卡西尼拍摄的最新土星绚彩光环！
丰富多彩的颜色和异常奇异的层次感让我们大开眼界。。。::0020:: ::0024::好久没在这里贴图了，爆一个先！
来自：
http://www.jpl.nasa.gov/news/news.cfm?release=2007-062
Cassini 'Cat Scan' Maps Clumps in Saturn's Rings
May 22, 2007
Saturn's largest and most densely packed ring is composed of tightly packed clumps of particles separated by nearly empty gaps, according to new findings from NASA's Cassini spacecraft.
These clumps in Saturn's B ring are neatly organized and constantly colliding, which surprised scientists.
"The rings are different from the picture we had in our minds. We originally thought we would see a uniform cloud of particles. Instead we find that the particles are clumped together with empty spaces in between," said Larry Esposito, principal investigator for the Cassini ultraviolet imaging spectrograph at the University of Colorado, Boulder. "If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth. This is different from flying under a uniform cloud of particles."
Because previous interpretations assumed the ring particles were distributed uniformly, scientists underestimated the total mass of Saturn's rings. The mass may actually be two or more times previous estimates.
"These results will help us understand the overall question of the age and hence the origin of Saturn's rings," said Josh Colwell, assistant professor of physics at the University of Central Florida, Orlando, and a team member of the Cassini ultraviolet imaging spectrograph. A paper with these results appears in the journal Icarus.
Scientists observed the brightness of a star as the rings passed in front of the star on multiple occasions. This provided a measurement of the amount of ring material between the spacecraft and the star.
"Combining many of these occultations at different viewing geometries is like doing a CAT scan of the rings," said Colwell. "By studying the brightness of stars as the rings pass in front of them, we are able to map the ring structure in 3-D and learn more about the shape, spacing and orientation of clusters of particles."
The observations confirm that the gravitational attraction of ring particles to each other creates clumps, or "self-gravity wakes." If the clumps were farther from Saturn, they might continue to grow into a moon. But because these clumps are so close to Saturn, their different speeds around the planet counteract this gravitational attraction so that the clumps get stretched like taffy and pulled apart. The clumps are constantly forming and coming apart once they reach about 30 to 50 meters (about 100 to 160 feet) across.
"At any given time, most particles are going to be in one of the clumps, but the particles keep moving from clump to clump as clumps are destroyed and new ones are formed," added Colwell.
In the dense B ring, the classical cloud model of the rings predicted that particles collide about twice per hour on average. "Our results show that the particles in the B ring spend most of their time in almost continuous contact with other particles," said Colwell. These clumps may act like super-sized particles, changing the way the rings spread due to collisions.
The clumps are seen in all regions of the B ring that are not opaque. One surprising aspect of the measurements is that the clumps in the B ring are broad and very flat, like big sheets of particles. They are roughly 10 to 50 times wider than they are thick. Scientists are also surprised that the B ring clumps are flatter and have smaller spaces between them than those found in the neighboring A ring.
[ 本帖最后由 meteorobs 于 2007-5-25 19:07 编辑 ] 还没看英文，先问个问题，是真色？ 正文里貌似也没说。。。 用户: lackar 在文中写到:
不好看。
泼你冷水了
其实图还是蛮漂亮的，呵呵
好久不见楼主来本版，鼓掌欢迎！
但是得给老朋友提个意见：标下来源，OK?
另外，本帖再次诚征翻译
鉴于文字太长，奖励66牧夫币！
[ 本帖最后由 Eldghost 于 2007-5-23 22:57 编辑 ] 多谢斑竹提醒，已经更正过了。。::0020:: Cassini 'Cat Scan' Maps Clumps in Saturn's Rings卡西尼获得土星光环的“造影扫描”图集
http://jpl.nasa.gov/images/cassini/2007-05-22/pia09210-browse.jpg
This false-color image of Saturn's mainrings was made by combining data from multiple star occultations usingthe Cassini ultraviolet imaging spectrograph.
Image credit:NASA/JPL/University of Colorado
这张土星主光环伪彩图是用卡西尼的紫外成像摄谱仪获得的图片拼合的。图像使用了多重星光遮蔽系统（我猜测是把土星、卫星的所有光、像如同日冕仪那样遮蔽了）。 之所以说是主光环，看这张图，显然最外面的和最里面的环都没包括，但光环的主要部分都在这张图上了。
http://photojournal.jpl.nasa.gov/figures/PIA09210_fig1.jpg 本帖最后由 gohomeman1 于 2009-4-28 12:15 编辑
May 22, 2007
Saturn's largest and most densely packed ring is composed of tightly packed clumps of particles separated by nearly empty gaps, according to new findings from NASA's Cassini spacecraft.
根据卡西尼飞船的最新观察资料，土星最大和大部分相对密实的光环由致密的物质小团块组成，光环之间、团块之间由空隙分开。（看图就明白了，像唱片一样的环，环之间是空隙，而环本身也是石块团啊——译注）
These clumps in Saturn's B ring are neatly organized and constantly colliding, which surprised scientists.
科学家感到惊讶，B环内的团块虽然持续的在碰撞着，但整体上B环仍旧整齐有序。
"The rings are different from the picture we had in our minds.We originally thought we would see a uniform cloud of particles.Instead we find that the particles are clumped together with empty spaces in between," said Larry Esposito, principal investigator for the Cassini ultraviolet imaging spectrograph at the University of Colorado, Boulder."If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth.This is different from flying under a uniform cloud of particles."
"光环的实际与我们想象的不同。我们本来预想会看见整齐的小粒子云（组成光环整体），但实际上我们发现小粒子团聚成块，中间则是空隙。"Boulder市科罗拉多大学的卡西尼紫外成像仪图像研究团队负责人Larry Esposito说，“如果你在光环下面飞行，就会看见阳光透过环的空隙照下来，等等，这与你在一整片乌云下面飞是不同的”。
PS：其实这些是理所当然的，貌似这些知识我20年前刚刚学习的时候就知道了。只是卡西尼把光环大大的精细化了，以前我们分不开这么多小细环是真的。
Boulder市貌似该翻译为布兰多市？反正不是小石城也没有叫圆石市的，此处附近有个大水库。 本帖最后由 gohomeman1 于 2009-4-28 12:07 编辑
Because previous interpretations assumed the ring particles were distributed uniformly, scientists underestimated the total mass of Saturn's rings. The mass may actually be two or more times previous estimates.
由于之前科学家假设环的质量分布是均匀的，科学家低估了光环的质量。实际质量可能2倍或更多倍于以前的预估值。
"These results will help us understand the overall question of the age and hence the origin of Saturn's rings," said Josh Colwell, assistant professor of physics at the University of Central Florida, Orlando, and a team member of the Cassini ultraviolet imaging spectrograph. A paper with these results appears in the journal Icarus.
奥兰多市中弗罗里达大学的天体物理学家、卡西尼紫外图像研究团队成员 Josh Colwell说：“这些研究结果有助于我们了解光环的年龄、起源等所有问题”。相关的一份报告已经发表在 Icarus杂志上。
Scientists observed the brightness of a star as the rings passed in front of the star on multiple occasions. This provided a measurement of the amount of ring material between the spacecraft and the star.
科学家观察了光环掩星时星光亮度的多次变化。这提供了一个测量卡西尼飞船与恒星之间光环物质数量的（方法、机会）。
PS：Icarus国内一般翻译为国际太阳系研究杂志 经过组合的色彩很有层次感。不过我想看下真色。 本帖最后由 gohomeman1 于 2009-4-28 12:18 编辑
"Combining many of these occultations at different viewing geometries is like doing a CAT scan of the rings," said Colwell. "By studying the brightness of stars as the rings pass in front of them, we are able to map the ring structure in 3-D and learn more about the shape, spacing and orientation of clusters of particles."
“从不同的角度观察这些掩星现象就像给光环做一个CAT扫描”，Colwell说。“通过研究光环在恒星前通过时星光的变化，我们能够获得更多的光环中物质团块的形状、方位、空隙等信息，从而构造光环的3D结构”。（所以说标题是造影扫描——译注）
The observations confirm that the gravitational attraction of ring particles to each other creates clumps, or "self-gravity wakes."If the clumps were farther from Saturn, they might continue to grow into a moon. But because these clumps are so close to Saturn, their different speeds around the planet counteract this gravitational attraction so that the clumps get stretched like taffy and pulled apart. The clumps are constantly forming and coming apart once they reach about 30 to 50 meters (about 100 to 160 feet) across.
观察确认了光环内粒子间的万有引力使它们团聚成块，或者叫“自引力效应”。如果这些团块能离土星更远的话，它们将互相合并为（较大的）卫星。但由于它们离土星太近了，为了抵消行星的引力，各部分需要不同的运动速度，结果它们被土星强大的引力像拉牛奶糖一样的拉开。物质团块不断的形成，而一旦它们达到30—50米直径就会被起潮力拉开。
"At any given time, most particles are going to be in one of the clumps, but the particles keep moving from clump to clump as clumps are destroyed and new ones are formed," added Colwell.
Colwell补充说："在任何时间，小粒子不断的汇聚成团块，但大团块不断被土星引力破坏，粒子们就不断的在各个（中型）团块间转移"。
PS：这里我要说明一下，洛希极限不能简单的1、2句话就说清的，事实上光环内是有小卫星存在的。请大家自己搜索一下洛希极限的知识文章，有助于理解本段。——gohomeman1 本帖最后由 gohomeman1 于 2009-3-16 01:24 编辑
经过组合的色彩很有层次感。不过我想看下真色。
vivian260573235 发表于 2009-3-16 00:43 http://bootes.lamost.org/bbs/images/common/back.gif
本帖不是要你看真颜色的，你等我翻译完了就知道文章是什么意思了。这篇文章有助于深入了解土星光环。我可以很快的意译一下，不过这样人家对照英文看时就会说我根本是乱写。所以还是仔细的写比较好，希望大家既能比较明白，又不会说我是来骗悬赏分的（我想我够格拿分了）。
土星光环其实是小石块、冰块等组成的。 本帖最后由 gohomeman1 于 2009-4-28 12:08 编辑
In the dense B ring, the classical cloud model of the rings predicted that particles collide about twice per hour on average."Our results show that the particles in the B ring spend most of their time in almost continuous contact with other particles," said Colwell. These clumps may act like super-sized particles, changing the way the rings spread due to collisions. "
在稠密的B环，古典粒子云模型预计粒子碰撞频率是平均每小时2次。"我们的观察结果显示B环内的粒子在它们的大部分时间都在发生相互碰撞"，Colwell说。团块的举止很可能像超大粒子，通过碰撞改变运动方向并（最终）扩展为光环整体。（就是说碎片布满整个轨道区域——译注）
The clumps are seen in all regions of the B ring that are not opaque. One surprising aspect of the measurements is that the clumps in the B ring are broad and very flat, like big sheets of particles. They are roughly 10 to 50 times wider than they are thick.Scientists are also surprised that the B ring clumps are flatter and have smaller spaces between them than those found in the neighboring A ring.
团块看上去布满整个不透明的B环区域。一个令人惊讶的发现是B环又宽又平，它的宽度是厚度的10—50倍。科学家又惊讶的发现相对于临近的A环，B环的团块间间隙小而团块本身却更平整。
PS：我有点不懂，如果持续发生碰撞，那么粒子的动能不是会损耗吗？最后光环为什么没有落到土星大气内去？
原文主要内容翻译完毕。 本帖最后由 gohomeman1 于 2009-4-28 12:11 编辑
这是最后的说明段。
A picture of the rings based on these results is available at: http://www.nasa.gov/cassini, http://saturn.jpl.nasa.gov and http://lasp.colorado.edu/cassini/whats_new/ .
文章、图片还可以从上面的那些链接了解更多内容（比如我发的那张图）
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington.The Cassini orbiter was designed, developed and assembled at JPL.The ultraviolet imaging spectrograph was built at, and the team is based at the University of Colorado, Boulder.
卡西尼——惠更斯计划是美国、欧洲、意大利三家航天机构的合作计划。位于帕萨迪纳市加州理工学院分部的喷气推进实验室（简称JPL）具体实施卡西尼任务，向华盛顿的NASA理事会负责卡西尼飞船是在JPL设计并组装的。紫外图像成像仪由Boulder市科罗拉多大学制造并研究（拍摄成果）。
PS：英语就是喜欢长句，看得人头晕，听就更晕！ 本帖最后由 gohomeman1 于 2009-4-28 12:19 编辑
洛希极限的参考文章
http://zh.wikipedia.org/wiki/%E6%B4%9B%E5%B8%8C%E6%A5%B5%E9%99%90
http://baike.baidu.com/view/36843.htm 11# gohomeman1
改改错别字吧~~~
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