Sometimes something rather special occurs. I am quite lucky that I live quite rural and am often blessed with night skies full of stars, and as I returned home and got out of my car I took my usual gaze upwards to see quite an amazing sight. It was the eve of a full moon and it was shining bright, only this time it was accompanied by its very own halo. It’s a rather cool phenomenon that only occurs when there are high clouds full of ice-crystals which refract the moon’s light at precisely 22 degrees. It is very similar to how rainbows occur with the sun. In fact some people call this a full 360 degree rainbow when it happens with the sun, so this is why I like to think of this as a ‘nighttime rainbow’. They are also referred to as “Moon Rings” or a “Winter Halo”. As sad as I am, I couldn’t help my excitement and dragged my children away from their Minecraft to come witness this amazing event – thankfully they equally found it as cool as I did – phew, my cool Dad status remains intact, for now.
Anyway, I thought it was worth a share on the blog for people to see and if you enjoyed it then please share or tweet using the ‘share’ button at the top of this post. Oh, and if you want to know a little more, here comes the geeky part and of course a diagram to help 🙂
This phenomenon actually occurs because there are millions of randomly angled hexagonal ice-crystals held high up in the sky by thin clouds. The moonlight passes through these prisms and are refracted twice (once as it enters, and again when it leaves), leaving at a 22 degree angle compared to it’s original path. The strange part is that very little light is refracted at a smaller angle, hence we see a darker area within the circle.
These night rainbows as you would expect bring some mystical meanings, and some believe them to be warnings to an incoming storm. In fact, some believe the number of stars within the halo predict how many days away the storm is… so hold on to your hats in about 4 days time 😉
Talking of stars, for those of you who are interested, getting really nerdy now, the brightest star in the bottom left is not actually a star it’s Jupiter. The bright star in the bottom right is Sirius, and above that you can make out the top half of Orion. When the moon is this bright it’s very hard to spot stars in the sky, and only the brighter ones shine through, but you can just make out part of Gemini at the top of the circle.