Copyright:Marcella Giulia Pace
Text:
Cecilia Chirenti
(NASA
GSFC,
UMCP,
CRESST II)
中文翻譯:
在西邊，太陽已經落下了，可是在東邊的天空卻出現了神奇的反夕光線！這幅圖畫展示了位於意大利西西里南部海布拉山脈的石灰岩高原，天空中出現了看似聚在東邊的反夕光線。那麼，反夕光線是怎麼出現的呢？其實，當太陽在西邊落下後，它的光線仍然照亮了天空中高高的雲彩。雲彩擋住了陽光，導致光和陰影的影子在天空中形成了平行的光線。因為透視的效果，這些光線看上去好像在東邊聚集，就像火車軌道在遠處的視覺效果一樣。這種現象在其他時候的日出時也會發生，但方向正好顛倒。在非常少見的情況下，夕光線和反夕光線還可以同時出現！
原文:
The Sun has just set… in the opposite side of the sky. Pictured here are anticrepuscular rays apparently converging in the east in this image of the limestone plateau in the heart of the Hyblaean Mountains of southeastern Sicily, in Italy. How were these anticrepuscular rays formed, if the Sun wasn’t there? After the Sun set (in the west, as usual) its light still illuminated a cloud higher up in the sky. Partially blocked by the cloud, the sunlight produced patterns of light and shadow, crossing the sky in parallel lines. Perspective makes it look like they converge in the east, in the same way that train tracks appear to meet in the distance. This effect can also happen at sunrise, only the directions are exchanged. In rare cases, both crepuscular and anticrepuscular rays can be seen at the same time.
來源:NASA每日圖片