The Gegenschein
影像版權與提供: Jimmy Westlake (Colorado Mountain College)
Explanation:
If you look carefully enough, you can even see the glow of the Sun in the opposite direction. At night this glow is known as the gegenschein (German for "counter glow"), and can be seen as a faint glow in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above, the gegenschein is seen superposed toward the constellation of Pisces. The gegenschein is distinguished from zodiacal light by the high angle of reflection. During the day, a phenomenon similar to the gegenschein called the glory can be seen in reflecting air or clouds opposite the Sun from an airplane.
說明:
如果你夠細心的話，你就能看到太陽的輝光在與太陽遙遙相對的另一邊的夜空中閃耀著。 這種夜空中的輝光，就是所謂的對日照( Gegenschein) (德文的意思即為"對面的輝光") ，只有在非常非常暗的夜空中，才能看到這種很暗的輝光。 對日照是日光經由塵埃粒子的反向散射所造成的。 這些大小只有幾毫米的 塵埃粒子是由小行星所分裂出來的碎片，並沿著黃道面運行。如上圖，對日照是出現在雙魚座之中。對日照與黃道光的不同是在於它的散射角度比較高 白天時，若是你在飛機中看到西邊的雲層受到來自東邊的陽光照射，使得雲層產生光暈， 那就是一種與對日照相類似的現象 。
資料來源: Scientific American
Department of Physics, NCKU
