Once in a ‘blue moon’: Seattle night sky will be bright this August

31 July 2023

Ever heard the term ‘once in a blue moon?’ This August will have two full moons, and the second one near the end of the month is called a ‘blue moon.’

The first full moon will be Tuesday night and is called the ‘sturgeon moon’. The sturgeon moon has that name as the first full moon of the month because the Sturgeon fish are most readily caught in the Great Lakes and Lake Champlain at that time, according to the Farmer’s Almanac. Others call the sturgeon moon the ‘corn moon’.

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The sturgeon moon will also be a supermoon. The moon’s orbit around Earth is an ellipse versus a full circle, meaning that there are times when the moon’s orbit gets closer to the planet. The sturgeon moon in August will be one of those closest moments, making the moon appear larger and brighter than other full moons.

The following full moon will occur late in the month, August 30 and 31, making it a blue moon.

There are two definitions of a blue moon. One is when a second full moon occurs in the same calendar month, and that is the case near the end of August. The other definition for a blue moon is that four full moons occur in a season, such as the summer season.

Going back in history, the term blue moon originated following the eruption of Krakatoa in 1883, putting so much volcanic dust in the atmosphere that the moon appeared blue in color.

The phrase, ‘once in a blue moon’, refers to a rare event. But in fact, astronomical blue moons occur more frequently, occurring on average about every 33 months, according to space experts. The last blue moon was in August 2021 and was the fourth full moon of that summer.

The full moon near the end of August will also be a supermoon. In fact, the full moon at the end of August will be the closest to Earth this year, meaning it will be the biggest and brightest of 2023.

The weather to view the sturgeon moon Tuesday night looks to be ideal, with clear skies in store. The way this summer has been going, the odds favor good viewing of the blue moon near the end of August as well.

Follow Ted Buehner, the KIRO FM news meteorologist on Twitter 

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