What Is A Blue Moon And How Rare Are They?

Later this month, on the night of August 30-31, 2023, there will be a Super Blue Moon -- the second Supermoon of August in fact. Luna (aka Earth's Moon) will be very close to the Earth and appear along with the planet Saturn. It will also be the last Full Moon of the summer season of 2023.

How rare are Blue Moons? Well, the classic phrase "once in a Blue Moon" referring to a rare occurrence aside, Blue Moons take place in years when there are 13 Full Moons in a calendar year. The Full Moon phase occurs every 29.5 Earth days. Because of this Blue Moons occur about once every two to three years on average, although sometimes they can occur in the next year during leap years -- as will be the case in 2024, which will also have a Blue Moon in the month of August.

Although the term Blue Moon nominally refer to the second Full Moon of a single calendar month, there are actually two types of Blue Moons: a monthly Blue Moon and a seasonal Blue Moon.

The monthly Blue Moon meets the traditional definition of the second Full Moon in a single calendar month, while a seasonal Blue Moon is the third Full Moon in a season that has four Full Moons.

The Blue Moon of August 30th will be a monthly Blue Moon, since there will only be three Full Moons in summer of 2023. The next Blue Moon will take place next year -- a leap year -- on the night of August 19-20, 2024, will be a seasonal Blue Moon since there will be four Full Moons during that year's summer season: June 21st (on the summer solstice), July 21st, August 19th, and September 18th.

Finally, the term Blue Moon does not actually refer to the color of the Lunar surface itself. Moons that appear blue (such as the one in the photo above) are incredibly rare and have nothing to do with the calendar or the Moon's phases. Such coloring is usually a result of certain atmospheric conditions: smoke, dust, or even water droplets in the atmosphere from certain types of clouds can all contribute to a Full Moon taking on a blue shade on rare occasions.

Fun Full Moon Fact: The month of February will never experience a monthly Blue Moon as it only has 28 days in a common year and 29 in a leap year. Sometimes February doesn't have a Full Moon at all and this is known as a Black Moon -- which will not happen again till February of 2037.

Night Sky Photography -- 05-19-2019 -- 2019 Seasonal Blue Flower Moon & Jupiter

Good evening from upstate South Carolina, my fellow skywatchers! 

This evening, yours truly stayed up really later -- over an hour after midnight in point of fact! -- to capture a really outstanding set of images showing the Seasonal Blue Moon of 2019, along with the giant planet Jupiter close by. 

I captured these shots of the May full moon -- the Flower Moon --  near some large power lines in the foreground, including a close up of both Jupiter and the full moon. 

Now for all of y'all who are familiar with the normal term "Blue Moon" y'all know that the moon does not turn blue in point of fact. By normal term, I refer to the classic definition of a Blue Moon: the second full moon of a calendar month. Since a lunar cycle (or the time from a new moon, to a full moon, and back) lasts about 29.5 days, and most months have 30 or 31 days, inevitably there will be overlap, with the occasional calendar month including two full moons.

This is the definition that most of us are the most familiar with from the old expression, “Once in a blue moon,” which refers to the fact that this rare occurrence usually only happens every two to three years (though two of them actually happened in January & March of 2018). 

Also this definition applies to the 13th full moon in a calendar year. Since 12 lunar months only have 354 days, some years will also have 13 full moons.

However, this evening's full moon is neither of those Blue Moons. 

A Seasonal Blue Moon refers to the third full moon in an astronomical season that has four full moons. 

An astronomical season is divided by the solstices and the equinoxes -- summer solstice beginning in June, winter solstice beginning in December, spring equinox beginning in March, and fall equinox beginning in September. An astronomical season includes three months, so it would normally encompass three full moons. But since our seasons are divided by a solar calendar and not a lunar calendar, there can sometimes be overlap between lunar cycles and astronomical seasons. When this happens, and there are four full moons in an astronomical season, the third one of these is called a Seasonal Blue Moon.

It's a good thing this blogger was awake to capture it this time around since the next Seasonal Blue Moon is not due again until August 22, 2021. 

By tomorrow evening, a beautiful nearly still full Luna will move closer to Jupiter -- at least from our relative perspective here on Earth.  

Well folks, I hope y'all enjoyed my photos once again. I am headed to bed. Have a good evening and remember to keep looking to the night skies, y'all!

Night Sky Photograhy -- 01-30/31-2018 -- The Super Blue Blood Moon

Well folks, this month ends on a high note when it comes to astronomical events -- a Super Blue Blood Moon. 

On the evening of Tuesday, January 30th, the second Full Moon of the month rose just over the treetops. The second of two full moons in a calendar month is referred to as a Blue Moon, even though the moon does not technically change color. The January 31 full moon is also the third in a series of three straight full moon supermoons, or super-close full moons that I mentioned in a previous post. It’s the first of two Blue Moons in 2018, the next one will appear on March 31st.

These are the shots I took of the Super Blue Moon. I was able to get some good details, including the "Man in the Moon" and the larger craters.

 

On an interesting note, the month of February this year will have NO FULL MOON!

Luna was then partially eclipsed early the next morning on Wednesday, January 31st by the Earth's shadow across its surface. A Lunar Eclipse is also referred to as a Blood Moon, because of the deep red shadow effect across the surface. 

This trifecta of a supermoon, a blue moon, and a blood moon, are referred to as a rare Super Blue Blood Moon. 

In South Carolina, we could only see part of the Lunar Eclipse because of the position of the moon and sun, however I did manage to get a couple of pretty good shots of what we did see here in Chester County and the rest of the upstate. Only the upper left of the moon is covered in deep Earth shadow.

Folks, once again I am thankful to the Good Lord for clear skies and pleased to share these outstanding photos for y'all to enjoy. Please let me know what y'all think in the comments section below. Until next time, keep your eyes to the night skies, y'all.

Night Sky Photography - 05-21/22-2016 - Blue Moon & Bright Mars

Threatening storm clouds almost prevented me from getting some really good shots of the beautiful planetary events this weekend. Thankfully breaks in the cloud cover allowed me to get some outstanding photos after dusk both days.

The first one on Saturday, May 21st, was a great shot of the Blue Moon with the bright red Mars one day away from opposition. 

A Blue Moon does not mean that the moon itself turns blue in color. The term itself has two meanings. 

The first - and most popular in recent years - has been the second of two full moons in the same calendar month. 

The second - which more accurately fits the Blue Moon of May 21st - refers to the third full moon in a season that has four full moons. This kind of Blue Moon occurs about once every 2.7 years.

The older meaning defines a Blue Moon as the third full moon in a season that has four full moons. This kind of Blue Moon occurs about every 2.7 years. - See more at: http://www.space.com/15455-blue-moon.html#sthash.tNx6H5kl.dpuf

The older meaning defines a Blue Moon as the third full moon in a season that has four full moons. This kind of Blue Moon occurs about every 2.7 years. - See more at: http://www.space.com/15455-blue-moon.html#sthash.tNx6H5kl.dpuf

The older meaning defines a Blue Moon as the third full moon in a season that has four full moons. This kind of Blue Moon occurs about every 2.7 years. - See more at: http://www.space.com/15455-blue-moon.html#sthash.tNx6H5kl.dpuf

The Blue Moon of Saturday, May 21st rose just after 8:50 PM with the bright red planet Mars close beside it. An absolutely beautiful meeting in the heavens appeared in the eastern sky between threatening storm clouds just after dusk. 

On Sunday, May 22nd, Mars reached its opposition in Earth's night sky for the first time in over two years. It's the brightest that the Red Planet has appeared so brightly in the sky in just over 10 years because the Earth has passed between it and the sun in our smaller orbit. Hence the term: opposition. 

Martian oppositions are not the same. This is because Mars has an oblong orbit that carries the Red Planet about 26 million miles closer to the sun at perihelion (the nearest point in its orbit) than when it swings out to aphelion (the farthest point). Extra-close oppositions only occur when we go between Mars and the sun around the time Mars is closest to the sun along it's orbit. This year, Mars is closer to Earth than it has been since the opposition of November 7, 2005. Super-close oppositions of Mars only occur in periods of 15 to 17 year intervals. The last super-close Martian opposition happened on August 28, 2003, and the next one will not occur until July 27, 2018.

This year's Martian opposition puts the Red Planet at a distance of just under 47 million miles from Earth. Mars will be the closest in orbit with Earth on May 30th of this month when it will pass within 46 million miles. 

The following is the shot I managed to get of Mars in opposition just after moonrise. Little Saturn (by distance rather than actual size) can also be seen just above the treeline between Luna and the bright shinning red Mars. 

God willing if the late spring weather holds out and keeps the night showers and thunderstorms at bay, I will try to get a photo of Mars when it reaches its closest point to Earth at the end of the month.