Weird Science

Moon Halo

Polish ver­sion is here

The lunar halo is one of the fasci­na­ting opti­cal phe­no­mena obse­rva­ble in the night sky. The sight of a lumi­nous ring encirc­ling the Moon's disk inspi­res awe and prompts reflec­tion on the beauty of our atmo­sphere. Since ancient times, peo­ple have taken note of this extra­or­di­nary phe­no­me­non, attri­bu­ting various mysti­cal mea­nings to it. It was also belie­ved that halos (both lunar and solar) fore­told wea­ther chan­ges, and in some cul­tu­res, they were inter­pre­ted as signs of divine pre­sence or impen­ding signi­fi­cant events.

In Euro­pean cul­tu­res, this phe­no­me­non was often con­si­de­red a har­bin­ger of storms, snow­falls, or other abrupt atmo­sphe­ric chan­ges. Simi­lar beliefs pre­va­i­led in Asia­—an­cient Chi­nese prie­sts and astro­lo­gers read opti­cal phe­no­mena in the sky as mes­sa­ges from gods and impe­rial ance­stors. Among indi­ge­nous peo­ples of the Ame­ri­cas, the halo sym­bo­li­zed balance and the cyc­li­cal nature of nature.

Today, thanks to scien­ti­fic rese­arch, we know that it is an opti­cal effect asso­cia­ted with the refrac­tion of light in ice cry­stals. Despite this scien­ti­fic expla­na­tion, its remar­ka­ble appe­a­rance con­ti­nues to evoke admi­ra­tion and inte­rest, serving as a remin­der of the beauty and mystery of the world aro­und us.

This phe­no­me­non occurs due to the refrac­tion of moon­li­ght in tiny ice cry­stals suspen­ded in the upper lay­ers of the atmo­sphere, typi­cally in cir­rus or cir­ro­stra­tus clo­uds. As light pas­ses thro­ugh these ice cry­stals, it is refrac­ted at an angle of 22°, lea­ding to the for­ma­tion of a cha­rac­te­ri­stic ring with that exact dia­me­ter aro­und the Moon. Simi­lar to solar halos, the inner edge of the ring is the bri­gh­test, and the sky within the halo appe­ars dar­ker than the sur­ro­un­ding sky.

Lunar halos appear in the pre­sence of high-alti­tude clo­uds, such as cir­ro­stra­tus or cir­rus, which con­tain ice cry­stals flo­a­ting at alti­tu­des of 5-10 kilo­me­ters.

Obse­rva­tions

Febru­ary 16, 2025, aro­und 3:14 AM - Jaworzno (Poland)
Con­di­tions: urban

It might seem that a sky cove­red with wispy clo­uds and fog han­ging in the air are con­di­tions in which we wouldn't expect any inte­re­sting astro­no­mi­cal or atmo­sphe­ric phe­no­mena. Howe­ver, it is pre­ci­sely under such cir­cum­stan­ces that lunar halos are most often visi­ble. Despite the chal­len­ging con­di­tions, I mana­ged to cap­ture it in Photo 1.

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Photo 1

In the pho­to­graph, a sub­tle ring encirc­ling the Moon's disk is visi­ble. The Moon appe­ars only as a white spot because, to cap­ture the faint halo, it was neces­sary to set a suf­fi­cien­tly long expo­sure time, resul­ting in the ove­re­xpo­sure of our natu­ral satel­lite's image.

Fur­ther rea­dings:

Marek Ples

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