Great Moon Halo Display

Last updated on September 16, 2023

Great Moon Halo Display: A Spectacular Atmospheric Optics Phenomenon

On a cold winter night in Sotkamo, Finland, Marko Mikkilä witnessed one of the most remarkable lunar halo displays he had ever seen. Intrigued by the possibility of capturing the beauty of this natural phenomenon, Marko embarked on a special 6-700 km journey to the northern region, where ski-slope snow machines produce diamond dust crystals known for their exceptional optical quality. Little did he know that his efforts would be richly rewarded.

The captivating image that Marko captured reveals a dominant 22-degree halo, formed by randomly oriented ice crystals. But what makes this display truly extraordinary is the presence of a much rarer sight - a 46-degree halo, located just over twice the distance from the moon. This combination of halos creates a stunning visual spectacle in the night sky.

Touching the inner 22-degree halo at the top and bottom are circumscribed halos, resulting from horizontal column crystals. These crystals also give rise to other colorful phenomena, such as infralateral arcs and the paraselenic circle. Interestingly, the absence of moon dogs (paraselenae) suggests that there were few plate crystals present during this display.

In addition to the main image, Marko also captured an all-sky view and an unsharp masked version, which provide further insights into the atmospheric optics at play. These images reveal additional column arcs, Wegener arcs, and an exceptionally rare complete subhelic circle. It is worth noting that reproducing the complete subhelic circle in HaloSim ray tracing requires special crystals, suggesting the uniqueness of this particular event.

Further exploration of Marko's images from that evening unveils more captivating features. One image showcases a splendid lower tangent arc, which formed earlier in the evening. Additionally, there are traces of "flared" pillars above artificial lights, as clearly depicted in another image. These spatial halos, resulting from nearby horizontal columns, add another layer of complexity to the overall display.

To conclude the series of images, Marko presents a combination of lunar halos and those produced by a high-intensity lamp. This juxtaposition highlights the striking contrast between natural and artificial sources of light, offering a unique perspective on the interplay between atmospheric conditions and optics.

The Great Moon Halo Display captured by Marko Mikkilä serves as a testament to the mesmerizing beauty of atmospheric optics. It reminds us of the intricate processes occurring within our atmosphere, where ice crystals and light interact to create stunning visual phenomena. While these displays may be rare, they serve as a powerful reminder of the wonders that can unfold above us when we take the time to observe and appreciate the natural world around us. So, keep your eyes on the sky and be ready to witness the magic of atmospheric optics whenever it graces our nights.

Lunar Halos ~ Dec 3 Imaged by Marko Mikkil� at Sotkamo, Finland. Marko's website, halo images. �Marko Mikkil�, shown with permission.

Last Thursday night showed the best lunar halo displays that Marko Mikkil� had ever seen. Marko had made a special 6-700 km round trip up north to be in the vicinity of ski-slope snow machines because downwind of them can be found diamond dust crystals of superb optical quality. It was worthwhile!

The large image is dominated by a 22 degree halo from randomly oriented crystals. At just over twice the distance from the moon is a much less common sight, a 46� halo.

Touching the inner 22� halo at top and bottom is a circumscribed halo from horizontal column crystals. Columns also produced the colourful infralateral arcs and the paraselenic circle. That there are no moon dogs (paraselenae) tells us there were few plate crystals.

The all-sky view (2) and the unsharp masked version (3) show more column arcs, Wegener arcs and, very unusually, a complete subhelic circle (subselenic in this instance?). The HaloSim ray tracing identifies the arcs but does not reproduce the complete subhelic circle - special crystals are probably needed for that.

More of Marko�s images taken that evening (see the set) show column arcs. Image 4 has a splendid lower tangent arc produced earlier in the evening. There are also traces of 'flared' pillars above artificial lights. Image 5 shows the flares clearly. They are spatial halos, the result of nearby horizontal columns.

Finally (5) a combination of lunar halos and those from a high intensity lamp!

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