満月となった12月16日から18日にかけて、月を大きく囲む輪のようになる現象「月暈（げつうん）」が各地で観測された。月暈とは、月の周囲に現れる輪状の光暈のこと。月の光が細かい氷の結晶からできている雲に反射・屈折して起こるという。
早速、撮られた美しい「月暈」の写真を見てみよう。
【星空の画像集】
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アイソン彗星画像集
Comet ISON as seen by STEREO on Nov. 25, 2013(01 of04)
一時、核が崩壊したのではないかと心配されたアイソン彗星だが、その後無事姿が確認された\n\nA screen capture from the latest movie from the STEREO-A spacecraft\'s Heliospheric Imager shows the comet on Nov. 25, 2013. (credit:NASA)
Comet ISON Streaks Toward the Sun(02 of04)
Comet ISON shows off its tail in this three-minute exposure taken on Nov. 19, 2013 at 6:10 a.m. EST, using a 14-inch telescope located at the Marshall Space Flight Center. The comet is just nine days away from its close encounter with the sun; hopefully it will survive to put on a nice show during the first week of December. The star images are trailed because the telescope is tracking on the comet, which is now exhibiting obvious motion with respect to the background stars over a period of minutes.\nAt the time of this image, Comet ISON was some 44 million miles from the sun -- and 80 million miles from Earth -- moving at a speed of 136,700 miles per hour. (credit:NASA/MSFC/Aaron Kingery)
Bright Comet ISON(03 of04)
Comet ISON shines brightly in this image taken on the morning of Nov. 19, 2013. This is a 10-second exposure taken with the Marshall Space Flight Center 20\" telescope in New Mexico. The camera there is black and white, but the smaller field of view allows for a better \"zoom in\" on the comet\'s coma, which is essentially the head of the comet. (credit:NASA/MSFC/MEO/Cameron McCarty)
Comet Ison Roars Through Leo(04 of04)
In the early morning of Oct. 25 (6:45 a.m. EDT), NASA\'s Marshall Space Flight Center in Huntsville, Ala., used a 14\" telescope to capture this image of Comet C/2012 S1 (ISON), which is brightening as it approaches the sun. The comet shines with a faint green color just to the left of center. The diagonal streak right of center was caused by the Italian SkyMed-2 satellite passing though the field of view. At magnitude 8.5, the comet is still too faint for the unaided eye or small binoculars, but it\'s an easy target in a small telescope.\nAt this time of this image, ISON was located in the constellation of Leo the Lion, some 132 million miles from Earth and heading in toward the sun at 87,900 miles per hour. (credit:NASA/MSFC/Aaron Kingery)