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." 

subscribe to sdpb email updates food and cooking banner image learning blog link living blog link news and information blog link science and technology blog link sports blog link image

The Latest From SDPB Radio News

Pine Ridge Based Food Truck Serving Traditional Taste

A new food truck on Pine Ridge is serving up traditional food. The business offers a taste of the reservation to...

'Voter Fatigue' Over 'Beach Towl Ballot' Is Main Focus Of Summer Task Force

After a laundry list of ballot measure questions during the last election, a legislative summer study commission is...

Congresswoman Noem Says Tax Overhaul Vote May Come Within Weeks

South Dakota’s lone US House Representative says the Ways and Means committee plans to release its blueprint of...

Innovation: Biotechnology Businesses, Biodegradable Plastics, Dr. K.

Biotechnology is a booming business, and South Dakota companies are competing with organizations around the globe...

In The Moment ... Moment In Sound With Richard Grewar

In The Moment ... June 23, 2017 Show 121 Hour 1 From England to Australia to Hill City, South Dakota, Richard Grewar...

SD Senators Support New GOP Health Care Overhaul

South Dakota’s United States Senators say their health care plan is better than the Affordable Care Act. Thursday...

In The Moment ... Congresswoman Kristi Noem

In The Moment ... June 22, 2017 Show 120 Hour 2 As Congressional Republicans push forward what Vice President Mike...

In The Moment ... Adoption And SB 149

In The Moment ... June 22, 2017 Show 120 Hour 1 Adam Pertman is President and CEO of the National Center on Adoption...

In The Moment ... Dakota Political Junkies

In the Moment ... June 21, 2017 Show 119 Hour 2 Dakota Political Junkies Denise Ross and Seth Tupper join us to talk...

In The Moment ... Admiral James Stavridis

In the Moment ... June 21, 2017 Show 119 Hour 1 A new book by Admiral James Stavridis seeks to understand the value...

The Latest from NPR News

What Does It Take To Move A 10-Story Tree A Couple Of City Blocks?

That answer, as seen Sunday in Boise, Idaho: $300,000 and a lot of determination. St. Luke's Health System, which...

PHOTOS: Here's How Muslims Worldwide Are Celebrating Ramadan's End

For many Muslims around the world, Sunday marks the start of Eid al-Fitr, a time of prayer and celebration. Here's a...

For Besieged Marawi Residents, A Brief Respite Ends In Gunfire

Partly to mark the end of Ramadan, the Philippine military declared a unilateral truce with ISIS-linked militants in...

These Teachers Are Learning Gun Skills To Protect Students, They Say

This week more than a dozen educators in Colorado received advanced weapons training and safety.

Inside French Prisons, A Struggle To Combat Radicalization

Some of the home-grown terrorists who have struck France in recent years were petty criminals who were radicalized...

Nobel Peace Prize Winner's Message To America: 'All Children Are Our Children'

Kaiilash Satyarthi came to Washington to encourage the U.S. government to fight for the freedom of child laborers.