Friday Morning's Lunar Event Only Comes Around Once in a Blue Moon

Last Updated by Michael Zimny on

Friday morning sky gazers will get a chance that only comes around once in a blue moon. Twelve full moons is good enough for most years, but some years are special. Those years, like 2015, get 13. That bonus moon is referred to as a blue moon. And that's what will appear in the sky early the morning of July 31.

Technically, there are two variations on the blue moon, says Thomas Durkin, Deputy Director of the South Dakota Space Grant Consortium

“The current accepted definition of a blue moon is the second full moon in a single calendar month, which is what we have coming up tomorrow. The second definition is the third full moon in a given season that has four moons," says Durkin.

The last blue moon to fit definition number two occurred on August 20, 2013.

The term blue moon does not refer to color, but don't give up on seeing a truly blue moon just yet.

“When the moon changes color, it can usually be either a reddish color due to dust and particles in the atmosphere, or if the particles in the atmosphere are the right size, it can actually appear blue or lavender" says Durkin. "That occurs less frequently than red moons, otherwise known as blood moons. 

“But it can happen, and it has happened in the past, where the moon does appear blue. There were several volcanic eruptions. There was a real significant one back in 1883 with [the eruption of] Krakatoa, where the moon appeared very blue. It also occurred with the eruption in 1980 of Mount St. Helens, and in 1991 of Mount Pinatubo.

pinatubo.jpgParticles from the 1991 eruption of Mount Pinatubo in the Philippines caused the appearance of a blue moon.

“What has to happen is the right sized particles have to be released into the atmosphere. They have to be about one micrometer in diameter. And if that is the only size of particles in the atmosphere, it filters out the red light in the visible spectrum, and scatters that red light, and the moon then appears a bluish color.

"The blue moon will probably not appear blue, because there aren’t any forest fires sending particles up. At least it won’t appear blue in South Dakota.”

Though the moon will appear full to the naked eye on through Thursday night and into early Friday morning, viewers who wish to truly commune with the blue moon will need to set their alarms.

"The full moon only occurs for about a second," says Durkin, "when the moon is exactly opposite the sun in the earth’s orbit. The actual time for the blue moon will occur at 4:43am Rapid City time."

Visibility should be pretty accessible to all, but for optimum viewing, consider an unobstructed view to the West. “At 4:43am (MT) the moon will be getting close to setting, so you’ll want a good view to the West. You won’t want to be in a valley, where you’ve got a high hill blocking out your view to the western horizon." 

food blog link image children and education blog image arts & culture blog news and information blog link sports blog link image
subscribe to sdpb email updates

The Latest From SDPB Radio News

IHS Deal To Save SD Millions Not An Option

Governor Dennis Daugaard says South Dakotans should not expect millions of dollars from IHS. A deal with the Indian...

Initiated Measure 22—A Main Focus Of Daugaard’s Budget Address

Governor Dennis Daugaard does not mince his words in his opposition to the voter approved Initiated Measure twenty...

Republicans Attain Statehouse Supermajority

Republicans have a super-majority in both chambers of the South Dakota state legislature. State Representative...

Governor Dennis Daugaard’s FY18 Budget Address

Governor Dennis Daugaard is proposing a total budget of $4.6-billion for fiscal year 2018. The state is seeing lower...

Dakota Midday: A Poem A Day

By December, most New Year's resolutions are long forgotten. Poet Jay Sanchez, however, is still going strong...

Dakota Midday: 2016 Holiday Jam Tour

Jon and Jeremy Hegg make their annual visit to Dakota Midday in the midst of this year's Holiday Jam with the Hegg...

Lakota Community Unites To Fight Child Abuse

The discovery of two severely malnourished and abused girls on the Pine Ridge Reservation has resulted in concern...

AG's Opinion Clarifies Amendment S Effect On Crime And Accident Information

The South Dakota Attorney General has issued an opinion that Amendment S, or Marsy's Law, does not prevent the...

Attorney General Drafts Opinion To Answer Marsy's Law Questions & Concerns

The Attorney General is issuing a 10-page opinion to clear up some questions created by Amendment S, or Marsy's Law....

Dakota Midday: A Lifechanging Day For Dr. Holm

Dr. Rick Holm is a physician, a husband, a father and a singer. He has been the host of On Call with the Prairie Doc...

The Latest from NPR News

'Frantic' Search For Survivors After Earthquake In Indonesia Kills Nearly 100

A magnitude-6.5 quake off the coast of the Aceh province has destroyed hundreds of buildings. Authorities say there...

Democrats Make Long-Shot Effort To Win Louisiana Senate Seat

Following Donald Trump's victory, Democrats around the country have suddenly focused on Foster Campbell's campaign...

Reporter's Notebook: What It Was Like For A Muslim To Cover The Election

NPR's Asma Khalid reflects on a year covering politics at a moment when being Muslim was seen as a political problem...

As Syrian Government Forces Advance, The War Could Be At A Turning Point

After more than five years of fighting, President Bashar Assad's military is making significant advances against...

Trump Touts Military Strength In N.C. On Second Stop Of 'Thank You' Tour

The president-elect also formally introduced retired Marine Corps Gen. James Mattis as his pick to lead the Defense...

Pipeline Protesters, Battered By Blizzard, Vow To Stay

Amid their recent victory, people protesting the Dakota Access Pipeline are huddling in shelters in North Dakota as...