The gibbous moon shines on Sept. 5, 2014. Credit: Christian Kamber
While the SuperMoon of earlier this week got a lot of attention — and rightly so, given the Moon was closest in its orbit to Earth when it was full — the waning and waxing phases around our celestial neighbor are also beautiful. Haunting, in fact.
These shots were taken by members of our Universe Today Flickr pool, with the moon either entering or exiting the full moon phase. Got some stunning astronomy shots to share? Feel free to add your contributions to the group (which says you will give us permission to publish) and we may include them in a future story.
The moon in its waning gibbous phase on Sept. 12, 2014. Photo taken with a Canon 700D attached to a Maksutov 127mm telescope. Credit: Sarah&Simon FisherThe moon shines red in this photo taken from Newcastle upon Tyne, England on Sept. 11, 2014. Credit: David BlanchflowerThe large craters Atlas (left) and Hercules (below) on the moon. Taken using a Canon 1100D. Credit: Paul M. Hutchinson
EDIT: We just received a nice sequence of shots from Laura Austin:
A busy hermit spider spinning its web at dusk, pictured here in front of the not-quite-full Moon on September 7, 2014. This is a composite of two images, one focused on the spider and the other on the Moon. Credit and copyright: Brian who is called Brian on Flickr.
Up in the sky — it’s a bird, it’s a plane… no, it’s a spider and a SuperMoon! Well, not quite. This composite image by Brian who is called Brian on Flickr was actually taken last night, on September 7, 2014, but it’s an awesome lead-in for our usual request for astrophotos of the Harvest Full — and super — Moon tonight.
So, post your images on our Flickr page, tag your photo with #supermoonphoto to get our attention on social media. We’ll include many in our article here, retweet them, and generally promote them anywhere and everywhere we can think of.
Of course, the future has already happened in Australia, and you can see the full Moon setting in Australia, below, as well as Moonrise images just coming in from Europe:
The big Harvest Moon sinks into the West, as seen from New South Wales, Australia on September 9, 2014. Credit and copyright: Wes Schulstad/Alien Shores.
And just how big is the Moon? Astrophotographer Göran Strand (@Astrofotografen) posted this on Twitter:
A single shot image of the 3rd and last ‘super’ Moon of the year taken from Lahore, Pakistan on September 8, 2014 just 20 minutes after sunset. Credit and copyright: Roshaan Bukhari. Taken with a Meade 70mm refractor and HTC one x phone.A lovely pale pink moonrise of the Harvest Moon on September 8, 2014. Credit and copyright: DawnSunrise. Moonset on the morning of September 8, 2014, as the Moon is just dropping below the Horizon. Credit and copyright: Sculptor Lil on Flickr.
UPDATE: More new images:
The full Harvest Moon as seen from rural Georgia, northwest of Atlanta. Taken with a telescope and a smart phone. Credit and copyright: Connor Lewis.Super Harvest Moon, September 8, 2014. Photo HDR and magnification of the Moon for a “Super Moon” effect. Credit and copyright: VegaStarCarpentier Photography.Supermoon through the clouds on September 9, 2014. Credit and copyright: scul-001 on Flickr.Super Luna on September 8,, 2014. Credit and copyright: Héctor Barrios.Full Harvest Moon on September 8, 2014. Credit and copyright: Harbor City Media/Steve Fitzmaurice.Full Moon setting on September 9, 2014 in the UK. Credit and copyright: Sculptor Lil.
Last month's supermoon within 24 hours of perigee. Credit: Blobrana
Time to dust off those ‘what is a perigee Full Moon’ explainer posts… the supermoon once again cometh this weekend to a sky near you.
Yes. One. More. Time.
We’ve written many, many times — as have many astronomy writers — about the meme that just won’t die. The supermoon really brings ‘em out, just like werewolves of yore… some will groan, some will bemoan the use of a modernized term inserted into the common astronomical vernacular that was wrought by an astrologer, while others will exclaim that this will indeed be the largest Full Moon EVER…
But hey, it’s a great chance to explain the weird and wonderful motion of our nearest natural neighbor in space. Thanks to the Moon, those astronomers of yore had some great lessons in celestial mechanics 101. Without the Moon, it would’ve been much tougher to unravel the rules of gravity that we take for granted when we fling a probe spaceward.
The Moon reaches Full on Tuesday, September 9th at 1:38 Universal Time (UT), which is 9:38 PM EDT on the evening of the 8th. The Moon reaches perigee at less than 24 hours prior on September 8th at 3:30 UT — 22 hours and 8 minutes earlier, to be precise — at a distance 358,387 kilometres distant. This is less than 2,000 kilometres from the closest perigee than can occur, and 1,491 kilometres farther away than last month’s closest perigee of the year, which occurred 27 minutes prior to Full Moon.
A Proxigean or Perigee Full “Supermoon” as reckoned by our preferred handy definition of “a Full Moon occurring within 24 hours of perigee” generally occurs annually in a cycle of three over two lunar synodic periods, and moves slowly forward by just shy of a month through the Gregorian calendar per year. The next cycle of “supermoons” starts on August 30th, 2015, and you can see our entire list of cycles out through 2020 here.
What’s the upshot of all this? Well, aside from cluttering inboxes and social media with tales of the impending supermoon this weekend, the rising Moon will appear 33.5’ arc minutes in diameter as opposed to its usually quoted average of 30’ in size. And remember, that’s in apparent size as seen from our Earthly vantage point… can you spy a difference from one Full Moon to the next? Fun fact: the rising Moon is actually farther away from you to the tune of about one Earth radius than when it’s directly overhead at the zenith.
Fed up with supermoon-mania? The September Full Moon also has a more pedestrian name: The Harvest Moon. Actually, this is the Full Moon that falls nearest to the September Equinox, marking the start of the astronomical season of Fall in the northern hemisphere and Spring in the southern. In the current first half of the 21st century, the September Equinox falls on the 22nd or 23rd, meaning that the closest Full Moon (and thus the Harvest Moon) can sometimes fall in October, as last happened in 2009 and will occur again in 2017. In this instance, the September Full Moon would then be referred to as the Corn Moon as reckoned by the Algonquins, and is occasionally referred to as the Drying Grass Moon by Sioux tribes. In 2014, the Harvest Full Moon “misses” falling in October by about 32 hours!
The waning gibbous Moon of July 14th, 2014- shortly after the first supermoon of the year. Credit: Blobrana.
So, why is it known as the Harvest Moon? Well, in the age before artificial lighting (and artificial light pollution) the rising of the Full Moon as the Sun sets allowed for a few hours of extra illumination to bring in crops. In October, the same phenomenon gave hunters a few extra hours to track game by the light of the Full Hunters Moon, both essential survival activities before the onset of the long winter.
And that Full Harvest Moon seems to “stick around” on successive evenings. This is due to the relatively shallow angle of the evening ecliptic to the eastern horizon as seen from mid-northern latitudes in September.
The rising Full Moon on the evening of September 8th as seen from latitude 40 degrees north. Note the shallow angle of the ecliptic. Created using Stellarium.
Here’s a sample of rising times for the Moon this month as seen from Baltimore, Maryland at 39.3 degrees north latitude:
Saturday, September 6th: 5:43 PM EDT
Sunday, September 7th: 6:23 PM EDT
Monday, September 8th: 7:05 PM EDT
Tuesday, September 9th: 7:44 PM EDT
Wednesday, September 10th: 8:22 PM EDT
Note the Moon rises only ~40 minutes later on each successive evening.
The Full Harvest Moon of 2013 plus aircraft. Credit: Stephen Rahn.
We’re also headed towards a “shallow year” in 2015, as the Moon bottoms out relative to the ecliptic and only ventures 18 degrees 20’ north and south of the celestial equator at shallow minimum. This is due to what’s known as the Precession of the Line of Apsides as the gravitational pull of the Sun slowly drags the orbit of the Moon round the earth once every 8.85 years. The nodes where the ecliptic and path of the Moon meet — and solar and lunar eclipses occur — also move slowly in an opposite direction of the Moon’s motion, taking just over twice as long as the Precession of the Line of Apsides to complete one revolution around the ecliptic at 18.6 years. This is one of the more bizarre facts about the motion of the Moon: its orbital tilt of 5.1 degrees is actually fixed with respect to the ecliptic as traced out by the Earth’s orbit about the Sun, not our rotational axis. Native American and ancient Northern European knew of this, and the next “Long Night’s Moon” also called a “Lunar Standstill” when the Moon rides high in the northern hemisphere sky is due through 2024-2025.
The footprint of the September 11th occultation of Uranus. Credit: Occult 4.0.
And to top it off, the Moon occults Uranus just two days after Full on September 11th as seen from northeastern North America, Greenland, Iceland and northern Scandinavia. We’re in a cycle of occultations of Uranus by the Moon from late 2014 through 2015, and this will set the ice giant up for a spectacular close pass, and a rare occultation of the planet for a remote region in the Arctic during the October 8th total lunar eclipse…
The last dawn pairing of Venus, Jupiter and the crescent Moon in the dawn sky in 2012... this month's will be much tighter! Credit: Tavi Greiner.
“What are those two bright stars in the morning sky?”
About once a year we can be assured that we’ll start fielding inquires to this effect, as the third and fourth brightest natural objects in the sky once again meet up.
We’re talking about a conjunction of the planets Jupiter and Venus. Venus has been dominating the dawn sky for 2014, and Jupiter is fresh off of solar conjunction on the far side of the Sun on July 24th and is currently racing up to greet it.
We just caught sight of Jupiter for the first time for this apparition yesterday from our campsite on F.E. Warren Air Force Base in Cheyenne, Wyoming. We’d just wrapped up an early vigil for Perseid meteors and scrambled to shoot a quick sequence of the supermoon setting behind a distant wind farm. Jupiter was an easy catch, first with binoculars, and then the naked eye, using brilliant Venus as a guide post.
The view looking eastward at dawn on August 18th, including a five degree telrad (red circles) and a one degree telescopic field of view (inset). Created using Stellarium.
And Jupiter will become more prominent as the week progresses, climaxing with a fine conjunction of the pair on Monday, August 18th. This will be the closest planet versus planet conjunction for 2014. At their closest — around 4:00 Universal Time or midnight Eastern Daylight Saving Time — Venus and Jupiter will stand only 11.9’ apart, less than half the diameter of a Full Moon. This will make the pair an “easy squeeze” into the same telescopic field of view at low power. Venus will shine at magnitude -3.9, while Jupiter is currently about 2 magnitudes or 6.3 times fainter at magnitude -1.8. In fact, Jupiter shines about as bright as another famous star just emerging into the dawn sky, Sirius. Such a dawn sighting is known as a heliacal rising, and the first recovery of Sirius in the dawn heralded the flooding of the Nile for the ancient Egyptians and the start what we now term the Dog Days of Summer.
To the naked eye, enormous Jupiter will appear to be the “moon” that Venus never had next weekend. The spurious and legendary Neith reported by astronomers of yore lives! You can imagine the view of the Earth and our large Moon as a would-be Venusian astronomer stares back at us (you’d have to get up above those sulfuric acid clouds, of course!)
Said conjunction is only a product of our Earthly vantage point. Venus currently exhibits a waxing gibbous disk 10” across — three times smaller than Jupiter — but Venus is also four times closer to Earth at 1.61 astronomical units distant. And from Jupiter’s vantage point, you’d see a splendid conjunction of Venus and the Earth, albeit only three degrees from the Sun:
Earth meets Venus, as seen from Jupiter on August 18th. Note the Moon nearby. Created using Starry Night Education Software.
How often do the two brightest planets in the sky meet up? Well, Jupiter reaches the same solar longitude (say, returns back to opposition again) about once every 13 months. Venus, however, never strays more than 47.1 degrees elongation from the Sun and can thus always be found in either the dawn or dusk sky. This means that Jupiter pairs up with Venus roughly about once a year:
A list of Venus and Jupiter conjunctions, including angular separation and elongations (west=dawn, east=dusk) from now until 2020. Created by author.
Note that next year and 2019 offer up two pairings of Jupiter and Venus, while 2018 lacks even one. And the conjunction on August 27th, 2016 is only 4’ apart! And yes, Venus can indeed occult Jupiter, although that hasn’t happened since 1818 and won’t be seen again from Earth until – mark your calendars – November 22nd, 2065, though only a scant eight degrees from the Sun. Hey, maybe SOHO’s solar observing successor will be on duty by then…
Venus has been the culprit in many UFO sightings, as pilots have been known to chase after it and air traffic controllers have made furtive attempts to hail it over the years. And astronomy can indeed save lives when it comes to conjunctions: in fact, last year’s close pairing of Jupiter and Venus in the dusk sky nearly sparked an international incident, when Indian Army sentries along the Himalayan border with China mistook the pair for Chinese spy drones. Luckily, Indian astronomers identified the conjunction before shots were exchanged!
Earth strikes back… firing a 5mw green laser at the 2013 conjunction of Jupiter and Venus. Photo by author.
Next week’s conjunction also occurs against the backdrop of Messier 44/Praesepe, also known as the “Beehive cluster”. It’ll be difficult to catch sight of M44, however, because the entire “tri-conjunction” sits only 18 degrees from the Sun in the dawn sky. Binocs or a low power field of view might tease out the distant cluster from behind the planetary pair.
And to top it off, the waning crescent Moon joins the group on the mornings of August 23rd and 24th, passing about five degrees distant. Photo op! Can you follow Venus up into the daytime sky, using the Moon as a guide? How about Jupiter? Be sure to block that blinding Sun behind a hill or building while making this attempt.
The Moon photobombs the conjunction of Venus and Jupiter on the weekend of August 23rd. Credit: Stellarium.
The addition of the Moon will provide the opportunity to catch a skewed “emoticon” conjunction. A rare smiley face “:)” conjunction occurred in 2009, and another tight skewed tri-conjunction is in the offering for 2056. While many national flags incorporate examples of close pairings of Venus and the crescent Moon, we feel at least one should include a “smiley face” conjunction, if for no other reason than to highlight the irony of the cosmos.
A challenge: can you catch a time exposure of the International Space Station passing Venus and Jupiter? You might at least pull off a “:/” emoticon image!
Don’t miss the astronomical action unfolding in a dawn sky near you over the coming weeks. And be sure to spread the word: astronomical knowledge may just well avert a global catastrophe. The fate of the free world lies in the hands of amateur astronomers!
The supermoon of August 10, 2014 rising behind Mt. Rundle and Banff, Alberta, Canada as shot from the Mt. Norquay viewpoint looking south over the valley. Credit and copyright: Alan Dyer.
Wow! The astrophotographers out there are getting artsy! Take a look at some of the most artistic images of the full Moon we’ve seen yet.
The August 10 full Moon was a so-called “super” Moon — and it was the “super-est” of a trio of full Moons being at perigee, or its closest approach to the Earth in its orbit. It was just 356,896 kilometers distant at 17:44 UTC, less than an hour from Full. You can see a comparison shot of the perigee and apogee Moons this year immediately below. Find all the technical details here, but enjoy a gallery of great images from around the world
A comparison the between two ‘extreme’ full Moons of 2014: the perigee Full Moon of August 10th, and the apogee full Moon of January 16. As seen from Central Italy. Credit and copyright: Giuseppe Petricca.The August 10, 2014 ‘super’ Moon. Credit and copyright: Robbie Ambrose.Supermoon timelapse composite on August 10 near the ship mast at Barnegat Light on Long Beach Island, New Jersey. Credit and copyright: FrankM301 on Flickr.
A cloudy look at the perigee Moon of August 10, 2014 along side the Desde el Obelisco, Malecón de Santo Domingo, Dominican Republic. Credit and copyright: Goku Abreu. ‘Super’ Moon, August 10, 2014, taken with Nikon D80 from Ottawa, Canada. Credit and copyright: Andrew Symes.
Super Moon (and a companion) rising over Brixton, South London. 10/08/2014. Credit and copyright: Owen Llewellyn. Camaro and Full Moon – Aug 9, 2014.Taken from the Cairns Wharf in Australia at dusk using an iPhone 5. Three frames; two exposures each. Credit and copyright: Joseph Brimacombe.
It was prom night in Cairns… so the fancy cars were out. See Joseph’s other “prom supermoon” image here.
People watch the nearly ‘super’ Moon rise on August 9, 2014 near a lighthouse. Credit and copyright: Will Nourse.Perigee Full Moon mosaic from August 10, 2014 (a first attempt at a mosaic!) Credit and copyright: Mary Spicer.Perigee Moon rise over London on August 10, 2014. Credit and copyright: Sculptor Lil.The perigee Moon from Toronto, Canada at 8:35 pm EDT. Credit and copyright: Rick Ellis.A full Moon flyby, as seen from Paris, France. Credit and copyright: Sebastien Lebrigand.
Even NASA got into the “super Moon” astrophoto craze. NASA photographer Bill Ingalls took this beautiful image at The Peace Monument on the grounds of the United States Capitol, in Washington D.C. :
A perigree full moon or supermoon is seen over the The Peace Monument on the grounds of the United States Capitol, Sunday, August 10, 2014, in Washington. A supermoon occurs when the moon’s orbit is closest (perigee) to Earth at the same time it is full. Credit: (NASA/Bill Ingalls)
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
The "super moon" of August 2014 captured by Expedition 40's Oleg Artemyev on the International Space Station. Credit: OlegMKS / Twitter
With the full Moon approaching just a little bit closer than Earth to usual, a cosmonaut on the International Space Station took a few moments of his time to capture a few shots of it setting behind the Earth. Oleg Artemyev was just a shade closer to that Moon than the rest of us, and the sequence of pictures (below the jump) is stunning.
As Universe Today’s David Dickinson explained last week, the so-called “supermoon” refers to a phenomenon where the full Moon falls within 24 hours of perigee (closest approach to the Earth.) We’re in a cycle of supermoons right now, with this weekend’s the second in a three-part cycle this year.
The Moon appears about 14% bigger between its furthest and closest approaches to Earth. While the difference is subtle in the sky, it does produce higher tides on Earth (with an example being Hurricane Sandy in 2012.)
Technically the perigee happened August 10 at 6:10 p.m. UTC (2:10 p.m. EDT), but people (including Artemyev) took several pictures of the moon a bit before and after that time. One example from our Universe Today Flickr pool is at the bottom of this post. You can see more examples on Flickr.
The July 2014 Supermoon rising over the University of Texas at Austin Tower. Credit: Mark Ezell, used with permission.
You could be forgiven for thinking this summer that the “supermoon” is now a monthly occurrence. But this coming weekend’s Full Moon is indeed (we swear) the closest to Earth for 2014.
What’s going on here? Well, as we wrote one synodic month ago — the time it takes for the Moon to return to the same phase at 29.5 days — we’re currently in a cycle of supermoons this summer. That is, a supermoon as reckoned as when the Full Moon falls within 24 hours of perigee, a much handier definition than the nebulous “falls within 90% of its orbit” proposed and popularized by astrologers.
A super-sized shot of the July 2014 supermoon. Credit: Russell Bateman.
The supermoons for 2014 fall on July 13th, August 10th and September 8th respectively. You could say that this weekend’s supermoon is act two in a three act movement, a sort of Empire Strikes Back to last month’s A New Hope.
Now for the specifics: Full Moon this weekend occurs on August 10th at 18:10 Universal Time (UT) or 2:10 PM EDT. The Moon will reach perigee or its closest point to the Earth at 17:44 UT/1:44 PM EDT just 26 minutes prior to Full, at 55.96 Earth radii distant or 356,896 kilometres away. This is just under 500 kilometres shy of the closest perigee that can occur at 356,400 kilometres distant. Perigee was closer to Full phase time-wise last year on June 23rd, 2013, but this value won’t be topped or tied again until November 25th, 2034. The Moon will be at the zenith and closest to the surface of the Earth at the moment it passes Full over the mid-Indian Ocean on Sunday evening nearing local midnight.
The 99.8% Full Moon from July 2014. Credit: Stephen Rahn.
Now for a reality check: The August lunar perigee only beats out the January 1st approach of the Moon for the closest of 2014 by a scant 25 kilometres. Perigees routinely happen whether the Moon is Full or not, and they occur once every anomalistic month, which is the average span from perigee-to-perigee at 27.6 days. This difference between the anomalistic and synodic period causes the coincidence that is the supermoon to precess forward about a month a year. You can see our list of supermoon seasons out until 2020 here.
A comparison of lunar distance (dark line) with phase (grey line) for 2014. Note that 0.5 denotes Full, while 0 denotes New phase. Credit: Darekk2, Wikimedia Commons graphic under a 3.0 Unported license.
And don’t forget, the Moon actually approaches you to the tune of about half of the radius of the Earth while it rises to the zenith, only to recede again as it sinks back down to the horizon. The rising Full Moon on the horizon only appears larger mainly due to an illusion known as the Ponzo Effect.
The apparent size of the Moon varies about 14% in angular diameter from 29.3′ (known as an apogee “mini-Moon”) to 34.1′ at its most perigee “super-size” as seen from the Earth.
The July 2014 supermoon on the rise. Credit: Brad Timerson @btimerson.
Astronomers prefer the use of the term Perigee Full Moon, but the supermoon meme has taken on a cyber-life of its own. Of course, we’ve gone on record before and stated that we prefer the more archaic term Proxigean Moon, but the supermoon seems here to stay.
And as with many Full Moon myths, this week’s supermoon will be implicated in everything from earthquakes to lost car keys to other terrestrial woes, though of course no such links exist. Coworkers/family members/strangers on Twitter will once again insist it was “the biggest ever,” and claim it took up “half the sky” as they unwittingly take part in an impromptu psychological perception test.
The July supermoon shot through a blue filter… I wonder just how rare a “Super-Blue Moon” might be? Credit: Talia Landman @taliaeliana.
Fun fact: you could ring local the horizon with 633 supermoons!
And of course, many a website will recycle their supermoon posts, though of course not here at Universe Today, as we bake our science fresh daily.
So what can you expect? Well, a perigee Full Moon can make for higher than usual tides. New York City residents had the bad fortune of a Full Moon tidal surge in 2012 when Hurricane Sandy made landfall. Though there doesn’t seem to be a chance for a repeat of such an occurrence in 2014 in the Atlantic, super-typhoon Halong is churning towards the Japanese coastline for landfall this weekend…
The rising Waxing Gibbous Moon on the evening of August 9th. Credit: Stellarium.
Observationally, Full Moon is actually a lousy time for astronomical observations, causing many a deep sky astrophotographer to instead stay home and visit the family, while lurking astrophotography forums and debunking YouTube UFO videos.
Pro-tip: want your supermoon photo/video to go viral? Shoot the rising Moon just the evening prior when it’s waxing gibbous but nearly Full. Not only will it be more likely to be picked up while everyone is focused on supermoon lunacy, but you’ll also have the added bonus of catching the Moon silhouetted against a low-contrast dusk sky. We have a pre-supermoon rising video from a few years back that still trends with each synodic period!
Well, that’s it ‘til September, when it’ll be The Return (Revenge?) of the Supermoon. Be sure to send those pics in to Universe Today’s Flickr forum, you just might make the supermoon roundup!
Screenshot from Thierry Legault's video of the Bastille Day fireworks from the Eiffel Tower, July 14, 2014.
Who had the best view of the Bastille Day fireworks last night? From this lovely video from astrophotographer Thierry Legault, it appears the low-hanging, bright waning Moon may have had the preferred vantage point to watch the fine pyrotechnics from the Eiffel Tower. But Thierry had a pretty good view, as well! He told us he took this video from a hill a few kilometers west of Eiffel Tower.
The big proxigean full Moon rises over Daganzo de Arriba, near Madrid, Spain on July 12, 2014. Credit and copyright: Alvaro Ibañez Perez.
Did you hear there was something special about the full Moon this weekend… that it would be, well… really super? I heard about it on every newscast I watched or listened to. Even xkcd got into the ‘Supermoon’ craze. The July “Buck” Moon was the first of three Supermoons on tap for 2014, where the Moon is at its perigee, the closest point to Earth in its orbit, close to the time when it is “officially” full.
If you didn’t hear about it, (or weren’t paying attention) you may not have noticed anything different, as its not radically different from a regular full Moon. Read all the detail of what a Supermoon is here. But as Geoff Chester of the US Naval Observatory, said on NASA’s website, “However, if it gets people out and looking at the night sky and maybe hooks them into astronomy, then it’s a good thing,”
And people were out with their cameras, too! Here’s a great collection of full Moon images from this weekend, as seen in our Flickr Gallery.
An over-exposed beauty showing the full Moon rising through the clouds on July 12, 2014 near Bromsgrove, England, United Kingdom. Credit and copyright: Sarah and Simon Fisher.The rising “super moon” of July 12, 2014, rising above a canola field in southern Alberta, Canada. Credit and copyright: Alan Dyer/Amazing Sky Photography.A Mississippi Super Moonscape on July 12, 2014. Credit and Copyright: Veronica M Photography.The ‘Supermoon’ setting on the morning of July 13, 2014 at around 6 am local time near Kapiolani, Honolulu, Hawaii. Credit and copyright: Henry Weiland.A 3-exoposure of the full Moon on July 12, 2014, taken near Cap-Rouge, Quebec City, Quebec, Canada. Credit and copyright: Denis Marquis. The July 12, 2014 Supermoon or perigee full moon shares the night sky with fireworks from a display in Chester, New York. Credit and copyright: Tom Bushey.Moonrise with a flyby. July 13, 2014 from the UK. Credit and copyright: SculptorLil on Flickr.The rising waning Moon on July 13, 2014, from near Bedfordshire, UK. Credit and copyright: DawnSunrise on Flickr.
Be advised that this month’s big full Moon was not the closest of the year. The closest Full Moon of 2014 occurs next month on August 10th at 18:11 Universal Time (UT) or 1:44 PM EDT. On that date, the Moon reaches perigee or its closest approach to the Earth at 356,896 kilometres distant at 17:44, less than an hour from Full.
The perigee Full Moon of June 22nd, 2013. Credit: Russell Bateman (@RussellBateman1)
‘Tis the season once again, when rogue Full Moons nearing perigee seem roam the summer skies to the breathless exhortations of many an astronomical neophyte at will. We know… by now, you’d think that there’d be nothing new under the Sun (or in this case, the Moon) to write about the closest Full Moons of the year.
But love ‘em or hate ‘em, tales of the “Supermoon” will soon be gracing ye ole internet again, with hyperbole that’s usually reserved for comets, meteor showers, and celeb debauchery, all promising the “biggest Full Moon EVER…” just like last year, and the year be for that, and the year before that…
How did this come to be?
What’s happening this summer: First, here’s the lowdown on what’s coming up. The closest Full Moon of 2014 occurs next month on August 10th at 18:11 Universal Time (UT) or 1:44 PM EDT. On that date, the Moon reaches perigee or its closest approach to the Earth at 356,896 kilometres distant at 17:44, less than an hour from Full. Of course, the Moon reaches perigee nearly as close once everyanomalistic month (the time from perigee-to-perigee) of 27.55 days and passes Full phase once every synodic period (the period from like phase to phase) with a long term average of 29.53 days.
Moon rise on the evening of July 11th, 2014 as seen from latitude 30 degrees north. Credit: Stellarium.
And the August perigee of the Moon only beats out the January 1st, 2014 perigee out by a scant 25 kilometres for the title of the closest perigee of the year, although the Moon was at New phase on that date, with lots less fanfare and hoopla for that one. Perigee itself can vary from 356,400 to 370,400 kilometres distant.
But there’s more. If you consider a “Supermoon” as a Full Moon falling within 24 hours of perigee, (folks like to play fast and loose with the informal definitions when the Supermoon rolls around, as you’ll see) then we actually have a trio of Supermoons on tap for 2014, with one this week on July 12th and September 9th as well.
What, then, is this lunacy?
Well, as many an informative and helpful commenter from previous years has mentioned, the term Supermoon was actually coined by an astrologer. Yes, I know… the same precession-denialists that gave us such eyebrow raising terms as “occultation,” “trine” and the like. Don’t get us started. The term “Supermoon” is a more modern pop culture creation that first appeared in a 1979 astrology publication, and the name stuck. A more accurate astronomical term for a “Supermoon” is a perigee-syzygy Full Moon or Proxigean Moon, but those just don’t seem to be able to “fill the seats” when it comes to internet hype.
One of the more arcane aspects set forth by the 1979 definition of a Supermoon is its curiously indistinct description as a “Full Moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit.” This is a strange demarcation, as it’s pretty vague as to the span of distance (perigee varies, due to the drag of the Sun on the Moon’s orbit in what’s known as the precession of the line of apsides) and time. The Moon and all celestial bodies move faster near perigee than apogee as per Kepler’s 2nd Law of planetary motion.
A photo essay comparing Full Moon sizes and appearance from one Supermoon to the next, spanning 2011-2012. Credit: Marion Haligowski/RadicalRetinscopy. Used with permission.
We very much prefer to think of a Proxigean Moon as defined by a “Full Moon within 24 hours of perigee”. There. Simple. Done.
And let’s not forget, Full phase is but an instant in time when the Moon passes an ecliptic longitude of 180 degrees opposite from the Sun. The Moon actually never reaches 100% illumination due to its 5.1 degree tilt to the ecliptic, as when it does fall exactly opposite to the Sun it also passes into the Earth’s shadow for a total lunar eclipse.
-Check out this animation of the changing size of the Moon and its tilt — known as libration and nutation, respectively — as seen from our Earthly perspective over the span of one lunation.
The truth is, the Moon does vary from 356,400 to 406,700 kilometres in its wonderfully complicated orbit about our fair world, and a discerning eye can tell the difference in its size from one lunation to the next. This means the apparent size of the Moon can vary from 29.3’ to 34.1’ — a difference of almost 5’ — from perigee to apogee. And that’s not taking into account the rising “Moon illusion,” which is actually a variation of an optical effect known as the Ponzo Illusion. And besides, the Moon is actually more distant when its on the local horizon than overhead, to the tune of about one Earth radius.
Like its bizarro cousin the “minimoon” and the Blue Moon (not the beer), the Supermoon will probably now forever be part of the informal astronomical lexicon. And just like recent years before 2014, astronomers will soon receive gushing platitudes during next month’s Full Moon from friends/relatives/random people on Twitter about how this was “the biggest Full Moon ever!!!”
The perigee Full Moon of May 5th, 2012. Credit: Stephen Rahn (@StephenRahn13)
Does the summer trio of Full Moons look bigger to you than any other time of year? It will be tough to tell the difference visually over the next three Full Moons. Perhaps a capture of the July, August and September Full Moons might just tease out the very slight difference between the three.
And for those preferring not to buy in to the annual Supermoon hype, the names for the July, August and September Full Moons are the Buck, Sturgeon and Corn Moon, respectively. And of course, the September Full Moon near the Equinox is also popularly known as the Harvest Moon.
And in case you’re wondering, or just looking to mark your calendar for the next annual “largest Full Moon(s) of all time,” here’s our nifty table of Supermoons through 2020, as reckoned by our handy definition of a Full Moon falling within 24 hours of perigee.
So what do you say? Let ‘em come for the hype, and stay for the science. Let’s take back the Supermoon.
