2021年的天空
(原标题: The Sky in 2021)
2022-03-21
浏览次数: 17
如果你能在一整年的时间里看到整个天空会怎么样？这几乎就是这里所描绘的。在2021年，每隔15分钟，一台全天候摄像机就会拍摄一张荷兰的天空图像。然后将这些图像的中心列对齐并组合成特色的keogram， 1月在顶部，12月在底部，午夜在中心左侧垂直运行。我们看到了什么？最明显的是，白天的天空大部分是蓝色的，而夜晚的天空大部分是黑色的。穿过夜空的十二道光带是由月亮的光辉造成的。黑色沙漏形状的最薄部分出现在白昼最长的夏至，而最厚的部分出现在冬至。昨天是昼夜相等的春分，而一年前的北春分实际上可以定位在keogram（水壶）上——大约在上面四分之三的地方。在Instagram上关注APOD：英语、印尼语、波斯语、葡萄牙语或台湾语
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What if you could see the entire sky -- all at once -- for an entire year? That, very nearly, is what is pictured here. Every 15 minutes during 2021, an all-sky camera took an image of the sky over the Netherlands. Central columns from these images were then aligned and combined to create the featured keogram, with January at the top, December at the bottom, and the middle of the night running vertically just left of center. What do we see? Most obviously, the daytime sky is mostly blue, while the nighttime sky is mostly black. The twelve light bands crossing the night sky are caused by the glow of the Moon. The thinnest part of the black hourglass shape occurs during the summer solstice when days are the longest, while the thickest part occurs at the winter solstice. Yesterday was an equinox -- when night and day were equal -- and the northern-spring equinox from one year ago can actually be located in the keogram -- about three-quarters of the way up. Follow APOD on Instagram in: English, Indonesian, Persian, Portuguese or Taiwanese
© Cees Bassa (Netherlands Institute for Radio Astronomy)