This common lunar phenomenon makes night sky watching pretty interesting.

The Final Full Moon of Summer

On Friday, September 9th, we saw the final full moon of summer. What was really cool about this year's final full moon of summer, was that it also happened to be the Harvest Moon. The Harvest Moon is the name for the full moon that arrives closest to the autumn equinox. Usually, the Harvest Moon occurs in September but occasionally it will occur as late as October.

In 2022, the Harvest Moon occurred in September which is not uncommon at all, but it happened before it's officially autumn. The Farmer's Almanac has a lot of really good information on the Harvest Moon, and why this year the Harvest Moon didn't fall during, well fall. When you looked up at the moon over the weekend, did you happen to see a ghostly ring around it? That's called a lunar halo, and they're pretty cool.

My friend Hilary snapped this incredible photo of the Harvest Moon over the weekend:

Ghostly Rings Around the Moon are Lunar Halos

I remember when I was a kid my dad told me that if you noticed a ring around the moon that meant it was going to rain. I figured it was just a cool old wives tale, but actually, he wasn't too far off. Rings around the moon aren't uncommon, and they're actually called lunar halos.

According to the Farmer's Almanac here is why lunar halos happen:

A lunar halo is caused by the refraction, reflection, and dispersion of light through ice particles suspended within thin, wispy, high altitude cirrus or cirrostratus clouds. As light passes through these hexagon-shaped ice crystals, it is bent at a 22-degree angle, creating a halo 22 degrees in radius (or 44 degrees in diameter).

The Farmer's Almanac goes on to share the common weather lore rhyme:

A ring around the sun or moon, means rain or snow is coming soon.

They say that's actually not too far off. Since the lunar halo is usually caused within cirrus and cirrostratus clouds this is often true as those types of clouds are typically seen before rain and storm systems.

So if you look up to the night sky and notice a lunar halo, you may want to keep your raincoat handy!