earth's neighborhood — under a draft resolution to be formally presented Wednesday to the International Astronomical Union, the arbiter of what is and isn't a planet.
"Yes, Virginia, Pluto is a planet," quipped Richard Binzel, a professor of planetary science at the Massachusetts Institute of Technology.
The proposal could change, however: Binzel and the other nearly 2,500 astronomers from 75 nations meeting in Prague to hammer out a universal definition of a planet will hold two brainstorming sessions before they vote on the resolution next week. But the draft comes from the IAU's executive committee, which only submits recommendations likely to get two-thirds approval from the group.
Besides reaffirming the status of puny Pluto — whose detractors insist it shouldn't be a planet at all — the new lineup would include 2003 UB313, the farthest-known object in the solar system and nicknamed Xena; Pluto's largest moon, Charon; and the asteroid Ceres, which was a planet in the 1800s before it got demoted.
The panel also proposed a new category of planets called "plutons," referring to Pluto-like objects that reside in the Kuiper Belt, a mysterious, disc-shaped zone beyond Neptune containing thousands of comets and planetary objects. Pluto itself and two of the potential newcomers — Charon and 2003 UB313 — would be plutons.
Astronomers also were being asked to get rid of the term "minor planets," which long has been used to collectively describe asteroids, comets and other non-planetary objects. Instead, those would become collectively known as "small solar system bodies."
If the resolution is approved, the 12 planets in our solar system listed in order of their proximity to the sun would be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon, and the provisionally named 2003 UB313. Its discoverer, Michael Brown of the California Institute of Technology, nicknamed it Xena after the warrior princess of TV fame, but it likely would be rechristened something else later, the panel said.
The galactic shift would force publishers to update encyclopedias and school textbooks, and elementary school teachers to rejigger the planet mobiles hanging from classroom ceilings. Far outside the realm of science, astrologers accustomed to making predictions based on the classic nine might have to tweak their formulas.
Even if the list of planets is officially lengthened when astronomers vote on Aug. 24, it's not likely to stay that way for long: The IAU has a "watchlist" of at least a dozen other potential candidates that could become planets once more is known about their sizes and orbits.
"The solar system is a middle-aged star, and like all middle-aged things, its waistline is expanding," said Jack Horkheimer, director of the Miami Space Transit Planetarium in the United States and host of Public Broadcasting's Stargazer television show.
Opponents of Pluto, which was named a planet in 1930, still might spoil for a fight. Earth's moon is larger; so is 2003 UB313 (Xena), about 70 miles wider.
But the IAU said Pluto meets its proposed new definition of a planet: any round object larger than 800 kilometers (nearly 500 miles) in diameter that orbits the sun and has a mass roughly one-12,000th that of Earth. Moons and asteroids will make the grade if they meet those basic tests.
Roundness is key, experts said, because it indicates an object has enough self-gravity to pull itself into a spherical shape. Yet Earth's moon wouldn't qualify because the two bodies' common center of gravity lies below the surface of the Earth.
"People were probably wondering: If they take away Pluto, is Rhode Island next?" Binzel quipped. "There are as many opinions about Pluto as there are astronomers. But Pluto has gravity on its side. By the physics of our proposed definition, Pluto makes it by a long shot."
IAU President Ronald D. Ekers said the draft definition, two years in the making, was an attempt to reach a cosmic consensus and end decades of quarreling. "We don't want an American version, a European version and a Japanese version" of what constitutes a planet, he said.
Neil deGrasse Tyson, director of the Hayden Planetarium at New York's American Museum of Natural History — miscast as a "Pluto-hater," he contends, merely because Pluto was excluded from a solar system exhibit — said the new guidelines would clear up the fuzzier aspects of the Milky Way.
"For the first time since ancient Greece, we have an unambiguous definition," he said. "Now, when an object is debated as a possible planet, the answer can be swift and clear."
___
AP Science Writers Alicia Chang in Los Angeles and Seth Borenstein in Washington contributed to this story.
___
On the Net:
International Astronomical Union, http://www.iau.org - Re: 【天文】发现第十颗行星posted on 08/16/2006
阿姗能否提导一下怎么观察夏夜的行星?
我注意到最近天一黑顶西南天空有一颗极亮的星,还跟孩子说那是飞
机,比织女星还显亮。仔细想想,肯定是颗行亮。
在大熊座下面,牧夫武仙之间。(是阿姗的火星?)
行星我只知道一颗太白金星(启明星?),还不确定。
这第十颗行星够远的,得望远镜吗?行星比恒星难认多了。。。真的
很想多认几颗行星。
先谢了!
btw:另外,我这里有《道德经》的朗诵CD,连带七篇庄子。要的话
可以拷贝一份给你。 - Re: 【天文】发现第十颗行星posted on 08/16/2006
xw wrote:
btw:另外,我这里有《道德经》的朗诵CD,连带七篇庄子。要的话
可以拷贝一份给你。
一般常识认为,读一次道德经,看一眼道德经,要老三个月。读一遍,要变老五年。而且你自己不觉着,看不出来。别人一看,就能觉察到。要三思而行啊。:) - posted on 08/17/2006
不懂星空啊。可以弄本天文杂志看看。以前我经常到老板办公室去看他杂志上的星图。网上也有,我看不懂。
以前见过很亮很亮的,是太空站。可以在网上查到太空站座标的。
会不会是金星?我现在每天太阳一落就躲在家里,更不知道你说的是哪个了。一般来说,日落日出前后的就是金星。
行星很简单,肉眼见到的就那几颗(金木水火土),不是每天都能看到所有的,知道这个月能看到哪个,就容易找了。一般比恒星亮,而且不那么一闪一闪的。
刚才随便查了一下,见到流星雨 The PERSEIDS (August 12) may be washed out by Moonshine (not the drink!) this year. http://www.astronomytoday.com/skyguide.html
朗诵 CD 好啊。谢谢!道德经大概我不需要再读了,已经批准了,所以令胡冲不用为我担心。庄子要读一读,以前很喜欢的,应该会阅读越年轻。哪天灵感来了,也给翻译一回。
我的研究生导师前几年搞了一大套讲老子的磁带,好几十个小时,是个台湾老太太讲的。我老师给推荐了很久。那时我对这个没兴趣。两年前为了追男人才去看道德经,发现无穷天地。爱情的力量是不可忽视的。
十二行星图:
十二是个好数字。8, 9, 10 都好。可能因此,故意把 11 跳过去了。 - Re: 【天文】发现第十颗行星posted on 08/17/2006
今天观察了两个小时,从网上次料来看,应该是木星。
http://currentsky.com/planetwatch.html
我只用肉眼看的。
提着手电筒,一个人跑到山顶上。
&&&
令胡对老子的感慨,有如鲁迅。阿姗,庄子的CD要不要呢,只有七篇?
只读经,不讲废话的。
- Re: 【天文】发现第十颗行星posted on 08/17/2006
木星应该对了。金星是最亮的,金色的,不会看错。其它行星只有木星有可能非常亮。剩下的多数情况下都比恒星暗。
老子庄子都要。一张CD就够了,是吧?不想你太麻烦。 - Re: 【天文】发现第十颗行星posted on 08/17/2006
xw wrote:
btw:另外,我这里有《道德经》的朗诵CD,连带七篇庄子。要的话
可以拷贝一份给你。
有没有可能麻烦 xw 把它上到网上什么地方,我们都可以下栽?还是这样做不好?
反正也老了,不怕更老 :) - posted on 08/18/2006
War of the Worlds (from The New York Times)
By MIKE BROWN
Published: August 16, 2006
Pasadena, Calif.
LAST year, two colleagues and I announced that we had found an unknown body slightly larger than Pluto in the far reaches of our solar system. Since then, astronomical confusion has reigned on Earth and, depending on whom you ask, our solar system has 8, 9, 10 or, shockingly, 53 planets.
Next week, the International Astronomical Union, which oversees astronomical rules and conventions, will vote on a strict definition of “planet.” The result of that vote is hard to predict, but soon, we’ll likely lose a planet we’ve gotten to know for the past 76 years, or gain at least one more.
From a scientific point of view, the status of Pluto and the newly discovered object — stuck with the cumbersome label 2003 UB313 until astronomers decide what it is — is easy to discern. If you were to look unemotionally at the hundreds of thousands of bodies orbiting the sun, only eight (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) would clearly distinguish themselves by their large sizes.
The remaining objects, which are significantly smaller, are mostly either rocky bodies in the asteroid belt between Mars and Jupiter or icy bodies in the Kuiper Belt in the distant regions beyond Neptune. Of the more than 1,000 known objects in the Kuiper Belt, 2003 UB313 and Pluto are the largest and second largest.
So why is there any debate at all, if the scientific view is so clear?
It all dates back to the discovery of Pluto in 1930. At the time, Pluto was thought to be considerably larger than it is now known to be, and the existence of the rest of the Kuiper Belt was unknown. No other reasonable category existed in which to place the object, so Pluto became the oddball planet at the edge of the solar system.
Since then, Pluto has been very much a part of our mental map of the universe. You’ll find it on lunchboxes, postage stamps, NASA Web sites, and in the mnemonics that children learn to remember the planets. Pluto’s qualifications may be more cultural than scientific, but we’ve fully embraced it as a planet in good standing.
This is why astronomers who question Pluto’s status come across as bullies trying to kick everyone’s favorite cosmic underdog out of the club. And while they have a point — after all, it’s not a great idea to let cultural attachments dictate scientific categories — they’re missing an important part of the picture.
Think of it this way. The term “planet” is similar to “continent.” The word helps us organize our world, but the division between continents and subcontinents is thoroughly arbitrary. Yet no union of geologists has tried to vote on a definition of “continent,” and no one is concerned that letting culture determine the difference between Australia, the smallest continent, and Greenland, the largest island, somehow erodes science.
Like continents, planets are defined more by how we think of them than by someone’s after-the-fact pronouncement.
How then should we think about 2003 UB313? I’m biased, but I like to imagine this question through the eyes of the child I was in the 1970’s, when astronauts had just walked on the Moon, the first pictures were coming back from the surface of Mars and the launch of Skylab promised a future of unbroken space exploration.
If I had heard back then about the discovery of something at the edge of the solar system, I wouldn’t have waited for a body of astronomers to tell me what it was. I would have immediately cut out a little disk of white paper and taped it to the poster of planets on my bedroom wall. That night, I would have looked up, straining to see the latest addition to our solar system, hoping that I, too, might someday find a new planet.
Recently, many plans for exploration and scientific study have been scrapped, and those that haven’t are being scaled back. It’s hard to have the same excitement about a limitless future in space.
The astronomical union isn’t helping matters by forcing a Hobson’s choice: stick with the current nine planets or open the floodgates to a yawn-inducing 53 or more. It’s a “No Ice Ball Left Behind” policy.
I hope the union takes another galactic approach, and simply declares 2003 UB313 our 10th, full-fledged planet. Doing so might convince schoolchildren to put new paper disks on their walls, to look up to the sky and realize that exploration does continue, and that they can be part of it, too.
Mike Brown is a professor of planetary astronomy at the California Institute of Technology.
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Brown seems a bit less "agnostic" to me here. Or is it simply: science changes, scientist too? - Re: 【天文】发现第十颗行星posted on 08/19/2006
浮生 wrote:
xw wrote:有没有可能麻烦 xw 把它上到网上什么地方,我们都可以下栽?还是这样做不好?
btw:另外,我这里有《道德经》的朗诵CD,连带七篇庄子。要的话
可以拷贝一份给你。
反正也老了,不怕更老 :)
回浮生阿姗,网上下载,我不会搞。拷贝CD倒也容易,两张盘。阿姗
就用玛雅上回用的地址?浮生能否把地址寄到我的信箱?
这第十颗行星无所谓,我村里人都认得木星了,这个顶重要!
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