Copyright:Damian Peach
原文:
On Saturn, the rings tell you the season. On Earth, today marks a solstice, the time when the Earth’s spin axis tilts directly toward the Sun. On Earth’s northern hemisphere, today is the Summer Solstice, the day of maximum daylight. Since Saturn’s grand rings orbit along the planet’s equator, these rings appear most prominent — from the direction of the Sun — when the Saturn’s spin axis points toward the Sun. Conversely, when Saturn’s spin axis points to the side, an equinox occurs and the edge-on rings are hard to see. In the featured montage, images of Saturn over the past 11 years have been superposed to show the giant planet passing from southern summer toward northern summer. Although Saturn will only reach its northern summer solstice in 2017 May, the image of Saturn most analogous to today’s Earth solstice is the bottommost one. Follow APOD on: Facebook, Google Plus, or Twitter
中文翻譯:
在土星，環帶讓你知道季節。在地球上，今天是至日，地球自轉軸直接傾向太陽的時候。在地球的北半球，今天是夏至，這是白天時間最長的一天。由於土星的壯觀環帶沿著行星的赤道運行，當土星的自轉軸指向太陽時，這些環帶看起來最為顯著。相反，當土星的自轉軸指向側面時，就會發生春分，環帶的邊緣變得難以看到。在這個精選的蒙太奇中，過去11年的土星圖像被疊加在一起，顯示這顆巨行星從南方夏季過渡到北方夏季。雖然土星要到2017年5月才會達到北方夏至，但最類似今天地球至日的土星圖像是最底部的那一張。
#土星環帶 #夏至 #壯觀景象 #天文學 #宇宙 #太陽系 #Astrophotography #SaturnRings #SummerSolstice #PlanetaryScience
來源:NASA每日圖片
