[LAMOST科普]土星专辑:“卡西尼—惠更斯”土星探测器探索土星

还是

Hyperion (英语发音"hi PEER ee en")是土星已知卫星中距土星第十六近的一颗：

公转轨道: 距土星 1,481,100 千米
卫星直径: 286 千米 (410 x 260 x 220)
质量: 1.77e19 千克

   在希腊神话中，Hyperion是一个巨人，该亚与乌拉诺斯的儿子，Helios的父亲。

   它由波德和Lassell于1848年发现。

   土卫七是太阳系中最大的一颗高度不规则（非球形）天体。海卫八稍大一些，但差不多是个球体。看起来土卫七像是一颗大星体的碎片，大星体因在远古时期的碰撞而碎裂。

   就像土星的其他卫星，土卫七的低密度表明它由少量的岩石混合着冰水组成。

   不像土星的其他卫星的是，土卫七的反照率较小(.2 - .3)，表明它至少覆盖着一层薄薄的暗色物质。这可能是来自远于土卫八的更暗的土卫九上的物质。

   旅行者号带来的图片与基于地的光度测定表明土卫七的自转混乱，比如它的自转轴不停摇晃，在空间的方向无法确定。土卫七是太阳系已知星体中唯一一颗自转混乱的星体，不过其他星体可能在远古时期也这样。土卫七在其他不规则外形的星体中是独一无二的，公转偏心率较大，与另一颗大卫星土卫六很近。这些因素集合在一起，限制了它稳定自转的条件。土卫六与七的公转共振比为3:4，使它自转混乱更有可能。

   土卫七的奇怪自转可能起因于外形的不规则，与那些具有明显正半球与后半球的土星卫星形成对比。

Target Name: Saturn
Is a satellite of: Sol (our sun)
Mission: Cassini

Spacecraft: Cassini Orbiter

Instrument: Imaging Science Subsystem - Narrow Angle

Product Size: 1024 samples x 1024 lines
Produced By: CICLOPS/Space Science Institute

Primary Data Set: Cassini
Original Caption Released with Image:
This dramatic view of Saturn's rings draped by the shadow of Saturn, shows brightness variations that correspond to differences in the concentration of the ring particles as they orbit the planet.

The planet's western limb is visible in the upper right corner. Three of Saturn's moons can be seen here: Bright Enceladus (499 kilometers, or 310 miles across) is visible near lower right; Epimetheus (116 kilometers, or 72 miles across) appears at center left; and interior to the F ring, near the top of the image, is Prometheus (102 kilometers, or 63 miles across). The F ring, the outermost ring shown here, displays several knot-like features near the left side of the image.

The image was taken in visible light by the Cassini spacecraft wide angle camera on July 3, 2004, from a distance of 1.5 million kilometers (930,000 miles) from Saturn, at a Sun-Saturn-spacecraft, or phase, angle of about 108 degrees. This is the first processed wide angle camera image to be released since Cassini's encounter with Jupiter in 2000. The image scale is 87 kilometers (54 miles) per pixel.

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 Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.



Image Credit:
NASA/JPL/Space Science Institute

Target Name: Iapetus
Is a satellite of: Saturn
Mission: Cassini

Spacecraft: Cassini Orbiter

Instrument: Imaging Science Subsystem - Narrow Angle

Product Size: 442 samples x 442 lines
Produced By: CICLOPS/Space Science Institute

Primary Data Set: Cassini
Original Caption Released with Image:
The moon with the split personality, Iapetus, presents a puzzling appearance. One hemisphere of the moon is very dark, while the other is very bright. Whether the moon is being coated by foreign material or being resurfaced by material from within is not yet known.

Iapetus' diameter is about one third that of our own moon at 1,436 kilometers (892 miles). The latest image was taken in visible light with the Cassini spacecraft narrow angle camera on July 3, 2004, from a distance of 3 million kilometers (1.8 million miles) from Iapetus (pronounced eye-APP-eh-tuss).

The brightness variations in this image are not due to shadowing, they are real. The face of Iapetus visible was observed at a Sun-Iapetus-spacecraft, or phase, angle of about 10 degrees. The image scale is 18 kilometers (11 miles) per pixel. The image was magnified by a factor of two to aid visibility.

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 Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.



Image Credit:
NASA/JPL/Space Science Institute

Target Name: Saturn
Is a satellite of: Sol (our sun)
Mission: Cassini

Spacecraft: Cassini Orbiter

Instrument: Imaging Science Subsystem - Narrow Angle

Product Size: 850 samples x 702 lines
Produced By: CICLOPS/Space Science Institute

Primary Data Set: Cassini
Original Caption Released with Image:
Saturn's captivating cloud bands display a number of interesting features in this narrow angle camera image taken by the Cassini spacecraft on May 20, 2004. On close inspection, the sub-equatorial bands at around 20 degrees south latitude have a braided rope-like appearance. Also noteworthy are swirls and vortices around 60 degrees south latitude. The moon Mimas (398 kilometers, or 247 miles across) is visible just below and to the right of Saturn's South Pole.

The image was taken when Cassini was 22 million kilometers (13.7 million miles) from Saturn through a filter centered at 727 nanometers. The image scale is 131 kilometers (81 miles) per pixel. Contrast in the image was enhanced to aid visibility.

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 Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.



Image Credit:
NASA/JPL/Space Science Institute

Target Name: Saturn
Is a satellite of: Sol (our sun)
Mission: Cassini

Spacecraft: Cassini Orbiter

Instrument: Imaging Science Subsystem - Narrow Angle

Product Size: 764 samples x 656 lines
Produced By: CICLOPS/Space Science Institute

Primary Data Set: Cassini
Original Caption Released with Image:
Cassini captured intriguing cloud structures on Saturn as it neared its rendezvous with the gas giant. Notable is the irregularity in the eastern edge of the dark southern polar collar. The image was taken with the Cassini spacecraft narrow angle camera on May 21, 2004, from a distance of 22 million kilometers (13.7 million miles) from Saturn through a filter sensitive to absorption and scattering of sunlight in the near infrared by methane gas (centered at 727 nanometers). The image scale is 131 kilometers (81 miles) per pixel. No contrast enhancement has been performed on this image.

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 Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.



Image Credit:
NASA/JPL/Space Science Institute

Atmospheric Detail in Infrared
Target Name: Saturn
Is a satellite of: Sol (our sun)
Mission: Cassini

Spacecraft: Cassini Orbiter

Instrument: Imaging Science Subsystem - Narrow Angle

Product Size: 748 samples x 304 lines
Produced By: CICLOPS/Space Science Institute

Primary Data Set: Cassini
Original Caption Released with Image:
Details observed in Saturn's south polar region demonstrate that this area is far from featureless. Lighter colored clouds dot the entire region, which is dominated by a central, sharply-defined circular feature. Movie sequences in which these features are captured and followed will allow wind speeds in the polar region to be measured.

This image was taken with the Cassini spacecraft's narrow angle camera on May 20, 2004, from a distance of 22 million kilometers (13.7 million miles) from Saturn through a filter centered at 750 nanometers. The image scale is 131 kilometers (81 miles) per pixel. Contrast in the image was enhanced and magnified to aid visibility.

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 Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.



Image Credit:
NASA/JPL/Space Science Institute

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