オリジナル記事:Sliver of Saturn

Although only a sliver of Saturn’s sunlit face is visible in this view, the mighty gas giant planet still dominates the view.

From this vantage point just beneath the ring plane, the dense B ring becomes dark and essentially opaque, letting almost no light pass through. But some light reflected by the planet passes through the less dense A ring, which appears above the B ring in this photo. The C ring, silhouetted just below the B ring, lets almost all of Saturn’s reflected light pass right through it, as if it were barely there at all. The F ring appears as a bright arc in this image, which is visible against both the backdrop of Saturn and the dark sky. (For a diagram showing the names and positions of the rings see Expanse of Ice .)
土星の環の平面の直下にあたるこの視点から、高密度のB環は暗くなり、実質的に不透明になり、光はほとんど通過しなくなります。しかし、土星によって反射された光の一部は、この画像のB環の上に現れ、より密度の低いA環を通過しています。 B環の真下にあるC環の影は、まるでまったく存在しないかのように、土星の反射光の殆どすべてをそのまま通過させています。 F環は、この画像に明るい弧として見えていて、土星の背景と暗い宇宙空間の両方から見ることができます。 (土星の環の名前と位置については「Expanse of Ice」の図を参照してください)。

This view looks toward the unilluminated side of the rings from about 7 degrees below the ring plane. The image was taken in green light with the Cassini spacecraft wide-angle camera on Jan. 18, 2017.

The view was acquired at a distance of approximately 630,000 miles (1 million kilometers) from Saturn. Image scale is 38 miles (61 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, ESA (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 mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit and . The Cassini imaging team homepage is at .

Credit: NASA/JPL-Caltech/Space Science Institute
Last Updated: April 4, 2017
Editor: Martin Perez


記事中にある土星の環の図(Expanse of Ice)とは以下の記事にあります。