토성의 폭풍

 

 

 

NASA의 카시니 호가 촬영한 이 사진은 토성 북반구에서 맹위를 떨치고 있는 거대 폭풍을 촬영한 것이다.

사진에 사용된 콘트라스트는 강조로 인해 주변 풍경에서 유실되는 부분이 전혀 없이, 가장 강력한 폭풍이 휘몰아치는 곳만을 하얀색으로 강조하여 표시하고 있다.

이 폭풍의 머리 부분은 사진 왼쪽에 밝은 구름들이 몰려 있는 부분이다.

시계방향으로 회전하고 있는 이 소용돌이 구름은 2010년 12월 초순 중위도에서 관측된 대기 상승현상 바로 이후에 생겨났다.
폭풍의 머리 부분은 매우 빠르게 서쪽으로 이동하고 있지만 소용돌이 자체는 이보다는 훨씬 느린 속도로 서쪽으로 움직이고 있다.

카시니호가 이 모자이크를 구성하고 있는 사진을 촬영한 것은 2011년 3월 6월이다.

사진의 중앙 부근은 경도 0도, 위도 35도 지역이다.

과학자들은 이 사진에 가시광선을 구성하는 색채로 빨간색과, 초록색, 파란색을 사용하였다.

그러나 이 사진은 실제 육안으로 봤을 때의 색깔이 아니다. 

콘트라스트를 강화시킨 이 사진에서 자연색의 비율은 일체 사용되지 않았다.

만약 이 광경을 육안으로 보게 된다면 색채 변이가 그다지 존재하지 않는 노란빛을 배경으로 그저 밝게 빛나는 점만을 보게 될 것이다.

그 모습은 PIA16724 를 참고하면 된다.
(참고 : http://photojournal.jpl.nasa.gov/catalog/PIA16724)

이 사진에서 밝기는 대상 구름이 위치하는 고도에 따라 달리 나타나고 있다.

하얀색으로 밝게 빛나는 부분은 대기권의 최상층에 있는 구름을 나타내고 어두운 부분은 구름이 첩첩이 쌓인 틈에 난 구멍을 나타낸다.

사진에서는 비록 색깔의 대비가 강조되어 표현되고 있지만, 원래 이 미묘한 색감의 차이는 아마도 각 구름들의 구성 성분의 차이에 기인하고 있는 것으로 보인다.
그러나 이러한 미묘한 색감의 차이를 만드는 원인은 여전히 미지의 영역으로 남아 있다.

출처 : NASA 제트추진연구소(JPL, Jet Propulsion Laboratory) Photo Journal

       http://photojournal.jpl.nasa.gov/catalog/PIA16720

 

참고 : 다양한 토성의 풍경 등, 토성과 토성의 여러 달에 대한 각종 포스팅은 아래 링크를 통해 조회할 수 있습니다. 
           https://big-crunch.tistory.com/12346948

 

원문>

This mosaic of images from NASA's Cassini spacecraft shows the trail of a great northern storm on Saturn raging in full force. The contrast in the images has been enhanced to make the turbulent parts of the storm (in white) stand out without losing the details of the surrounding regions.

The head of the storm is the set of bright clouds near the left of the image. A clockwise-spinning vortex spawned by the storm shortly after it erupted in early December 2010 can be seen in the middle. The head of the storm moved very swiftly westward, while the vortex drifted more slowly westward.

Cassini's imaging camera obtained the images that went into this mosaic on March 6, 2011. The image is centered at about 0 degrees longitude and 35 degrees latitude.

In this image, scientists assigned red, green and blue channels to those visible-light colors. However, this view is not what a human eye would see at Saturn -- in enhancing the contrast, the natural color balance was not preserved. To human eyes, storm would have appeared more like a bright feature against a yellow background with less color variation, as is seen in PIA16724. In this color scheme, the brightness generally corresponds to the altitude of the cloud features. Bright white indicates highest cloud tops in the troposphere, and dark places indicate holes in the cloud layer. The subtle colors that become apparent in this enhanced-contrast view are probably produced by variation in the composition of clouds. However, the coloring agents responsible for producing these subtle hues remain unidentified.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's 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, Colo.

For more information about the Cassini-Huygens mission, visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov/.

Image Credit: NASA/JPL-Caltech/SSI/Hampton University
Image Addition Date: 2013-01-31