Bill Ingalls / NASA

NASA photographer Bill Ingalls, who was in Cincinnati to take pictures during Apollo 11 moonwalker Neil Armstrong's family memorial ceremony on Aug. 31, snapped this picture of the "blue moon" hanging over the Queen City's skyline. See some of Ingalls' pictures from the memorial ceremony.

Tonight's blue moon may not be as rare as it sounds, but it's still special — as is every glorious full moon, whichever color you use to describe it.

Actually, the term "blue moon" is something of a misnomer. There's no reason for the full moon to be any bluer than usual (though it's certainly possible for the moon to take on a blue tinge). Instead, it has to do with the extra occurrence of a full moon in a given calendar cycle.

Various cultures have used different terms to describe that extra lunar cycle — Adhik Maas for Hindus, or an extra month of Adar for the Jewish calendar. The Maine Farmers' Almanac used the term "blue moon" to describe an extra moon in a particular quarter of the year.

Then, in 1946, an amateur astronomer named James Hugh Pruett wrote about the phenomenon for Sky & Telescope magazine, in the context of the old saying that a rare occurrence happened only "once in a blue moon."

Only problem was, he got it wrong.

Pruett described the blue-moon phenomenon as the second full moon in a calendar month. Sky & Telescope stuck with that, and the definition has been used (and hotly debated) ever since. If you go along with the definition, then tonight's full moon is blue due to the fact that it follows a full moon on the night of Aug. 1.

There's another long-debated issue surrounding blue moons: You could argue that they happen way too often to be considered as rare as a "blue moon" in the proverbial sense. The interplay of the lunar and solar calendars dictates that a blue moon should occur, on average, every 2.7 years.

Astrophysicist Neil deGrasse Tyson summed up the issue a couple of days ago in a Twitter update: "A month's second full moon is the blue moon. Not rare. More frequent than presidential elections, yet nobody calls them rare."

Technically speaking, the moon is already a few hours past its full phase — but it's still well worth taking note of, and not just because it's the last blue moon until July 31, 2015. It provides a fitting opportunity to pay tribute to history's first moonwalker, Neil Armstrong, who passed away last weekend. In fact, Armstrong's family is urging you to look at the moon in Neil's honor.

"The next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink," the family said.

Photographers around the world have already been getting great moon shots. Here's a sampling of the "blue moon" views:

Biswaranjan Rout / AP

A boy rides his bicycle over a stretch of sand on the outskirts of the eastern Indian city of Bhubaneswar as the "blue moon" shines above in Aug. 31.

Muhammad Hamed / Reuters

A full moon shines over Amman, the capital of Jordan, on Aug. 31.

Robert Atanasovski / AFP - Getty Images

A full moon is seen behind tree branches in the Macedonian city of Skopje on Aug. 31. According to NASA, this is the second time in August that a full moon has been seen. The first was on the night of Aug. 1-2. This phenomenon is referred to as a "blue moon."

Vesa Vauhkonen

Vesa Vauhkonen created this multiple-exposure photographic view of the moon rising over Rautalampi, Finland, on Aug. 30.

Daisuke Tomiyasu

The clouds over Kobe, Japan, take on a fittingly blue hue in this picture taken by Daisuke Tomiyasu on Aug. 31.

Louisa Gouliamaki / AFP - Getty Images

Greeks and tourists gather at the Roman Agora in Athens, which is open all night as part of a full-moon celebration on Aug. 31. A number of archaeological sites and museums around Greece opened at night, with events and concerts celebrating the second full moon of August, known as a "blue moon."

Louisa Gouliamaki / AFP - Getty Images

A picture taken on Aug. 31 shows the full moon above the ancient Acropolis hill in Athens.

Inge Harsten

Inge Harsten, who lives in Fredrikstad, Norway, used a filter to add an appropriate color to this picture of the "blue moon."

Petros Karadjias / AP

The full moon rises over the sea at Konnos beach near Ayia Napa and Protaras resort in the southeast of the island of Cyprus on Aug. 31.

For still more blue-moon pictures, check out SpaceWeather.com's photo gallery and NASA's Flickr site for blue-moon imagery. If you snap a great picture of the moon tonight, please consider sharing it with us. Use our FirstPerson upload tool to send us your moon shot, and we'll pass along a sampling of the photos we receive.

Where in the Cosmos
Vesa Vauhkonen's moonrise montage served as the subject of this week's "Where in the Cosmos" photo quiz on the Cosmic Log Facebook page. It took a while this time, but John Culp and Brian Svacina eventually guessed that the photo was taken in Finland. To reward their geographical smarts (or was it just plain luck?), I'm sending them pairs of 3-D glasses, provided courtesy of Microsoft Research's WorldWide Telescope project. Those red-blue glasses will add an extra dimension to moon pictures like this one. Got 3-D? Click the "like" button for the Cosmic Log Facebook page and get ready for next Friday's quiz.

Update for 8:20 p.m. ET: The Phrase Finder delves deeply into the origins of the phrase "blue moon," meaning a rare event, and appears to have come up with a sensible explanation. In 16th-century England, the expression was apparently used to describe an impossible event, like pigs flying. The phrase pops up in a sarcastic context in a 1528 work by William Barlow, Bishop of Chichester, titled "Treatyse of the Buryall of the Masse": "Yf they saye the mone is belewe, we must beleve that it is true."

It took centuries longer for the phrase to describe something that hasn't happened in quite a while. The Phrase Finder cites this quote in Pierce Egan's "Real Life in London" (1821): "How's Harry and Ben? — haven't seen you this blue moon." Meanwhile, the Maine Farmers' Almanac put its own astronomical twist on the term, going back to the 19th century.

More moon shots:

• Your views of the supermoon
• Slideshow: Hits from 2012's supermoon
• Darkness falls on the moon in June
• Slideshow: 50 years of moon views

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

This false-color view of Toro Crater on Mars was captured on Dec. 1, 2011, by the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter, and released on Wednesday. The different colors reflect different mineral composition on the Martian surface.

There's not much red in this picture of the Red Planet, produced by the high-resolution camera aboard NASA's Mars Reconnaissance Orbiter. Browns and blues and greens and yellows and violets ... but red? Not so much. There's a method in this colorful madness: The riot of color tells scientists that, mineralogically speaking, this is a wildly diverse region of Mars.

The orbiter took this picture of Toro Crater in Mars' northern hemisphere back on Dec. 1, and the processed version was released just this week. The University of Arizona's Alfred McEwen, principal investigator for the High Resolution Imaging Science Experiment or HiRISE, says the different colors point to different kinds of minerals that may have been altered through the action of liquid water and heat on ancient Mars.

HiRISE's views in different wavelengths can be tweaked to tell geologists things about surface composition that you might not notice in a "true color" photograph.

"In general, the blue and green colors indicate unaltered minerals like pyroxene and olivine, whereas the warmer colors indicate alteration into clays and other minerals," McEwen writes in his image advisory. "The linear north-south trending features are windblown dunes that are much younger than the bedrock."

Such hydrothermal alteration could get a closer examination elsewhere on Mars when NASA's Curiosity rover touches down in Gale Crater this August.

For more of this crazy imagery, check out this longer, higher-resolution view of the Toro Crater scene. If you've got red-blue glasses, you'll get a kick out of this 3-D version. The HiRISE home page will point you to thousands of pictures from Mars — some in true color, some in false color, some in black and white, and some in 3-D red and blue. Feel free to go crazy.

S. Robbins / Moon Mappers / CosmoQuest / NASA

This image of the moon shows craters that have been identified by citizen scientists as part of the Moon Mappers project. The blue circles indicate raw IDs by individual users, while the red circles indicate craters identified by a computer program that groups together individual markings.

Where in the Cosmos?
On the Cosmic Log Facebook page, we've been featuring a series called "Where in the Cosmos" — in which we put up a curious space picture for people to puzzle over. Last week, I posted a picture of some cratered terrain with red and blue circles all over it. It took less than 24 hours for Robert Dryden to figure out that the picture showed some of the first results from a citizen-science project called Moon Mappers.

Scientists have long studied craters on the moon to trace the evolution of the solar system. The distribution and estimated ages of lunar craters have led astronomers to conclude, for example, that the inner solar system weathered a hailstorm of impacts known as the "Late Heavy Bombardment" about 4 billion years ago.

Crater counting is a valuable exercise, but it's hard to automate. Moon Mappers, a project presented by the CosmoQuest website, is calling upon the wisdom of crowds to help scientists make sense out of the imagery being sent back to Earth by NASA's Lunar Reconnaissance Orbiter. Similar citizen-science projects, organized by Zooniverse, have yielded published research — and Moon Mappers is likely to be similarly productive. So if you want to take part in some real science, consider joining the Moon Mappers team.

The moon picture was doubly apt, because of the Moon Mappers angle as well as the past week's political debates over future moon missions. For the latest word in that debate, check out this commentary by NBC News' longtime Cape Canaveral correspondent, Jay Barbree.

I posted this week's "Where in the Cosmos" picture puzzle earlier today, and within an hour several Cosmic Log Facebookers figured out that it was a 3-D view of the Snowman crater chain on the asteroid Vesta, as seen by NASA's Dawn probe. This means that Jarin Udom, Joan Tweedell and Ryan Anthony Sebastian Carroll join Robert Dryden in the winner's circle. They're all eligible to receive 3-D glasses once I get their mailing addresses.

To get in on the next "Where in the Cosmos" puzzle, be sure to hit the "Like" button on the Cosmic Log Facebook page ... and if you're already a fan, thanks for being part of the community!

More fun with space pictures:

• Jan. 27: 3-D color map of the universe
• Jan. 20: Stephen Hawking's curios explained

Slideshow: Get an eyeful from outer space

ESO / VISTA / J. Emerson / EPA

Gaze into the Helix Nebula's golden eye and see the other cosmic highlights of January 2012.

Launch slideshow

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

Copyright John Harrison Photography

Photographer John Harrison captured this view of the Dec. 10 total solar eclipse above San Francisco's Golden Gate Bridge. "I went out at sunrise this morning not sure what to expect," he wrote. "What an awesome sight! The blue skies at sunrise with the red moon overhead were just a sight to watch. It was worth the 3 a.m. start to our fun shooting." See more of his portfolio at the John Harrison Photography website.

Millions of people witnessed today's total lunar eclipse, and that means there were plenty of cameras snapping in the darkness. We've put together this sampling from the photos submitted via FirstPerson, Facebook, Google+ and Twitter.

This was the last total solar eclipse until 2014, but there'll be plenty of other sky phenomena between now and then — including an unusual "diamond ring" annular solar eclipse next May, a Venus transit in June, a total solar eclipse in November, and meteor showers galore. Please keep us in mind whenever you've got a cool picture of the cosmos, and thanks for passing along slick eclipse pics like these:

Humza Mehbub

Humza Mehbub sent this composite image of the lunar eclipse from Lahore, Pakistan. The multiple exposures show Earth's shadow creeping across the moon's disk from 5:30 p.m. to 7:30 p.m. in Lahore, when the eclipse hit its peak.

Anthony Citrano

Anthony Citrano, a fashion photographer from Venice, Calif., captured this pre-dawn view of the eclipse as seen over Malibu and the Santa Monica Mountains. "Before going to bed at 1 a.m. ... I considered setting my alarm to get up and shoot the eclipse," Citrano wrote. "I was feeling quite tired - and lazily decided not to set the alarm. But my subconscious mind was determined, because I nevertheless awoke four hours later. I got out of bed, looked out the window, and it was just starting to go into shadow. I shot a few hand-held shots from my home in Venice - and then hopped in the car and drove the mile or two to the Santa Monica bluffs. This shot is the result. ... Running out the door I didn't notice I was traveling with a nearly-dead battery - and no spares - and this lens is really hard on power. I ran out of juice just after this shot, so I'm glad I got it." To learn more about Citrano's day job, check out his portfolio at Zigzag Lens.

Daniel Fischer

German science writer Daniel Fischer captured this picture of the total eclipse during a trip to Ranihet, India. "Took a lot of pictures with different settings, as a guide for the next total lunar eclipse - which, unfortunately, is now 3 years away." For more, check out Fischer's Twitpic gallery and his Cosmic Mirror website.

Michael Zeiler

Cartographer Michael Zeiler sent in this composite photo that captures the last partial stages of the lunar eclipse as seen from Los Alamos, N.M. "Total lunar eclipse began two minutes after sunrise where I live," Zeiler wrote. "I tried to capture a photograph of the selenelion, but missed it by a couple of minutes." Zeiler's website is the aptly named Eclipse-Maps.com, and he has produced charts for the May annular solar eclipse as well as the November total solar eclipse. "My map of the transit of Venus is on page 70 of the January 2012 Sky and Telescope," he says.

Jim Werle

The lunar eclipse competes with the bright lights of Las Vegas in this photo from Jim Werle.

JoAnne and Michael Schnyder

JoAnne and Michael Schnyder sent this picture of the partial eclipse from Cape Verde, Ariz. This was the view at 6:45 a.m. MT, at a stage when Earth's shadow hadn't yet completely covered the moon's disk but you could already make out the reddish eclipse glow.

Adam Gray

For some observers in the western U.S., the eclipse provided the seemingly impossible opportunity to catch the sunrise and the moonset simultaneously - a phenomenon known as "selenelion." Adam Gray sent in these two photos that show the brightening sunrise sky in the east and the darkening moon in the west. "The marine layer started to roll in right at about the time of totality," Gray wrote.

This eclipse preview story provides further explanation of the "impossible" selenelion phenomenon (alternate spelling is "selenehelion"). While we're on the subject of selenelion, toy inventor Mark Burginger sent in a couple of photos from the parking lot at Tetherow Golf Course in Bend, Ore., that shows the eastward sunrise view as well as the westward lunar eclipse view.

Follow the links below to see eclipse photos from:

• C.J. Cassarino of Livermore, Calif.
• Dale Cunningham of Corona, Calif.
• Barbara Hewitt of San Marcos, Calif.
• Joe Leonard of Taos, N.M.
• Fran Pepoon of Roseville, Calif.
• Anthony Wells from Hawaii

Thanks again to these photographers as well as others who submitted eclipse pics. For still more about today's event and other eclipses, check out these links:

• PhotoBlog gallery of lunar and solar eclipses
• Interactive: What causes a lunar eclipse?
• Nine cool facts about the lunar eclipse
• Why an eclipse paints the moon red

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

ESO / Igor Chekalin

This image of the Orion Nebula was captured using the Wide Field Imager camera on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile. This image is a composite of several exposures taken through five different filters. The exposure times were about 52 minutes through each filter.

The Orion Nebula is one of the best-known star-forming regions in our celestial neighborhood, but astronomers can still find some "hidden treasures" if they just look at the nebula in a different light.

Case in point: this ethereal picture of the Orion Nebula, featured today by the European Southern Observatory in Chile. The image is based on data from the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile, and submitted by Russia's Igor Chekalin for the ESO's Hidden Treasures astrophotography competition. This particular image took seventh place. Another one of Chekalin's entries, showing the M78 reflection nebula in Orion, won first prize (and earned Chekalin a trip to Chile).

The Orion Nebula, also known as M42, is a huge complex of gas and dust where massive stars are constantly being squeezed into existence. It's about 1,350 light-years away, which is pretty close by astronomical standards. You've probably already figured out that the nebula is in the constellation Orion, which is at center stage in the night sky at this time of year.

The hidden treasures that Chekalin found were data sets from roughly 52-minute exposures taken in five different wavelengths. The rays of light that passed through a red filter and through a filter sensitive to glowing hydrogen gas are represented as red in this image. Light in the yellow-green part of the spectrum is shown here as green. The blue-filter image is reproduced as blue, and ultraviolet shows up as purple. The result is a beautiful picture that sheds new light on the nebula's gauzy structure.

For additional perspectives, check out this ESO vidcast from last year, which compares infrared and visible-light imagery of the Orion Nebula:

The infrared-vs.-visible view is a major focus for NASA researchers using the brand-new Stratospheric Observatory for Infrared Astronomy, or SOFIA. During last week's winter meeting of the American Astronomical Society in Seattle, the researchers in charge of SOFIA's airborne telescope showed off an infrared mosaic image of the Orion Nebula that was captured during their "Short Science 1" observing program in December.

Infrared-sensitive telescopes are particularly good at tracing the structures within dusty star-forming regions. Here's a comparison of the Hubble Space Telescope's visible-light view (left), ESO's near-infrared view (middle) and SOFIA's mid-infrared view (right):

NASA

These images show the Orion Nebula as seen by the Hubble Space Telescope in visible light (left), the European Southern Observatory in near-infrared wavelengths (middle) and the SOFIA airborne observatory in mid-infrared wavelengths (right). Credits for the visible-light image: NASA/ESA/HST/AURA/STScI/O'Dell & Wong. Near-infrared image: ESO/McCaughrean et al. Mid-infrared image: NASA/DLR/SOFIA/USRA/DSI/FORCAST Team.

The dense cloud of interstellar dust at upper left is completely opaque in visible light, partially transparent in the near-infrared and glowing with heat in the mid-infrared. Dust-shrouded stars can easily be seen shining at upper right in the mid-infrared, but they're less apparent in the near-infrared and completely hidden in visible light. In contrast, the hot stars of the Trapezium Cluster sparkle in visible light and near-infrared, but are barely visible in SOFIA's mid-infrared view.

For astronomers, this isn't just a game of hide-and-seek. Comparing different views, in different wavelengths, is how scientists figure out what's going on deep within distant nebulas and galaxies. The scientific insights gained through such comparisons are the true "hidden treasures" of the cosmos.

More wonders in multiple wavelengths:

• Telescopes do a triple take
• Hubble's new superpowers
• Scientists team up on telescopes
• 10 Hubble targets you can find too

Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle). Boyle has also written a book about Pluto as well as the past and present search for planets. To learn more, click your way to the website for "The Case for Pluto."