夏至

2020 June 20 Northern Summer on Titan Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA Explanation: Today’s solstice brings summer to planet Earth’s northern hemisphere. But the northern summer solstice arrived for ringed planet Saturn over three years ago on May 24, 2017. Orbiting the gas giant, Saturn’s moon Titan experiences the Saturnian seasons. Larger than inner planet Mercury, Titan was captured in this Cassini spacecraft image about two weeks after its northern summer began. The near-infrared view finds bright methane clouds drifting through Titan’s dense, hazy atmosphere as seen from a distance of about 507,000 kilometers. Below the clouds, dark hydrocarbon lakes sprawl near its fully illuminated north pole. Tomorrow’s picture: Venus by moonlight 土卫六北半球的夏天 影像提供：Cassini Imaging Team, SSI, JPL, ESA, NASA 说明：明天的夏至将把夏天带到地球北半球，但对拥有行星环的土星而言，北半球的夏至降临在3年前的5月24日。而在绕行这颗气态巨行星的土卫六，也感受到土星的季节变化。这张呈现大于水星的土卫六的影像，是由卡西尼号太空船摄于土星夏季降临的2星期多之后。这张摄于约507，000公里之外的近红外光照片，记录了漂过土卫六致密雾霾天空的明亮甲烷云。在云层下方，可见到在阳光照耀的土卫六北极区，以及它附近广袤的暗色碳氢化合物湖泊。…

2019 December 22 Solstice Illuminated: A Year of Sky Video Credit & Copyright: Ken Murphy (MurphLab); Music: Ariel (Moby) Explanation: Can you find which day is the winter solstice? Each panel shows one day. With 360 movie panels, the sky over (almost) an entire year is shown in time lapse format as recorded by a video camera on the roof of the Exploratorium museum in San Francisco, California. The camera recorded an image every 10 seconds from before sunrise to after sunset and from mid-2009 to mid-2010. A time stamp showing the local time of day is provided on the lower right. The videos are arranged chronologically, with July 28 shown on the upper left, and January 1 located about half way down. In the…

2019 September 28 An Analemma of the Sun Image Credit & Copyright: Gyorgy Soponyai Explanation: This week the equinox found the Sun near the middle, but not at the crossing point, of an analemma in its annual trek through planet Earth’s skies. In this scenic view, that graceful, figure-8-shaped curve was intentionally posed above the iconic Danube River and the capital city of Hungary. Looking south from Budapest’s Margaret Bridge it combines digital frames taken at exactly the same time of day (11:44 CET) on dates between 2018 September 24 and 2019 September 15. That puts the metropolitan Pest on the left, regal Buda on the right, and the positions of the Sun on the solstice dates at the top and bottom of the analemma…

2019 June 28 巴黎的夏至夜 影像来源及版权: Michel Loic 说明：6月21日的夜晚是地球北纬地区时长最短的夜晚，因此位于北纬48.9度的巴黎也不例外。尽管如此，这座光明之城仍然异常明亮。在夏至日落后，天空中布满了银色的夜光云。流星尘或火山灰上的冰冷凝结物悬浮在太空边缘，它们位于中气层最大高度、强烈的阳光下。在夏季的高纬度地区，我们可以看到引人注目且广泛分布的北方夜光云。 A Solstice Night in Paris Image Credit & Copyright: Loic Michel Explanation: The night of June 21 was the shortest night for planet Earth’s northern latitudes, so at latitude 48.9 degrees north, Paris was no exception. Still, the City of Light had an exceptionally luminous evening. Its skies were flooded with silvery night shining or noctilucent clouds after the solstice sunset. Hovering at the edge of space, the icy condensations on meteoric dust or volcanic ash are still in full sunlight at the extreme altitudes of the mesophere. Seen at high latitudes in summer months, stunning, wide spread displays of northern noctilucent clouds are now being reported.

2019 June 27 时长越来越长的白昼 影像来源及版权: Gianluca Belgrado 说明：这幅持续拍摄六个月的长曝光影像将从冬至到夏至（2018年12月21日至2019年6月16日）的时间压缩成一个单一的视角。这幅不寻常的影像被称为日轨图，它是由一台高大的管状针孔相机、通过使用一张照相纸拍摄而成。这台简易的相机被固定在意大利.卡萨拉诺的一个单一地点上，并连续不断地记录太阳的日常路径，就像一道炽热的轨迹在感光纸上燃烧一样。这些轨迹上的中断和缺口是由云层造成的。在曝光结束时，我们对纸张进行扫描从而构建出这幅数字影像。当然，从12月开始，太阳轨迹会在临近北半球冬至时落在天空中的较低处。随着白昼时长的增加和6月21日夏至的来临，太阳轨迹会越升越高。 The Longer Days Image Credit & Copyright: Gianluca Belgrado Explanation: This persistent six month long exposure compresses the time from solstice to solstice (December 21, 2018 to June 16, 2019) into a single point of view. Dubbed a solargraph, the unconventional picture was recorded with a tall, tube-shaped pinhole camera using a piece of photographic paper. Fixed to a single spot at Casarano, Italy for the entire exposure, the simple camera continuously records the Sun’s daily path as a glowing trail burned into the photosensitive paper. Breaks and gaps in the trails are caused by cloud cover. At the end of the exposure, the paper was scanned to create the digital image. Of course, starting in December…

2019 June 21 落日时分的日行迹 影像来源及版权: Marcella Giulia Pace 说明：今天世界时间15点54分夏至来临之时，太阳在其每年穿过地球天空的旅程中会到达赤纬最北的位置。在天文学上，夏至标志着北半球夏季和南半球冬季的开始。今天也是北半球日出到日落之间白昼最长的一天。实际上，夏至的太阳位于这幅合成影像的顶部附近，也就是由太阳位置绘制的日行迹或8字曲线最北点。这道日行迹是由从2018年6月21日到2019年6月7日，每十天在同一时间拍摄的影像构建而成。拍摄时间被选择为一年中日落时间最早的冬至附近，因此日行迹的最低点正好与影像左侧一览无余的海平面相接。沿地平线向右（北）分布的落日以秋分的落日为中心，以夏至的落日结束点。 Sunset Analemma Image Credit & Copyright: Marcella Giulia Pace Explanation: Today, the solstice is at 15:54 Universal Time, the Sun reaching the northernmost declination in its yearly journey through planet Earth’s sky. A June solstice marks the astronomical beginning of summer in the northern hemisphere and winter in the south. It also brings the north’s longest day, the longest period between sunrise and sunset. In fact the June solstice sun is near the top, at the most northern point in the analemma or figure 8 curve traced by the position of the Sun in this composite photo. The analemma was created (video) from images taken every 10 days at the same time from June 21, 2018…