Look east for a blue moon Friday night

A second full moon known as the "blue moon" graces the night sky Friday

This Friday the moon will provide an astronomical treat for sky gazers. A second full moon of July will grace the night sky on Friday, known as a blue moon.

The celestial moment is actually a calendar quirk, when there is a full moon early enough in the month for another to appear at the end of the month. It takes 29-1/2 days for another full moon to occur. The first full moon happened on July 2 and Friday, July 31 will bring the blue moon.

The last time this happened was in 2012 and it may not happen again until 2018.

Will the moon really be blue? Probably not, but it has happened in the past. In 1883, an Indonesian volcano named Krakatoa erupted sending ash into the Earth’s atmosphere giving the moon a blue haze. As moonbeams passed though the ash particles the clouds appeared blue and sometimes green even, according to NASA.

Why call it a blue moon if it won’t be blue? It turns out the name comes from an error printed in Sky and Telescope magazine in 1946. They admitted their “blue moon blooper” in a detailed explanation here.

Even if it’s not really blue, the extra full moon provides a great opportunity for taking photos or a moonlit hike. Check with your local parks to see if they are offering an extra full moon guided tour this month. These Florida tour companies offer full moon paddles by kayak, canoe or paddleboard.

Happy sky gazing!


Feeling blue? Tweet me your blue moon photos and follow me @emspeck for more skygazing tips.

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