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!
The March 5th 2015 Mini-Moon. Image credit and copyright: Alan Dyer
Do you welcome the extra evening light of the Full Moon, or curse the additional light pollution? Either way, this week’s Full Moon on Friday April 22nd is special. It’s the smallest Full Moon of 2016, something we here at Universe Today have christened the Mini-Moon.
Mini-Moon 2016: This year’s Mini-Moon falls on April 22nd at 5:25 Universal Time (UT), just 13 hours and 19 minutes after lunar apogee the evening prior at 16:06 UT on April 21st. Though apogee on the 21st is 406,350 km distant – a bit on the far end, but the third most distant for the year by 300 km — this week’s Full Moon is the closest to apogee for 2016 time-wise. The 2015 Mini-Moon was even closer, in the 10 hour range, but you’ll have to wait until December 10th, 2030 to find a closer occurance.
The Mini-Moon versus the 2011 Supermoon. Image credit and copyright: Ken Lord.
What is the Mini-Moon, you might ask? As with the often poorly defined Supermoon, we like to eschew the ambiguous ‘90% of its orbit’ definition, and simply refer to it as a Full Moon occurring within 24 hours of lunar apogee, or its farthest point from the Earth in its orbit.
Fun fact: the 29.55 day period from perigee to perigee (or lunar apogee-to-apogee) is known as an anomalistic month.
Mini-Moons by year for the remainder of the decade. Note that the 2020 Full Moon is also the 2nd of the month… A ‘Mini-Blue Halloween Moon?’ Image credit: Dave Dickinson
Thank our Moon’s wacky orbit for all this lunacy. Inclined 5.14 degrees relative to the ecliptic plane, the Moon returns to the same phase (say, Full back to Full) every 29.53 days, known as a synodic month. The Moon can appear 33.5′ across during perigee, and shrink to 29.4′ across near apogee.
The appearance of the Moon through one synodic period. Note that in addition to rocking back and forth (libration) and side-to-side (nutation), the Moon appears to swell and shrink in size. Wikimedia Commons graphic in the Public Domain.
And don’t fear the ‘Green Moon,’ and rumors going ’round ye’ ole internet that promise a jaded Moon will occur in April or May; this is 100% non-reality based, seeking to join the legends of Super, Blood, and Full Moons, Black and Blue.
No. Just. No. Image faked by: David Dickinson.
The April Full Moon is also known as the Full Pink Moon to the Algonquin Indians. The April Full Moon, can, on occasion be the Full Moon ushering in Easter (known as the Paschal Moon) as per the rule established by the 325 AD council of Nicaea, stating Easter falls on the first Sunday after the first Full Moon after the fixed date of the Vernal Equinox of March 21st. Easter can therefore fall as late as April 25th, as next occurs on 2038. The future calculation of Easter by the Church gets the Latin supervillain-sounding name of Computus.
Looking east on the evening of April 21st. Image credit: Stellarium
Of course, the astronomical vernal equinox doesn’t always fall on March 21st, and to complicate matters even further, the Eastern Orthodox Church uses the older Julian Calendar and therefore, Easter doesn’t always align with the modern western Gregorian calendar used by the Roman Catholic Church.
The Moon can create further complications in modern timekeeping as well.
Here’s one wonderful example we recently learned of in our current travels. The Islamic calendar is exclusively based on the synodic cycle of the Moon, and loses 11 days a year in relation to the Gregorian solar calendar. Now, Morocco officially adopted Daylight Saving (or Summer) Time in 2007, opting to make the spring forward during the last weekend of March, as does the European Union to the north. However, the country reverts back to standard time during the month of Ramadan… otherwise, the break in the daily fast during summer months would fall towards local midnight.
You can see a curious future situation developing. In 2016, Ramadan runs from sundown June 5th, to July 4th. Each cycle begins with the sighting of the thin waxing crescent Moon. However, as Ramadan falls earlier, you’ll get a bizarre scenario such as 2022, when Morocco springs forward on March 27th, only to fall back to standard time six days later on April 2nd on the start of Ramadan, only to jump forward again one lunation later on April 30th!
Morocco is the only country we’ve come across in our travels that follows such a convoluted convention of timekeeping.
And the Spring Mini-Moon sets us up for Supermoon season six months later this coming October-November-December. Though lunar perigees less than 24 hours from Full usually occur as a trio, an apogee less than 24 hours from Full is nearly always a solitary affair, owing to the slightly slower motion of the Moon at a farther distance.
Don’t miss the shrunken Mini-Moon rising on the evenings of Thursday April 21st and Friday 22nd, coming to a sky near you.
We always see the same side of the Moon. It’s always up there, staring down at us with its terrifying visage. Or maybe it’s a creepy rabbit? Anyway, it’s always showing us the same face, and never any other part.
This is because the Moon is tidally locked to the Earth; the same fate that affects every single large moon orbiting a planet. The Moon is locked to the Earth, the Jovian moons are locked to Jupiter, Titan is locked to Saturn, etc.
As the Moon orbits the Earth, it slowly rotates to keep the same hemisphere facing us. Its day is as long as its year. And standing on the surface of the Moon, you’d see the Earth in roughly the same spot in the sky. Forever and ever.
Because of tidal locking, you’d see Earth in roughly the same spot from the Moon forever. For-eh-ver. For-EH-VER. Credit: NASA / Goddard / Arizona State University
We see this all across the Solar System.
But there’s one place where this tidal locking goes to the next level: the dwarf planet Pluto and its large moon Charon are tidally locked to each other. In other words, the same hemisphere of Pluto always faces Charon and vice versa.
It take Pluto about 6 and a half days for the Sun to return to the same point in the sky, which is the same time it takes Charon to complete an orbit, which is the same time it takes the Sun to pass through the sky on Charon.
Since Pluto eventually locked to its moon, can the same thing happen here on Earth. Will we eventually lock with the Moon?
Before we answer this question, let’s explain what’s going on here. Although the Earth and the Moon are spheres, they actually have a little variation. The gravity pulling on each world creates love handle tidal bulges on each world.
And these bulges act like a brake, slowing down the rotation of the world. Because the Earth has 81 times the mass of the Moon, it was the dominant force in this interaction.
In the early Solar System, both the Earth and the Moon rotated independently. But the Earth’s gravity grabbed onto those love handles and slowed down the rotation of the Moon. To compensate for the loss of momentum in the system, the Moon drifted away from the Earth to its current position, about 370,000 kilometers away.
But Moon has the same impact on the Earth. The same tidal forces that cause the tides on Earth are slowing down the Earth’s rotation bit by bit. And the Moon is continuing to drift away a few centimeters a year to compensate.
It’s hard to estimate exactly when, but over the course of tens of billions of years, the Earth will become locked to the Moon, just like Pluto and Charon.
Pluto and Charon are tidally locked to each other. Credit: NASA / JHUAPL / SwRI
Of course, this will be long after the Sun has died as a red giant. And there’s no way to know what kind of mayhem that’ll cause to the Earth-Moon system. Other planets in the Solar System may shift around, and maybe even eject the Earth into space, taking the Moon with it.
What about the Sun? Is it possible for the Earth to eventually lock gravitationally to the Sun?
Astronomers have found extrasolar planets orbiting other stars which are tidally locked. But they’re extremely close, well within the orbit of Mercury.
Here in our Solar System, we’re just too far away from the Sun for the Earth to lock to it. The gravitational influence of the other planets like Venus, Mars and Jupiter perturb our orbit and keep us from ever locking. Without any other planets in the Solar System, though, and with a Sun that would last forever, it would be an inevitability.
It is theoretically possible that the Earth will tidally lock to the Moon in about 50 billion years or so. Assuming the Earth and Moon weren’t consumed during the Sun’s red giant phase. I guess we’ll have to wait and see.
The Moon occults Aldebaran last lunation on March 14th as seen from India. Image credit and copyright: Rajneesh Parashar
So, did you miss yesterday’s occultation of Venus by the Moon? It was a tough one, to be sure, as the footpath for the event crossed Europe and Asia in the daytime. Watch that Moon, though, as it crosses back into the evening sky later this week, and occults (passes in front of) the bright star Aldebaran for eastern North America and, for Hawaii-based observers, actually covers the brightest of the asteroids, 4 Vesta. Continue reading “Watch the Moon Occult Vesta and Aldebaran This Weekend”
Do you see it? I 2% illuminated waning 'Old Moon,' 24+ hours from New. The April 6th Moon will be about as thin. Image credit: Dave Dickinson
Sometimes, the Universe seems bent on hiding the most glorious of events right in plain sight. Just a such an event occurs next week, when the slender waning crescent Moon occults the planet Venus for observers across Europe, the United Kingdom and northern Asia. Continue reading “A Challenging Daytime Occultation of Venus for Europe”
A six degree True Polar Wander occurred on the Moon due to ancient volcanic activity. Image: University of Arizona/James Tuttle Keane
It’s tempting to think that the Moon never changes. You can spend your whole life looking at it, and see no evidence of change whatsoever. In fact, the ancients thought the whole Universe was unchanging.
You may have heard of a man named Aristotle. He thought the Universe was eternal and unchanging. Obviously, with our knowledge of the Big Bang, stellar evolution, and planetary formation, we know better. Still, the placid and unchanging face of the Moon can tempt us into thinking astronomers are making up all this evolving universe stuff.
But now, according to a new paper in Nature, the Moon’s axis of rotation is different now than it was billions of years ago. Not only that, but volcanoes may been responsible for it. Volcanoes! On our placid little Moon.
The clue to this lunar True Polar Wander (TPW) is in the water ice locked in the shadows of craters on the Moon. When hydrogen was discovered on the surface of the Moon in the 1990s by the Lunar Prospector probe, scientists suspected that they would eventually find water ice. Subsequent missions proved the presence of water ice, especially in craters near the polar regions. But the distribution of that water-ice wasn’t uniform.
You would expect to see ice uniformly distributed in the shadows of craters in the polar regions, but that’s not what scientists have found. Instead, some craters had no evidence of ice at all, which led the team behind this paper to conclude that these ice-free craters must have been exposed to the Sun at some point. What else would explain it?
The way that the ice in these craters is distributed forms two trails that lead away from each pole. They’re mirror images of each other, but they don’t conform with the Moon’s current axis of rotation, which is what led the team to conclude that the Moon underwent a 6 degree TPW billions of years ago.
The paper also highlights the age of the water on the Moon. Since the TPW, and the melting of some of the ice as a result of it, occurred some billions of years ago, then the water ice that is still frozen in the shadows of some of the Moon’s craters must be ancient. According to the paper, its existence records the “early delivery of water to the inner Solar System.” Hopefully, a future mission will return a sample of this ancient water for detailed study.
But even more interesting than the age of the ice in the craters and the TPW, to me anyways, is what is purported to have caused it. The team behind the paper reports that volcanic activity on the Moon in the Procellarum region, which was most active in the early history of the Moon, moved a substantial amount of material and “altered the density structure of the Moon.” This alteration would have changed the moments of inertia on the Moon, resulting in a TPW.
It’s strange to think of the Moon with volcanic activity viewable from Earth. I wonder what effect visible lunar volcanoes would have had on thinkers like Aristotle, if lunar volcanic activity had occurred during recorded history, rather than ending one billion years ago or so.
We know that events like eclipses and comets caused great confusion and sometimes upheaval in ancient civilizations. Would lunar volcanoes have had the same effect?
