This map shows the 23% illuminated crescent Moon from the central U.S. around 10:00 UT Friday morning. Observers who start observing earlier may also see stars in the Hyades cluster occulted. Credit: Stellarium
We’re in for a celestial show from two of the sky’s glitterati this week. On Friday morning July 29 around 10:00 UT (5 a.m. CDT), the crescent Moon will occult the star Aldebaran from the eastern and southern U.S. south of a line from Toledo, Ohio through St. Louis, Tulsa and El Paso, Texas. North of that line, the Moon will slide just south of the star in a spectacular conjunction. But the real action lies within a half-mile of either side of the line, where lucky observers will see a grazing occultation.
Use this map to help you plan your occultation adventure. Much of North and South America will see a wonderful conjunction, while many areas will witness the occultation. If you can drive to the graze line, do it! Credit: David Dunham
As the Moon’s orbital motion carries it eastward at the rate of one lunar diameter per hour, Aldebaran will appear to approach the sunlit northern cusp and then scrape along the Moon’s northern limb. You’ll need binoculars or a small telescope to see the initial approach, but once star reaches the semi-dark, earthlit portion of the Moon, the graze will be visible with the naked eye.
This diagram shows the the grazing path of Aldebaran. As the Moon moves east, the star will appear to move to the right or west. Be sure not to miss it — the entire grazing event lasts just 3 minutes. Credit: David Dunham
The edge or limb of the Moon appears smooth to the eye, but it’s rife with polar mountain peaks. As Aldebaran creeps along the craggy limb, it will repeatedly flash in and out of view as peaks and cliffs momentarily block it from sight. And here’s the truly amazing thing. Observers along the western section of the graze line, where the event takes place in fairly dark sky, can watch the star blink in and out of view without optical aid when it reaches the dark part of the lunar disk. Wow!
Aldebaran’s large size means it won’t disappear instantaneously when it’s covered either by the lunar limb during occultation or by mountains along the grazing path. Credit: Wikipedia
Aldebaran is no small star. An orange giant 67 light years from Earth, it’s 44 times the diameter of the Sun. That means that sometimes only a part of the star at a time will covered at a time in some cases, so the length of the flashes will vary. According to David Dunham, president of the International Occultation Timing Association (IOTA), Aldebaran will disappear for one-tenth of a second up to a second as the Moon rolls east, allowing some observers to sense the size of the star. Wow x 100!
Aldebaran hangs near the edge of the moon two minutes before it was occulted last October in this photo taken with a smartphone. The star was easily visible through the telescope. Credit: Bob King
Skywatchers further east along the graze line and in other areas where the occultation / conjunction takes place after sunrise shouldn’t pass up the chance to see the event. During last October’s occultation of Aldebaran, I was able to see and photograph the star in my 10-inch scope in daylight no problem. The moon will be closer to the Sun this time around, but give it try anyway. This is the best grazing occultation of Aldebaran visible from North America in the current 4-year series.
For the many who live either north or south of the graze line, the views will still be fantastic. You’ll either see an occultation and subsequent reappearance of the star at the dark limb … or a fine conjunction. The forecast looks good for my city, so I plan on heading out to watch an orange giant meet the skinny Moon. I wish you clear skies and happy shooting!
For more information about the event including detailed weather forecasts and grazing maps, check out the IOTA’s public announcement page. Click here for Universal Times for the disappearance and reappearance of the star for over 1,000 cities.
The first liquid hydrogen tank, also called the qualification test article, for NASA's new Space Launch System (SLS) heavy lift rocket lies horizontally beside the Vertical Assembly Center robotic weld machine on July 22, 2016 after final welding was just completed at NASA’s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer/kenkremer.com
The first liquid hydrogen tank, also called the qualification test article, for NASA’s new Space Launch System (SLS) heavy lift rocket lies horizontally beside the Vertical Assembly Center robotic weld machine on July 22, 2016 after final welding was just completed at NASA’s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer/kenkremer.com
MICHOUD ASSEMBLY FACILITY, NEW ORLEANS, LA – NASA has just finished welding together the very first fuel tank for America’s humongous Space Launch System (SLS) deep space rocket currently under development – and Universe Today had an exclusive up close look at the liquid hydrogen (LH2) test tank shortly after its birth as well as the first flight tank, during a tour of NASA’s New Orleans rocket manufacturing facility on Friday, July 22, shortly after completion of the milestone assembly operation.
“We have just finished welding the first liquid hydrogen qualification tank article …. and are in the middle of production welding of the first liquid hydrogen flight hardware tank [for SLS-1] in the big Vertical Assembly Center welder!” explained Patrick Whipps, NASA SLS Stages Element Manager, in an exclusive hardware tour and interview with Universe Today on July 22, 2016 at NASA’s Michoud Assembly Facility (MAF) in New Orleans.
“We are literally putting the SLS rocket hardware together here at last. All five elements to put the SLS stages together [at Michoud].”
This first fully welded SLS liquid hydrogen tank is known as a ‘qualification test article’ and it was assembled using basically the same components and processing procedures as an actual flight tank, says Whipps.
“We just completed the liquid hydrogen qualification tank article and lifted it out of the welding machine and put it into some cradles. We will put it into a newly designed straddle carrier article next week to transport it around safely and reliably for further work.”
And welding of the liquid hydrogen flight tank is moving along well.
“We will be complete with all SLS core stage flight tank welding in the VAC by the end of September,” added Jackie Nesselroad, SLS Boeing manager at Michoud. “It’s coming up very quickly!”
“The welding of the forward dome to barrel 1 on the liquid hydrogen flight tank is complete. And we are doing phased array ultrasonic testing right now!”
SLS is the most powerful booster the world has even seen and one day soon will propel NASA astronauts in the agency’s Orion crew capsule on exciting missions of exploration to deep space destinations including the Moon, Asteroids and Mars – venturing further out than humans ever have before!
The LH2 ‘qualification test article’ was welded together using the world’s largest welder – known as the Vertical Assembly Center, or VAC, at Michoud.
And it’s a giant! – measuring approximately 130-feet in length and 27.6 feet (8.4 m) in diameter.
See my exclusive up close photos herein documenting the newly completed tank as the first media to visit the first SLS tank. I saw the big tank shortly after it was carefully lifted out of the welder and placed horizontally on a storage cradle on Michoud’s factory floor.
The newly assembled first liquid hydrogen tank, also called the qualification test article, for NASA’s new Space Launch System (SLS) heavy lift rocket lies horizontally beside the Vertical Assembly Center robotic weld machine (blue) on July 22, 2016. It was lifted out of the welder (top) after final welding was just completed at NASA’s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer/kenkremer.com
Finishing its assembly after years of meticulous planning and hard work paves the path to enabling the maiden test launch of the SLS heavy lifter in the fall of 2018 from the Kennedy Space Center (KSC) in Florida.
The qual test article is the immediate precursor to the actual first LH2 flight tank now being welded.
“We will finish welding the liquid hydrogen and liquid oxygen flight tanks by September,” Whipps told Universe Today.
Up close view of the dome of the newly assembled first ever liquid hydrogen test tank for NASA’s new Space Launch System (SLS) heavy lift rocket on July 22, 2016 after it was welded together at NASA’s Michoud Assembly Facility in New Orleans. Sensors will be attached to both ends for upcoming structural loads and proof testing. Credit: Ken Kremer/kenkremer.com
Technicians assembled the LH2 tank by feeding the individual metallic components into NASA’s gigantic “Welding Wonder” machine – as its affectionately known – at Michoud, thus creating a rigid 13 story tall structure.
The welding work was just completed this past week on the massive silver colored structure. It was removed from the VAC welder and placed horizontally on a cradle.
I watched along as the team was also already hard at work fabricating SLS’s first liquid hydrogen flight article tank in the VAC, right beside the qualification tank resting on the floor.
Welding of the other big fuel tank, the liquid oxygen (LOX) qualification and flight article tanks will follow quickly inside the impressive ‘Welding Wonder’ machine, Nesselroad explained.
The LH2 and LOX tanks sit on top of one another inside the SLS outer skin.
The SLS core stage – or first stage – is mostly comprised of the liquid hydrogen and liquid oxygen cryogenic fuel storage tanks which store the rocket propellants at super chilled temperatures. Boeing is the prime contractor for the SLS core stage.
To prove that the new welding machines would work as designed, NASA opted “for a 3 stage assembly philosophy,” Whipps explained.
Engineers first “welded confidence articles for each of the tank sections” to prove out the welding techniques “and establish a learning curve for the team and test out the software and new weld tools. We learned a lot from the weld confidence articles!”
“On the heels of that followed the qualification weld articles” for tank loads testing.
“The qualification articles are as ‘flight-like’ as we can get them! With the expectation that there are still some tweaks coming.”
“And finally that leads into our flight hardware production welding and manufacturing the actual flight unit tanks for launches.”
“All the confidence articles and the LH2 qualification article are complete!”
What’s the next step for the LH2 tank?
The test article tank will be outfitted with special sensors and simulators attached to each end to record reams of important engineering data, thereby extending it to about 185 feet in length.
Thereafter it will loaded onto the Pegasus barge and shipped to NASA’s Marshall Space Flight Center in Huntsville, Alabama, for structural loads testing on one of two new test stands currently under construction for the tanks. The tests are done to prove that the tanks can withstand the extreme stresses of spaceflight and safely carry our astronauts to space.
“We are manufacturing the simulators for each of the SLS elements now for destructive tests – for shipment to Marshall. It will test all the stress modes, and finally to failure to see the process margins.”
NASA’s Space Launch System (SLS) blasts off from launch pad 39B at the Kennedy Space Center in this artist rendering showing a view of the liftoff of the Block 1 70-metric-ton (77-ton) crew vehicle configuration. Credit: NASA/MSFC
The SLS core stage builds on heritage from NASA’s Space Shuttle Program and is based on the shuttle’s External Tank (ET). All 135 ET flight units were built at Michoud during the thirty year long shuttle program by Lockheed Martin.
“We saved billions of dollars and years of development effort vs. starting from a clean sheet of paper design, by taking aspects of the shuttle … and created an External Tank type generic structure – with the forward avionics on top and the complex engine section with 4 engines (vs. 3 for shuttle) on the bottom,” Whipps elaborated.
“This is truly an engineering marvel like the External Tank was – with its strength that it had and carrying the weight that it did. If you made our ET the equivalent of a Coke can, our thickness was about 1/5 of a coke can.”
“It’s a tremendous engineering job. But the ullage pressures in the LOX and LH2 tanks are significantly more and the systems running down the side of the SLS tank are much more sophisticated. Its all significantly more complex with the feed lines than what we did for the ET. But we brought forward the aspects and designs that let us save time and money and we knew were effective and reliable.”
The Vertical Weld Center tool used to fabricate barrel segments for the SLS liquid hydrogen and oxygen core stage tanks via vertical friction stir welding operations at NASA’s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer/kenkremer.com
The SLS core stage is comprised of five major structures: the forward skirt, the liquid oxygen tank (LOX), the intertank, the liquid hydrogen tank (LH2) and the engine section.
The LH2 and LOX tanks feed the cryogenic propellants into the first stage engine propulsion section which is powered by a quartet of RS-25 engines – modified space shuttle main engines (SSMEs) – and a pair of enhanced five segment solid rocket boosters (SRBs) also derived from the shuttles four segment boosters.
The tanks are assembled by joining previously manufactured dome, ring and barrel components together in the Vertical Assembly Center by a process known as friction stir welding. The rings connect and provide stiffness between the domes and barrels.
The LH2 tank is the largest major part of the SLS core stage. It holds 537,000 gallons of super chilled liquid hydrogen. It is comprised of 5 barrels, 2 domes, and 2 rings.
The LOX tank holds 196,000 pounds of liquid oxygen. It is assembled from 2 barrels, 2 domes, and 2 rings and measures over 50 feet long.
The material of construction of the tanks has changed compared to the ET.
“The tanks are constructed of a material called the Aluminum 2219 alloy,” said Whipps. “It’s a ubiquosly used aerospace alloy with some copper but no lithium, unlike the shuttle superlightweight ET tanks that used Aluminum 2195. The 2219 has been a success story for the welding. This alloy is heavier but does not affect our payload potential.”
“The intertanks are the only non welded structure. They are bolted together and we are manufacturing them also. It’s much heavier and thicker.”
Overall, the SLS core stage towers over 212 feet (64.6 meters) tall and sports a diameter of 27.6 feet (8.4 m).
NASA’s Vehicle Assembly Center is the world’s largest robotic weld tool. The domes and barrels are assembled from smaller panels and piece parts using other dedicated robotic welding machines at Michoud.
The total weight of the whole core stage empty is 188,000 pounds and 2.3 million pounds when fully loaded with propellant. The empty ET weighed some 55,000 pounds.
Considering that the entire Shuttle ET was 154-feet long, the 130-foot long LH2 tank alone isn’t much smaller and gives perspective on just how big it really is as the largest rocket fuel tank ever built.
“So far all the parts of the SLS rocket are coming along well.”
“The Michoud SLS workforce totals about 1000 to 1500 people between NASA and the contractors.”
Every fuel tank welded together from now on after this series of confidence and qualification LOX and LH2 tanks will be actual flight article tanks for SLS launches.
“There are no plans to weld another qualification tank after this,” Nesselroad confirmed to me.
What’s ahead for the SLS-2 core stage?
“We start building the second SLS flight tanks in October of this year – 2016!” Nesselroad stated.
The world’s largest welder was specifically designed to manufacture the core stage of the world’s most powerful rocket – NASA’s SLS.
The Vertical Assembly Center welder was officially opened for business at NASA’s Michoud Assembly Facility in New Orleans on Friday, Sept. 12, 2014.
NASA Administrator Charles Bolden was personally on hand for the ribbon-cutting ceremony at the base of the huge VAC welder.
The state-of-the-art welding giant stands 170 feet tall and 78 feet wide. It complements the world-class welding toolkit being used to assemble various pieces of the SLS core stage including the domes, rings and barrels that have been previously manufactured.
The Gore Weld Tool (foreground) and Circumferential Dome Weld Tool (background) used to fabricate dome segments for the SLS liquid hydrogen and oxygen core stage tanks via vertical friction stir welding operations at NASA’s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer/kenkremer.com
The maiden test flight of the SLS/Orion is targeted for no later than November 2018 and will be configured in its initial 70-metric-ton (77-ton) Block 1 configuration with a liftoff thrust of 8.4 million pounds – more powerful than NASA’s Saturn V moon landing rocket.
Although the SLS-1 flight in 2018 will be uncrewed, NASA plans to launch astronauts on the SLS-2/EM-2 mission slated for the 2021 to 2023 timeframe.
The exact launch dates fully depend on the budget NASA receives from Congress and who is elected President in the November 2016 election – and whether they maintain or modify NASA’s objectives.
“If we can keep our focus and keep delivering, and deliver to the schedules, the budgets and the promise of what we’ve got, I think we’ve got a very capable vision that actually moves the nation very far forward in moving human presence into space,” said William Gerstenmaier, associate administrator for the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington, during the post QM-2 SRB test media briefing in Utah last month.
“This is a very capable system. It’s not built for just one or two flights. It is actually built for multiple decades of use that will enable us to eventually allow humans to go to Mars in the 2030s.”
Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Learn more about SLS and Orion crew vehicle, SpaceX CRS-9 rocket launch, ISS, ULA Atlas and Delta rockets, Juno at Jupiter, Orbital ATK Antares & Cygnus, Boeing, Space Taxis, Mars rovers, NASA missions and more at Ken’s upcoming outreach events:
July 27-28: “ULA Atlas V NRO Spysat launch July 28, SpaceX launch to ISS on CRS-9, SLS, Orion, Juno at Jupiter, ULA Delta 4 Heavy NRO spy satellite, Commercial crew, Curiosity explores Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
Graphic shows all the dome, barrel, ring and engine components used to assemble the five major structures of the core stage of NASA’s Space Launch System (SLS) in Block 1 configuration. Credits: NASA/MSFCAt NASA’s Michoud Assembly Facility in New Orleans, Patrick Whipps/NASA SLS Stages Element Manager and Ken Kremer/Universe Today discuss details of SLS manufacture by the Circumferential Dome Weld Tool used to fabricate dome segments for the SLS liquid hydrogen and oxygen core stage tanks. Credit: Ken Kremer/kenkremer.comGraphic shows Block I configuration of NASA’s Space Launch System (SLS). Credits: NASA/MSFC
A photo of the full moon, taken from Apollo 11 on its way home to Earth, from about 18,520 km (10,000 nm) away. Credit: NASA
The asteroid that punched an “eye” in the Moon is about 10 times more massive than originally thought. Researchers say a protoplanet-sized body slammed into the Moon about 3.8 billion years ago, creating the area called Imbrium Basin that forms the right eye of the so-called “Man in the Moon.” Additionally, this large body also indicates that protoplanet-sized asteroids may have been common in the early solar system, putting the “heavy” into the Late Heavy Bombardment.
“We show that Imbrium was likely formed by an absolutely enormous object, large enough to be classified as a protoplanet,” said Pete Schultz from Brown University. “This is the first estimate for the Imbrium impactor’s size that is based largely on the geological features we see on the Moon.”
Mare Imbrium or the Sea of Showers is highlighted in this map of the moon. The other large, dark spots are also basins created from asteroid impacts. Credit: NASA
The Imbrium Basin is easily seen when the Moon is full, as a dark patch in the Moon’s northwestern quadrant. It is about 750 miles across, and a closer look shows the basin is surrounded by grooves and gashes that radiate out from the center of the basin, plus a second set of grooves with a different alignment that have puzzled astronomers for decades.
To re-enact the impact, Schultz used the Vertical Gun Range at the NASA Ames Research Center to conduct hypervelocity impact experiments. This facility has a 14-foot cannon that fires small projectiles at up to 25,750 km/hr (16,000 miles per hour), and high-speed cameras record the ballistic dynamics. During his experiments, Schultz noticed that in addition to the usual crater ejecta from the impact, the impactors themselves – if large enough — had a tendency to break apart when they first made contact with the surface. Then these chunks would continue to travel at a high speeds, skimming along and plowing across the surface, creating grooves and gouges.
Grooves and gashes associated with the Imbrium Basin on the Moon have long been puzzling. New research shows how some of these features were formed and uses them to estimate the size of the Imbrium impactor. The study suggests it was big enough to be considered a protoplanet. NASA/Northeast Planetary Data Center/Brown University
The results showed the second set of grooves were likely formed by these large chunks of the impactor that sheared off on initial contact with the surface.
“The key point is that the grooves made by these chunks aren’t radial to the crater,” Schultz said in a press release. “They come from the region of first contact. We see the same thing in our experiments that we see on the Moon — grooves pointing up-range, rather than the crater.”
The second set of groove trajectories could be used to estimate the impactor’s size. Schultz worked with David Crawford of the Sandia National Laboratories to generate computer models of the physics of various sizes of impactors, and they were able to estimate the impactor that created Imbrium Basin to be more than 250 km (150 miles) across, which is two times larger in diameter and 10 times more massive than previous estimates. This puts the impactor in the range of being the size of a protoplanet.
“That’s actually a low-end estimate,” Schultz said. “It’s possible that it could have been as large as 300 kilometers.”
Previous estimates, Schultz said, were based solely on computer models and yielded a size estimate of only about 50 miles in diameter.
Schultz and his colleagues also used the same methods to estimate the sizes of impactors related to several other basins on the Moon, for example, the Moscoviense and Orientale basins on the Moon’s far side, which yielded impactor sizes of 100 and 110 kilometers across respectively, larger than some previous estimates.
Combining these new estimates with the fact that there are even larger impact basins on the Moon and other planets, Schultz concluded that protoplanet-sized asteroids may have been common in the early solar system, and he called them the “lost giants” of the Late Heavy Bombardment, a period of intense comet and asteroid bombardment thought to have pummeled the Moon and all the planets including the Earth about 4 to 3.8 billion years ago.
“The Moon still holds clues that can affect our interpretation of the entire solar system,” he said. “Its scarred face can tell us quite a lot about what was happening in our neighborhood 3.8 billion years ago.”
Buzz Aldrin Gazes at Tranquility Base during the Apollo 11 moonwalk in an image taken by Neil Armstrong. Credit: NASA
Looking for a way to commemorate the 47th anniversary of the Apollo 11 mission landing on the Moon? Here are a few different ways look back on this historic event and take advantage of advances in technology or new data.
Below is a video that uses data from the Lunar Reconnaissance Orbiter and its amazing suite of cameras, offering a side-by-side view of Apollo 11’s descent, comparing footage originally shot from the Eagle lunar module’s window with views created from reconstructed LRO imagery. This is a fun way to re-live the landing — 1202 alarms and all — while seeing high definition views of the lunar surface.
The National Air and Space Museum in Washington, DC has a special way to mark the Apollo 11 anniversary. They have posted online high-resolution 3-D scans of the command moduleColumbia, the spacecraft that carried astronauts Neil Armstrong, Buzz Aldrin and Michael Collins to the Moon. This very detailed model allows you to explore the entire spacecraft’s interior, which, if you’ve ever visited the Air & Space museum and seen Columbia in person, you probably know is a tremendous ‘upgrade,’ since you can only see a portion of the interior through couple of small hatches and windows. The Smithsonian is also making the data files of the model available for download so it can be 3-D printed or viewed with virtual-reality goggles. Find all the details here.
While 3D scanning the Apollo 11 Command Module, museum staff uncovered writing on the interior walls of the module.The main control panel of the spacecraft contains essential switches and indicators that had to be referred to and operated during the most crucial aspects of the flight. Numbers and references written by hand onto the panel can be checked against the audio and written transcripts from the mission to provide a more vivid picture of just what transpired. Credit: Smithsonian Institution.
Here’s a remastered version of the original mission video as aired in July 1969 depicting the Apollo 11 astronauts conducting several tasks during the moonwalk (EVA) operations on the surface of the moon, which lasted approximately 2.5 hours.
If you’re pressed for time, here’s a quick look at the entire Apollo 11 mission, all in just 100 seconds from Spacecraft Films:
Here’s a very cool detailed look at the Apollo 11 launch in ultra-slow motion, with narration:
NASA's Deep Space Climate Observatory captured a series of images of the Moon passing in front of the Earth on July 5th. Image: NASA/NOAA
We’re accustomed to seeing stunning images of both the Moon and Earth floating in space. It’s the age we live in. But seeing them together is rare. Now, NASA’s Deep Space Climate Observatory (DSCOVR) has captured images of the Moon passing between itself and the Earth, in effect photo-bombing Earth.
The image was captured with the Earth Polychromatic Imaging Camera (EPIC) camera on DISCOVR, and is the second time this has been captured. EPIC is a 4 megapixel camera on board DSCOVR, and DSCOVR is in orbit about 1.6 million km (1 million miles) from Earth, between the Earth and the Sun.
“For the second time in the life of DSCOVR, the moon moved between the spacecraft and Earth,” said Adam Szabo, DSCOVR project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Cool pictures of the Moon are a bonus, though, as DSCOVR’s primary mission is to monitor the solar wind in real time for the National Oceanic and Atmospheric Administration (NOAA). It does so while inhabiting the first LaGrange point between the Earth and the Sun, where the gravitational pull of the Sun and the Earth balance each other. To do so requires a complex orbit called a Lissajous orbit, a non-recurring orbit which takes DSCOVR from an ellipse to a circle and back.
DSCOVR occupies the LaGrange point 1 between the Earth and the Sun. Image: NOAA
DSCOVR has other important work to do. From its vantage point, DSCOVR keeps a constantly illuminated view of the surface of the Earth as it rotates. DSCOVR provides observations of cloud height, vegetation, ozone, and aerosols in the atmosphere. This is important scientific data in monitoring and understanding Earth’s climate.
DSCOVR is a partnership between NASA, NOAA and the U.S. Air Force. As mentioned above, its primary objective is maintaining the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA. The DSCOVR website also has daily color pictures of the Earth, for all your eye-candy needs.
Do you see the 'Lunar W,' just below Mons Rümker on the lunar limb? Image credit: Apollo 15/NASA
Ready for some astro-pareidolia? This week, we look no further than Earth’s Moon, which reaches 1st Quarter phase this coming Sunday.
The Moon reaches First Quarter phase for lunation 1156 (which dates synodic cycles of the Moon using what’s called the Brown Lunation Number all the way back to January 17, 1923) this weekend on Sunday, June 12th, at 9:10 EDT/13:10 UT.
Every culture sees something different in the face of the Moon. The Chinese saw a rabbit, and named the Yutu ‘Jade Rabbit’ rover in honor of the myth. In Longfellow’s The Song of Hiawatha, it’s the body of the Iroquois Indian chief’s grandmother we see, flung up against the Moon. The Greeks believed the Moon was a large polished mirror, reflecting back a view of the Earth below. Of course, if this were the case, it would be hard to explain just how the image doesn’t shift during the night, as the Moon moves across the sky.
The annotated features on the lunar nearside. Image credit: Wikimedia Commons/ Peter Freiman(Cmglee). Background photograph by Gregory H. Revera.
A cosmic Rorschach test, the Moon is tidally locked in the Earth’s embrace, keeping its far side forever hidden from our terrestrial vantage point. The subtle rocking motions known as libration and nutation allow us to peer over the edge just a bit, allowing us to see 59% of the Moon’s total surface. A glimpse of the far side had to wait until the Soviet Luna 3 spacecraft flew past the Moon on October 7th, 1959 and returned the first blurry images.
One of the most famous of the lunar letters is the Lunar X, also referred to as the Werner X or Purbach Cross. This is the confluence of the rims of the craters La Caille, Blanchinus and Purbach located in the lunar highlands. The Lunar X becomes visible as the waxing gibbous Moon reaches seven days illumination, about 6 to 10 hours (depending on the incident sun angle) after First Quarter phase, and 6 to 10 hours before Last Quarter. The Lunar X can stand out in dramatic contrast against the darkness just beyond the lunar terminator, if you can catch it just as the first rays of sunlight hits the top of the ridge. Remember, the span of sunrise to sunset lasts two weeks on the Moon, and looking Earthward, you’d see the Earth in an opposite phase.
All hail the ‘Lunar X’… image credit: Dave Dickinson.
Sometimes, the Curtiss Cross feature is referred to as a lesser known Lunar X; the confluence of two or more crater rims on the battered surface of the Moon is far from uncommon.
The Lunar X and the Lunar V features. Image credit and copyright: Mary Spicer
Sweeping northward, the Lunar V feature in the Mare Vaporum is also sometimes prominent around the same time as the Lunar X, and it’s possible to nab both in the same image.
Other lunar letters of note include the Lunar S in Sinus Asperitatis (visible at 47% illumination just before First Quarter), the Lunar W located near Mons Rümker on the lunar limb in the Oceanus Procellarum, and our favorite of the lesser known lunar letters, the Lunar Q of crater Kies in the Mare Nubium reaching favorable illumination 10 days after New. You can see a partial listing of lunar letters in the WikiMoon article here.
The ‘Lunar Q’ feature… Image credit: NASA/LROC.
Of course, circular craters provide a wealth of candidates for the ‘Lunar O,’ and straight line features such as the Rupes Recta lunar straight wall feature in the Mare Nubium could easily pass for the ‘Lunar I’. Veteran lunar observer Charles Wood made a call in Sky and Telescope magazine to fill out the visual lunar alphabet in a similar fashion akin to Galaxy Zoo… hey, who wouldn’t love to spell out their name in craters? Maybe some of the recently mapped worlds such as Mercury, Pluto or Ceres could come to the rescue, filling in the final letters?
Many of these are optical illusions, tricks of lighting as the angle of the rising Sun slowly changes, casting shadows across the lunar landscape. Two illumination effects that are at work here straight out of art class are what’s known as the Clair-obscur or chiaroscuro phenomenon of light and shadow, and the Trompe l’Oeil effect, a three-dimension illusion of forced perspective. Follow features such as the Lunar X night to night as the Moon heads towards Full, and you’ll notice they nearly vanish amid the glare, as the Sun shines down from high overhead. The vanishing ‘face on Mars‘ was the result of the same trick of light seen in the early Viking 1 orbiter images. The ‘face’ vanished once the Mars Global Surveyor re-imaged the region during a pass at near-full illumination in 2001. Hey, why don’t conspiracy theorists ever cite the ‘Man in the Moon‘ as an artificial construct?
Why lunar letters? Well, I think its neat, to see something as familiar yet improbable as a gleaming letter on the lunar surface staring back at you at the eyepiece. If you look long and hard enough, the universe will produce just about anything, including telescope-building primates with language, and an accidental alphabet written in the heavens.
New research finds that asteroids delivered as much 80 percent of the Moon's water. Credit: LPI/David A. Kring
Over the course of the past few decades, our ongoing exploration the Solar System has revealed some surprising discoveries. For example, while we have yet to find life beyond our planet, we have discovered that the elements necessary for life (i.e organic molecules, volatile elements, and water) are a lot more plentiful than previously thought. In the 1960’s, it was theorized that water ice could exist on the Moon; and by the next decade, sample return missions and probes were confirming this.
Since that time, a great deal more water has been discovered, which has led to a debate within the scientific community as to where it all came from. Was it the result of in-situ production, or was it delivered to the surface by water-bearing comets, asteroids and meteorites? According to a recent study produced by a team of scientists from the UK, US and France, the majority of the Moon’s water appears to have come from meteorites that delivered water to Earth and the Moon billions of years ago.
For the sake of their study, which appeared recently in Nature Communications, the international research team examined the samples of lunar rock and soil that were returned by the Apollo missions. When these samples were originally examined upon their return to Earth, it was assumed that the trace of amounts of water they contained were the result of contamination from Earth’s atmosphere since the containers in which the Moon rocks were brought home weren’t airtight. The Moon, it was widely believed, was bone dry.
The blue areas show locations on the Moon’s south pole where water ice is likely to exist. Credit: NASA/GSFC
However, a 2008 study revealed that the samples of volcanic glass beads contained water molecules (46 parts per million), as well as various volatile elements (chlorine, fluoride and sulfur) that could not have been the result of contamination. This was followed up by the deployment of the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS) in 2009, which discovered abundant supplies of water around the southern polar region,
However, that which was discovered on the surface paled in comparison the water that was discovered beneath it. Evidence of water in the interior was first revealed by the ISRO’s Chandrayaan-1 lunar orbiter – which carried the NASA’s Moon Mineralogy Mapper (M3) and delivered it to the surface. Analysis of this and other data has showed that water in the Moon’s interior is up to a million times more abundant than what’s on the surface.
The presence of so much water beneath the surface has begged the question, where did it all come from? Whereas water that exists on the Moon’s surface in lunar regolith appears to be the result of interaction with solar wind, this cannot account for the abundant sources deep underground. A previous study suggested that it came from Earth, as the leading theory for the Moon’s formation is that a large Mars-sized body impacted our nascent planet about 4.5 billion years ago, and the resulting debris formed the Moon. The similarity between water isotopes on both bodies seems to support that theory.
Near-infrared image of the Moon’s surface by NASA’s Moon Mineralogy Mapper on the Indian Space Research Organization’s Chandrayaan-1 mission. Credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS
However, according to Dr. David A. Kring, a member of the research team that was led by Jessica Barnes from Open University, this explanation can only account for about a quarter of the water inside the moon. This, apparently, is due to the fact that most of the water would not have survived the processes involved in the formation of the Moon, and keep the same ratio of hydrogen isotopes.
Instead, Kring and his colleagues examined the possibility that water-bearing meteorites delivered water to both (hence the similar isotopes) after the Moon had formed. As Dr. Kring told Universe Today via email:
“The current study utilized analyses of lunar samples that had been collected by the Apollo astronauts, because those samples provide the best measure of the water inside the Moon. We compared those analyses with analyses of meteoritic samples from asteroids and spacecraft analyses of comets.”
By comparing the ratios of hydrogen to deuterium (aka. “heavy hydrogen”) from the Apollo samples and known comets, they determined that a combination of primitive meteorites (carbonaceous chondrite-type) were responsible for the majority of water to be found in the Moon’s interior today. In addition, they concluded that these types of comets played an important role when it comes to the origins of water in the inner Solar System.
Images produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA’s Lunar Reconnaissance Orbiter reveal features at the Moon’s northern and southern poles, as well as the presence of water frost. Credit: NASA/SwRI
For some time, scientists have argued that the abundance of water on Earth may be due in part to impacts from comets, trans-Neptunian objects or water-rich meteoroids. Here too, this was based on the fact that the ratio of the hydrogen isotopes (deuterium and protium) in asteroids like 67P/Churyumov-Gerasimenko revealed a similar percentage of impurities to carbon-rich chondrites that were found in the Earth’s coeans.
But how much of Earth’s water was delivered, how much was produced indigenously, and whether or not the Moon was formed with its water already there, have remained the subject of much scholarly debate. Thank to this latest study, we may now have a better idea of how and when meteorites delivered water to both bodies, thus giving us a better understanding of the origins of water in the inner Solar System.
“Some meteoritic samples of asteroids contain up to 20% water,” said Kring. “That reservoir of material – that is asteroids – are closer to the Earth-Moon system and, logically, have always been a good candidate source for the water in the Earth-Moon system. The current study shows that to be true. That water was apparently delivered 4.5 to 4.3 billion years ago.“
The existence of water on the Moon has always been a source of excitement, particularly to those who hope to see a lunar base established there someday. By knowing the source of that water, we can also come to know more about the history of the Solar System and how it came to be. It will also come in handy when it comes time to search for other sources of water, which will always be a factor when trying to establishing outposts and even colonies throughout the Solar System.
Artist rendering of Orbital ATK concept for an initial lunar habitat outpost, as it would appear with NASA’s Orion spacecraft in 2021. Credit: Orbital ATK
Artist rendering of Orbital ATK concept for an initial lunar habitat outpost, as it would appear with NASA’s Orion spacecraft in 2021. Credit: Orbital ATK
Orbital ATK has unveiled a practical new proposal to build a near term man-tended outpost in lunar orbit that could launch by 2020 and be operational in time for a lunar link-up with NASA’s Orion crew module during its maiden mission, when American astronauts finally return to the Moon’s vicinity in 2021 – thus advancing America’s next giant leap in human exploration of deep space.
The intrepid offer by Orbital could be carried out rather quickly because it utilizes an evolved version of the company’s already proven commercial Cygnus space station resupply freighter as “the building block … in cislunar space,” said Frank DeMauro, Orbital ATK Vice President for Human Spaceflight Systems, in an exclusive interview with Universe Today. See an artist concept in the lead image.
“Our Cygnus spacecraft is the building block to become a vehicle for exploration beyond low Earth orbit,” Orbital ATK’s Frank DeMauro told Universe Today.
“We are all about supporting NASA’s Mission to Mars. We feel that getting experience in cislunar space is critical to the buildup of the capabilities to go to Mars.”
NASA’s agency wide goal is to send astronauts on a ‘Journey to Mars’ in the 2030s – and expeditions to cislunar space in the 2020s serve as the vital ‘proving ground’ to fully develop, test out and validate the robustness of crucial technologies upon which the astronauts lives will depend on later Red Planet missions lasting some 2 to 3 years.
Orbital ATK’s lunar-orbit outpost proposal was announced at an official hearing of the US House of Representatives Subcommittee on Space on Wednesday, May 18, by former NASA Astronaut and Orbital ATK President of the Space Systems Group, Frank Culbertson.
“A lunar-orbit habitat will extend America’s leadership in space to the cislunar domain,” said Orbital ATK President of the Space Systems Group, Frank Culbertson.
“A robust program to build, launch and operate this initial outpost would be built on NASA’s and our international partners’ experience gained in long-duration human space flight on the International Space Station and would make use of the agency’s new Space Launch System (SLS) and Orion deep-space transportation system.”
The idea is to assemble an initial crew-tended habitat with pressurized work and living volume for the astronauts based on a Cygnus derived vehicle, and have it pre-positioned and functioning in lunar-orbit by 2020.
As envisioned by Orbital ATK, the habitat would be visited during NASA’s first manned mission of SLS and Orion to the Moon known as Exploration Mission-2 (EM-2).
The three week long EM-2 lunar test flight could launch as early as August 2021 – if sufficient funding is available.
The goals of EM-2 and following missions could be significantly broadened via docking with a lunar outpost. And Orion mission durations could be extended to 60 days.
NASA hopes to achieve a launch cadence for Orion/SLS of perhaps once per year.
Therefore autonomy and crew tended capability has to be built in to the lunar habitat right from the start – since crew visits would account for only a fraction of its time but enable vastly expanded science and exploration capabilities.
The initial lunar habitat envisioned by Orbital ATK would be comprised of two upgraded Cygnus pressurized vehicles – provisionally dubbed as Exploration Augmentation Modules (EAM). They would be attached to a multi-port docking module very similar in concept and design to the docking Nodes already flying in orbit as integral components of the ISS.
A Cygnus cargo spacecraft named the SS Rick Husband is being prepared inside the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center for upcoming Orbital ATK CRS-6/OA-6 mission to deliver hardware and supplies to the International Space Station. The Cygnus launched atop a United Launch Alliance Atlas V rocket on March 22, 2016. Credit: Ken Kremer/kenkremer.com
The lunar Cygnus vehicles would be upgraded from the enhanced cargo ships currently being manufactured and launched to the ISS.
“There are additional capabilities that we can put into the Cygnus module. We can make them longer and bigger so they can carry more logistics and carry more science,” DeMauro elaborated.
A variety of supplementary subsystems would also need to be enhanced.
“We looked at what systems we would need to modify to make it a long term habitation module. Since we would not be docked to the ISS, we would need our own Environmental Control and Life Support Systems (ECLSS) out at lunar orbit to support the crew.”
“The service module would also need to be improved due to the high radiation environment and the longer time.”
“We also need to look at the thermal protection subsystem, radiation protection subsystem and power subsystems to support the vehicle for many years as opposed to the short time spent at the ISS. More power is also needed to support more science. We also need a propulsion system to get to the Moon and maintain the vehicle.”
“All that work is getting looked at now – to determine what we need to modify and upgrade and how we would do all that work,” DaMauro told me.
The habitat components would be launched to the Moon on a commercial launch vehicle.
High on the list of candidate launchers would be the United Launch Alliance Atlas V rocket which recently already successfully delivered two Cygnus cargo ships to the ISS in Dec. 2015 and March 2016.
Other potential boosters include the ULA Delta IV and even ESA’s Ariane V as a way to potentially include international participation.
Inside the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center in Florida, a Cygnus cargo spacecraft is being prepared for the upcoming Orbital ATK Commercial Resupply Services-6 mission to deliver hardware and supplies to the International Space Station. The Cygnus was named SS Rick Husband in honor of the commander of the STS-107 mission. On that flight, the crew of the space shuttle Columbia was lost during re-entry on Feb. 1, 2003. The Cygnus launched atop a United Launch Alliance Atlas V rocket on March 22. Credit: Ken Kremer/kenkremer.com
The habitat components could be manufactured and launched about three years after getting a ‘Go Ahead’ contract from NASA.
Orbital ATK already has an established production line flowing to manufacture a steady stream of Cygnus cargo freighters to fulfill their NASA commercial resupply contract with NASA for the ISS – accumulating know how and cost reduction efficiencies.
“Since many aspects of operations in deep space are as yet untested, confidence must be developed through repeated flights to, and relatively long-duration missions in, cislunar space,” says Culbertson.
“Orbital ATK continues to operate our Cygnus cargo logistics vehicle as a flagship product, so we are ready to quickly and affordably implement an initial Cygnus-derived habitat in cislunar space within three years of a go-ahead.”
Over time, the outpost could be expanded with additional habitat and research modules delivered by Orion/SLS, commercial or international rockets. Perhaps even Bigelow expandable commercial modules could be added later.
Cygnus is suitable for wide ranging science experiments and gear. It could also launch cubesats – like the current Cygnus berthed at the ISS is equipped with a cubesat deployer.
Potential lunar landers developed by international partners could dock at the cislunar habitats open docking ports in between surface science forays.
“We are doing science now on Cygnus and we would expect to carry along science experiments on the new Cygnus vehicle. The vehicle is very attractive to science experiments,” DeMauro explained.
“There really is no limit to what the outpost could become.”
“What we put out is very exciting,” DeMauro noted.
“As a company we are looking forward to working in this arena. Our suggested plans are in line with where NASA wants to go. And we think we are the right company to play a big part in that!”
By incorporating commercial companies and leveraging the considerable technology development lessons learned from Cygnus, NASA should realize significant cost savings in implementing its human exploration strategy. Although Orbital ATK is not divulging a cost estimate for the lunar habitat at this time, the cost savings from a commercial partner should be considerable. And the 3 year time frame to launch is very attractive.
Orion is designed to send astronauts deeper into space than ever before, including missions to the Moon, asteroids and the Red Planet. Cygnus derived modules and/or other augmenting hardware components will be required to carry out any round trip human missions to the Martian surface.
NASA is now building the next Orion capsule at the Kennedy Space Center. It will launch unpiloted atop the first SLS rocket in late 2018 on the EM-1 mission.
Lockheed Martin engineers and technicians prepare the Orion pressure vessel for a series of tests inside the proof pressure cell in the Neil Armstrong Operations and Checkout Building at NASA’s Kennedy Space Center in Florida. Photo credit: NASA/Kim Shiflett
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com
Lockheed Martin engineers and technicians prepare the Orion pressure vessel for a series of tests inside the proof pressure cell in the Neil Armstrong Operations and Checkout Building at NASA's Kennedy Space Center in Florida. Photo credit: NASA/Kim Shiflett
Lockheed Martin engineers and technicians prepare the Orion pressure vessel for a series of tests inside the proof pressure cell in the Neil Armstrong Operations and Checkout Building at NASA’s Kennedy Space Center in Florida. Photo credit: NASA/Kim Shiflett
The next Orion crew module in line to launch to space on NASA’s Exploration Mission-1 (EM-1) has passed a critical series of proof pressure tests which confirm the effectiveness of the welds holding the spacecraft structure together.
Any leaks occurring in flight could threaten the astronauts lives.
Engineers and technicians conducted the pressure tests on the Orion EM-1 pressure vessel, which was welded together at NASA’s Michoud Assembly Facility in New Orleans and then shipped to NASA’s Kennedy Space Center in Florida just 3 months ago.
The pressure vessel is the structural backbone for the vehicles that will launch American astronauts to deep space destinations.
“This is the first mission where the Orion spacecraft will be integrated with the large Space Launch System rocket. Orion is the vehicle that’s going to take astronauts to deep space,” NASA Orion program manager Scott Wilson told Universe Today.
“The tests confirmed that the weld points of the underlying structure will contain and protect astronauts during the launch, in-space, re-entry and landing phases on the Exploration Mission 1 (EM-1), when the spacecraft performs its first uncrewed test flight atop the Space Launch System rocket,” according to a NASA statement.
After flying to KSC on Feb 1, 2016 inside NASA’s unique Super Guppy aircraft, this “new and improved” Orion EM-1 pressure vessel was moved to the Neil Armstrong Operations and Checkout (O&C) Building for final assembly by prime contractor Lockheed Martin into a flight worthy vehicle.
Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com
Since then, technicians have worked to meticulously attach hundreds of strain gauges to the interior and exterior surfaces of the vehicle to prepare for the pressure tests.
The strain gauges provide real time data to the analysts monitoring the changes during the pressurization.
Orion was moved to a test stand inside the proof pressure cell high bay and locked inside behind large doors.
Lockheed Martin engineers then incrementally increased the pressure in the proof testing cell in a series of steps over two days. They carefully monitored the results along the way and how the spacecraft reacted to the stresses induced by the pressure increases.
The maximum pressure reached was 1.25 times normal atmospheric pressure – which exceeds the maximum pressure it is expected to encounter on orbit.
“We are very pleased with the performance of the spacecraft during proof pressure testing,” said Scott Wilson, NASA manager of production operations for the Orion Program.
“The successful completion of this test represents another major step forward in our march toward completing the EM-1 spacecraft, and ultimately, our crewed missions to deep space.”
Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com
With the pressure testing satisfactorily completed, technicians will move Orion back to birdcage assembly stand for the “intricate work of attaching hundreds of brackets to the vessel’s exterior to hold the tubing for the vehicle’s hydraulics and other systems.”
To prepare for launch in 2018, engineers and technicians from NASA and prime contractor Lockheed Martin will spend the next two years meticulously installing all the systems amounting to over 100,000 components and gear required for flight.
This particular ‘Lunar Orion’ crew module is intended for blastoff to the Moon in 2018 on NASA’s Exploration Mission-1 (EM-1) atop the agency’s mammoth new Space Launch System (SLS) rocket, simultaneously under development. The pressurized crew module serves as the living quarters for the astronauts comprising up to four crew members.
NASA’s Space Launch System (SLS) blasts off from launch pad 39B at the Kennedy Space Center in this artist rendering showing a view of the liftoff of the Block 1 70-metric-ton (77-ton) crew vehicle configuration. Credit: NASA/MSFC
EM-1 itself is a ‘proving ground’ mission that will fly an unmanned Orion thousands of miles beyond the Moon, further than any human capable vehicle, and back to Earth, over the course of a three-week mission.
The 2018 launch of NASA’s Orion on the unpiloted EM-1 mission counts as the first joint flight of SLS and Orion, and the first flight of a human rated spacecraft to deep space since the Apollo Moon landing era ended more than 4 decades ago.
Orion is designed to send astronauts deeper into space than ever before, including missions to the Moon, asteroids and the Red Planet.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
NASA’s Orion EM-1 crew module pressure vessel arrived at the Kennedy Space Center’s Shuttle Landing Facility tucked inside NASA’s Super Guppy aircraft on Feb 1, 2016. The Super Guppy opens its hinged nose to unload cargo. Credit: Ken Kremer/kenkremer.com
A filtered 'Blue Moon' from July 31st, 2015. Image credit and copyright: John Chumack
Brace yourselves. You are about to hear talk this week of an astronomical non-occurrence of the utmost in obscurity. We’re talking about this weekend’s Blue Moon.
Now, I know what you’re thinking. Isn’t a ‘Blue Moon’ the second Full Moon of the month? How can a Blue Moon fall on the 21st? Trust me, we’re both correct… in a sense. The term ‘Blue Moon’ has taken on several meanings over the last few decades, with the ‘the second Full Moon in a calendar month containing two Full Moons’ now in vogue across ye old Internet. It seems the masses just can’t get enough of Super, Blood, Honey and Moons Black and Blue. We point to last month’s rumored ‘Green Moon‘ as evidence. (Spoiler alert: it wasn’t).
No, we’re talking instead of a Blue Moon in an old-timey sense. You’ll be hard pressed to explain source of this week’s Blue Moon for sure, though it has a fascinating origin story.
A Full Moon rising with Saturn and Mars on the night of May 21st, 2016. Image credit: Starry Night Education software.
The term seems to come down to us from the Maine Farmer’s Almanac, which denoted the ‘third Full Moon in an astronomical season with four as blue.’ The lunar synodic period of 29.5 days — the length of time it takes the Moon to return to a like phase, such as New to New, or Full to Full — means that on most years, there are 12 Full Moons. 29.5 times 12 comes out about 11 days short of a 365.25 day solar year at 354 days, meaning that about every three years, we have a year with 13 Full Moons.
Not a big deal, you say? Well, it assures that lunar based forms of reckoning time, such as the Muslim calendar loses 11 days relative to the Gregorian calendar every year.
March Equinox- March 20th 4:30 Universal Time (UT)
March Full Moon- March 23rd 12:02 UT
April Full Moon- April 22nd 5:22 UT
May Full Moon- May 21st 21:17 UT (3rd in an astronomical season, ‘blue’)
June Full Moon- June 20th 11:05 UT
June Solstice- June 20th 22:34 UT
The last time we had a season with four Full Moons was August 21st, 2013, and the next Blue Moon under this rule is May 18th, 2019.
Adding a pinch of blue to the Full Moon with a military flashlight filter. Image credit: Dave Dickinson
Of course, a deeper riddle is just why the Maine Farmer’s Almanac termed this occurrence as Blue, and why they picked the 3rd of a season with 4 specifically… one legend goes that the extra anomalous Full Moon was depicted on the calendar in blue ink to stand out. We’d love to get our hands on a copy of the Old Maine Farmer’s Almanac circa late 19th early 20th century era to see if this was indeed the case. This is on our list of research projects, next time we find ourselves back in our home state of Maine.
We’ve chronicled the tales of Moons, both Black and Blue. Sky and Telescope also explored the role they had in introducing the modern day Blue Moon into common vernacular. We’ll admit, the ‘2nd in a month with two Full Moons’ is a much easier rule to explain!
Of course, the Moon isn’t scheduled to actually appear blue this week… that’s actually a much rarer occurrence, and the Moon doesn’t need to even be Full for this to happen. In September 23rd, 1950, the residents of the northeastern United States saw the 94% illuminated waxing gibbous Moon rise with a distinctly bluish cast, owing to the high concentration of oily soot particles suspended high in the atmosphere, scattering out red and yellow light but filtering through blue. Reports of similar Blue Moons dot observational lore, though to our knowledge, no one has actually captured an image of such a cerulean apparition of the Moon.
The rising Full Moon of September 23rd, 1950. Image credit: Stellarium
Is the Moon ever really Full? You can make a pretty good argument that the Moon as seen from the Earth is never truly fully illuminated, though it gets really close. Full 100% illumination would occur when the Moon is exactly opposite to the Sun, but when this occurs, the Moon also passes into the dark shadow of the Earth, during a total lunar eclipse.
Fun fact: the next ‘Blue Blood Moon’ lunar eclipse occurs on January 31st, 2018, following the ‘2nd Full Moon in a month with 2′ rule.
I see some blue in there… the Full Moon, enhanced to bring out subtle color. Image credit and copyright: Rolf Wahl Olsen
The May Full Moon also has the romantic name of the Full Flower, Corn Planting or Milk Moon in Algonquin Indian lore.
In 2016, the Moon continues to follow a shallow path relative to the ecliptic plane, which in turn traces out the Earth’s path around the Sun. 2015 was the bottoming out of the ‘shallow year’ known as a minor lunar standstill, and we’re now headed towards a hilly or steep year of a major lunar standstill in 2025, a time once every 19 years when the Moon rides high in the sky, adding its 5 degree inclination relative to the ecliptic plane.
Too bad Mars doesn’t have a large moon… because it would indeed appear blue, as do Martian sunsets. Image credit: JPL/NASA
Will this weekend’s olden times Blue Moon gain traction in today’s fast-paced social media news cycle? Stay tuned!
