Posted on by David Dickinson

See the Smallest Full Moon of 2014: It’s the “Return of the Mini-Moon”

Last month's rising "Mini-Moon" of 2013. (Photo by Author)

 Last month, (and last year) we wrote about the visually smallest Full Moon of 2013. Now, in a followup  act, our natural satellite gives  us an even more dramatic lesson in celestial mechanics with an encore performance just one lunation later with the smallest Full Moon of 2014.

We’ve noted the advent of the yearly Mini-Moon, a bizzaro twin to the often over-hyped “SuperMoon,” or Proxigean Full Moon. Occurring approximately six months apart, you can always expect lunar apogee to roughly coincide with the instant of a Full Moon about half a year after it coincides with perigee. In fact, the familiar synodic period that it takes the Moon to return to like phase (such as Full back to Full) of 29.5 days has a lesser known relative known as the anomalistic month, which is the period of time it takes the Moon to return to perigee at 27.55 days.

But the circumstances for “Mini-Moon 2014” are exceptional. The first Full Moon of the year occurs on the night of January 15th at 11:52 PM EST/4:52 Universal Time (on January 16th). This is just 2 hours and 59 minutes after the Moon reaches apogee at 406,536 kilometres distant at 8:53 PM EST/1:53 UT. This isn’t the farthest apogee that occurs in 2014, but it’s close: the Moon is just 32 kilometres more distant on July 28th, 2014. Apogee can vary from 404,000 to 406,700 kilometres, and this month’s apogee falls just 164 kilometres short of the maximum value.

As you can see, this year’s Mini-Moon falls extremely close to apogee… in fact, you have to go all the way back to the Full Moon of November 18th, 1994 to find a closer occurrence, and this year’s won’t be topped until May 13th, 2052! The Moon will appear only 29’ 23” in size on Wednesday night at moonrise, very close to its minimum possible value of 29’ 18”. This is also almost 5 arc minutes smaller than the largest “Super-Moon” possible.

Cool factoid: you actually move closer to the Moon as it rises, until it transits your local meridian and you begin moving away from it, all due to the Earth’s rotation. You can thus gain and lose a maximum of one Earth radii distance from the Moon in the span one night.

We also just passed the most northern Moon of 2014, as it reached a declination of 19 degrees 24’ north this morning at 8:00 UT/3:00 AM EST. This is a far cry from the maximum that can occur, at just over 28 degrees north. This is because we’re headed towards a “shallow year” as the Moon’s motion bottoms out relative to the ecliptic in 2015 and once again begins to widen out in its 18+ year cycle to its maximum in 2024-25.

The position of the Moon Monday night on January 13th in Orion. Credit: Stellarium
The position of the Moon Monday night on January 13th in Orion. Credit: Stellarium

This week’s Moon also visits some interesting celestial targets as well. The waxing gibbous Moon sits just 5.1 degrees south of the open cluster M35 tonight. Notice something odd about the Moon’s position Monday night? That’s because it is passing through Orion the Hunter, one of the six non-zodiacal constellations that it can be found in. Can you name the other five? Hint: one was the “13th sign of the zodiac that created a non-traversy a few years back.

On Tuesday evening, the Moon passes six degrees from the planet Jupiter. This presents a fine time to try and spot the planet in the daytime to the Moon’s upper left, just a few hours prior to sunset.

The Moon will also occult the +3.6 magnitude star Lambda Geminorum on January 15th for observers in northwestern North America. In fact, viewers along a line crossing central British Columbia will witness a spectacular graze along the lunar limb as the star winks out behind lunar mountains and pops into view as it shines through lunar valleys along the edge of the Moon. This can make for an amazing video capture, we’re just throwing that out there…

The occultation footprint for Lambda Geminorum for January 15th. (Created using Occult 4.01 software)
The occultation footprint for Lambda Geminorum for January 15th. (Created using Occult 4.10.11 software)

In addition to being this year’s Mini-Moon, the January Full Moon is also known as the Wolf Moon in the tradition of the Algonquin Native Americans, as January was a time of the mid-winter season when starving wolf packs would howl through the long cold night. The January Full Moon is also sometimes referred to as “The Moon after Yule,” marking the first Full Moon after Christmas.

And just when is the next Super Moon, you might ask? Well, 2014 has three Full Moons occurring within 24 hours of perigee starting on July 15th and finishing up on September 8th. But the most notable is on August 10th, when the Moon passes perigee just 27 minutes from Full. Expect it to be preceded by the usual lunacy that surrounds each annual “Super Moon” as we once again bravely battle the forces of woo and describe just exactly what a perigee Full Moon isn’t capable of. Yes, we still prefer the quixotic term “Proxigean Moon,” but there you go.

Also, be sure to wave a China’s Chang’e-3 lander and rover in the Bay of Rainbows (Sinus Iridum) as you check out this week’s Full Moon, as it just experienced its first lunar sunrise this past week.

Be sure to send those Mini-Moon pics and more in to Universe Today, and let’s get this week’s #MiniMoon trending on Twitter!

Posted on by Nancy Atkinson

The 2013 Super and Mini Moon Together in One Photo

A composition of the nearest and farthest 2013 full moons, with the SuperMoon of June on the left and the MiniMoon of December on the right. Credit and copyright: Giuseppe Petricca.

Astrophotographer Giuseppe Petricca from Pisa, Tuscany, Italy managed to capture two of the very ‘special’ full Moons from 2013 and created a comparative mosaic. Here is both the 2013 “SuperMoon” in June – when the Moon is the closest to Earth in its orbit and visually largest – and the recent December 2013 “MiniMoon” — the most distant and visually smallest Full Moon of the year.

“I was amazed, to say the least, from the actual difference!” Petricca told Universe Today via email. “The motto ‘It’s not that evident until you, by yourself, get to notice it!’ applies perfectly to this situation.

While with naked eye, the full Moon seems about the same size every month, the difference in its visual size is clearly visible via pictures. Of course, the Moon itself doesn’t change size, it’s just how big or small it appears in the sky due to the eccentricities in its orbit around Earth.

The two pictures were both taken at the same focal length, with a simple non reflex camera, a Nikon P90, on tripod, with matching ISO speed and exposure, at ISO 100, f5.0, 1/200″. Both taken from Pisa, Tuscany, Italy.

You can read all about the recent “MiniMoon” here, and find out more about the mechanics of the “SuperMoon” here.

Posted on by David Dickinson

Tonight: The Rise of the 2013 “Mini-Moon”

The December 2010 Solstice Moon.

  The final Full Moon of 2013 occurs tonight, and along with it comes something special: the most distant and visually smallest Full Moon of 2013.

Why doesn’t the annual “mini-moon” receive the same fanfare and hype that the yearly perigee – or do you say Proxigean to be uber-obscure – “supermoon” does? The smallest Full Moon of the year does appear to have a public relations problem in this regard. But as you’ll see, the circumstances for this week’s Full Moon are no less fascinating.

The exact timing of tonight’s Full Moon occurs at 4:28 AM EST/9:28 Universal Time (UT) on Tuesday, December 17th. This occurs just two days and 14 hours prior to the Moon reaching apogee on December 19th at 6:50PM EST/23:50 UT at 406,267 kilometres distant. This is one of the three most distant apogees of 2013, and the closest to Full for the year. It’s also with 500 kilometres of the most distant apogee than can occur, as the Moon’s apogee can vary between ~404,000 and 406,700 kilometres distant.

Tonight’s Full Moon will have an apparent angular diameter of around 29.8’ arc minutes, just a shade lower than the usual value quoted of around half a degree or 30’. The visual size of the Moon as seen from the Earth varies about 12% from 34.1’ to 29.3’. Also, the Moon is also about half an Earth radius more distant when it’s on the local horizon versus at the zenith overhead!

This is also the closest Full Moon to the December solstice, which occurs four days later on Saturday, December 21st at 12:11 PM EST/17:11 UT. This marks the start of astronomical summer in the southern hemisphere and the beginning of the winter season in the north. Think of tonight’s Full Moon as a sort of “placeholder,” marking the point at which the Sun will occupy during the June solstice on the Gemini-Taurus border.

This all means that tonight’s Full Moon rides high for northern hemisphere residents towards local midnight. But the “Long Night’s Moon” of 2013 is rather lackluster in terms of declination. While it’s the northernmost Full Moon of 2013 at a declination of +18.7 degrees, it’s a far cry from the maximum declination of +28.72 degrees (the angle of the ecliptic plus the tilt of the Moon’s orbit) that it can achieve. This only occurs every 18.6 years and last occurred in 2006 and will happen again around 2025. We’re currently headed towards a shallow minimum for the Moon’s orbit in 2015. Ancient European and Native American cultures both knew of this cycle of high-flying moons.

Not weird enough? The next “most distant Full Moon of the Year” happens only one lunation later on January 16th… within just 2 hours of apogee! Perhaps January’s Full Moon is due notoriety as a “Super-Mini Moon?” Such a pairing of “mini-moons” last occurred on 2004-2005 and will next occur on 2021-2022.

The footprint for the lunar occultation of M67. (Created by the author using Occult 4.0)
The footprint for the lunar occultation of M67. (Created by the author using Occult 4.1)

The Moon also visits some other celestial sights this week. After passing five degrees north of Jupiter on December 19th, the Moon heads towards an occultation of the open cluster M67 in the constellation Cancer on December 21st for northern North America. Though the Moon will be waning gibbous, it might just be possible to note the reappearance of the cluster on the Moon’s dark limb. Other occultations for the remainder of December by the Moon include an occultation of Spica on December 27th for northern Asia, Saturn on December 29th for Antarctica, and +3.6th magnitude star Lambda Geminorum for Canada on December 18th.

The passing of the Full Moon also means it will be entering into the morning sky, which also means bad news for viewers of the Ursid meteor shower which peaks on December 22nd and hunters of Comet C/2013 R1 Lovejoy, currently shining at +5th magnitude in the constellation Hercules low in the dawn.

Moon crossing Orion.
Moon crossing Orion this week. (Credit: Stellarium).

The keen-eyed may notice the Moon also transits through the northern end of the non-zodiacal constellation of Orion on Tuesday, December 17th. Did you know that the Moon can actually stray far enough away from the ecliptic to cross through 18 constellations? The Six non-zodiacal constellations it can transit are: Orion, Ophiuchus, Corvus, Sextans, Auriga and Cetus.

Other names for the December Full Moon include the Yule, Oak, and Cold Moon.

Finally, a new Earthly ambassador is now roaming the lunar surface.

China’s Chang’E-3 spacecraft landed on the Moon just outside of the Bay of Rainbows (Sinus Iridum) near Montes Recti in the northern section of the Mare Imbrium on Saturday, December 14th. The landing site is visible now on the lunar nearside, and can be seen with that new Christmas telescope you’ve been itching to try out. Look for the Sinus Iridum as a wide crescent scarp, a sort of “notch” in the top of Mare Imbrium:

Finding the landing site of Chang'e-3. Photos and graphics by author.
Finding the landing site of Chang’e-3. Photos and graphics by author.

China’s Yutu or “Jade Rabbit” rover has been beaming back some splendid images of the lunar surface!

So don’t let the cold temperatures deter you from exploring the lunar surface, and the strange but fascinating motions of our nearest natural celestial neighbor. Dress warm and be sure this Christmas season to raise a glass of ye ole Nog to the Solstice/Yule Moon.

Posted on by Nancy Atkinson

Timelapse: Super Moon Rising Over the Rocky Mountians

A series of photos combined to show the rise of the July 22, 2013 ‘super’ full moon over the Rocky Mountains, shot near Vail, Colorado, at 10,000ft above sea level in the White River National Forest. Moon images are approximately 200 seconds apart. Credit and copyright: Cory Schmitz

Astrophotographer Cory Schmitz braved a brown bear in order to capture some wonderful images of the full Moon rise on July 22, 2013. This composite shows a series of images of the moonrise, and below is a beautiful timelapse.

This perigee Moon, a.k.a “Super Moon” was the third and final of the big full Moons for 2013. However, as astrophysicist Neil DeGrasse Tyson mentioned on Twitter, it is “Okay to call tonight’s Full Moon “super” but only if you would call a 13-inch pizza “super” compared with a 12-inch pizza.”

You can catch more of Cory with Fraser on the Virtual Star Parties on Sunday nights. Below are a couple of more great scenes from Cory’s full Moon experience:

A bear sits right on the spot where Cory Schmitz wanted to set up his photography equipment. Image courtesy Cory Schmitz.
A bear sits right on the spot where Cory Schmitz wanted to set up his photography equipment. Image courtesy Cory Schmitz.
The full-moon illuminated landcape, overlooking Interstate 70, near Vail, Colorado. Credit and copyright: Cory Schmitz.
The full-moon illuminated landcape, overlooking Interstate 70, near Vail, Colorado. Credit and copyright: Cory Schmitz.
Posted on by David Dickinson

Super-Moon Monday: The 3rd (& Final?) Act

The gibbous Moon rising rising over the Andes Mountains in Chile. (Credit: @WladimirPulgarG/Flickr).

“Once more into the breach, my dear friends…”

Such a quip may be deemed appropriate as we endured the media onslaught this past weekend for the third and final perigee Full Moon of 2013.

Tonight, on Monday, July 22nd, the Moon reaches Full at 18:15 Universal Time (UT)/4:15 PM EDT. This is only 21.9 hours after reaching perigee, or the closest point in its orbit at 358,401 kilometres from the Earth on the Sunday evening at 20:28 UT. Continue reading “Super-Moon Monday: The 3rd (& Final?) Act”

Posted on by David Dickinson

Happy (or is it Merry?) Aphelion This Friday

Solar apparent size- perihelion versus aphelion 2012.

This 4th of July weekend brings us one more reason to celebrate. On July 5th at approximately 11:00 AM EDT/15:00 UT, our fair planet Earth reaches aphelion, or its farthest point from the Sun at 1.0167 Astronomical Units (A.U.s) or 152,096,000 kilometres distant.

Though it may not seem it to northern hemisphere residents sizzling in the summer heat, we’re currently 3.3% farther from the Sun than our 147,098,290 kilometre (0.9833 A.U.) approach made in early January.

We thought it would be a fun project to capture this change. A common cry heard from denier circles as to scientific facts is “yeah, but have you ever SEEN it?” and in the case of the variation in distance between the Sun and the Earth from aphelion to perihelion, we can report that we have!

We typically observe the Sun in white light and hydrogen alpha using a standard rig and a Coronado Personal Solar Telescope  on every clear day. We have two filtered rigs for white light- a glass Orion filter for our 8-inch Schmidt-Cassegrain, and a homemade Baader solar filter for our DSLR. We prefer the DSLR rig for ease of deployment. We’ve described in a previous post how to make a safe and effective solar observing rig using Baader solar film.

Our solar imaging rig.
Our primary solar imaging rig. A Nikon D60 DSLR with a 400mm lens + a 2x teleconverter and Baader solar filter. Very easy to employ!

We’ve been imaging the Sun daily for a few years as part of our effort to make a home-brewed “solar rotation and activity movie” of the entire solar cycle.  We recently realized that we’ve imaged Sol very near aphelion and perihelion on previous years with this same fixed rig, and decided to check and see if we caught the apparent size variation of our nearest star. And sure enough, comparing the sizes of the two disks revealed a tiny but consistent variation.

It’s a common misconception that the seasons are due to our distance from the Sun. The insolation due to the 23.4° tilt of the rotational axis of the Earth is the dominant driving factor behind the seasons. (Don’t they still teach this in grade school? You’d be surprised at the things I’ve heard!) In the current epoch, a January perihelion and a July aphelion results in milder climatic summers in the northern hemisphere and more severe summers in the southern. The current difference in solar isolation between hemispheres due to eccentricity of Earth’s orbit is 6.8%.

The orbit of the Earth also currently has one of the lowest eccentricities (how far it deviates for circular) of the planets at 0.0167, or 1.67%. Only Neptune (1%) and Venus (0.68%) are “more circular.”

The orbital eccentricity of the Earth also oscillates over a 413,000 year period between 5.8% (about the same as Saturn) down to 0.5%. We’re currently at the low end of the scale, just below the mean value of 2.8%.

Variation in eccentricity is also coupled with other factors, such as the change in axial obliquity the precession of the line of apsides and the equinoxes to result in what are known as Milankovitch cycles. These variations in extremes play a role in the riddle of climate over hundreds of thousands of years.  Climate change deniers like to point out that there are large natural cycles in the records, and they’re right – but in the wrong direction. Note that looking solely at variations in the climate due to Milankovitch cycles, we should be in a cooling trend right now.  Against this backdrop, the signal of anthropogenic climate forcing and global dimming of albedo (which also masks warming via cloud cover and reflectivity) becomes even more ominous.

Aphelion can presently fall between July 2nd at 20:00 UT (as it did last in 1960) and July 7th at 00:00 UT as it last did on 2007.  The seemingly random variation is due to the position of the Earth with respect to the barycenter of the Earth-Moon system near the time of aphelion. The once every four year reset of the leap year (with the exception of the year 2000!) also plays a lesser role.

Perihelion and aphelion vs the solstices and equinoxes, an exagarated view.
Perihelion and aphelion vs the solstices and equinoxes, an exaggerated view. (Wikimedia Commons image under a 3.0 Unported Attribution-Share Alike license. Author Gothika/Doudoudou).

I love observing the Sun any time of year, as its face is constantly changing from day-to-day. There’s also no worrying about light pollution in the solar observing world, though we’ve noticed turbulence aloft (in the form of bad seeing) is an issue later in the day, especially in the summertime.  The rotational axis of the Sun is also tipped by about 7.25° relative to the ecliptic, and will present its north pole at maximum tilt towards us on September 8th. And yes, it does seem strange to think in terms of “the north pole of the Sun…”

We’re also approaching the solar maximum through the 2013-2014 time frame, another reason to break out those solar scopes.  This current Solar Cycle #24 has been off to a sputtering start, with the Sun active one week, and quiet the next. The last 2009 minimum was the quietest in a century, and there’s speculation that Cycle #25 may be missing all together.

And yes, the Moon also varies in its apparent size throughout its orbit as well, as hyped during last month’s perigee or Super Moon. Keep those posts handy- we’ve got one more Super Moon to endure this month on July 22nd. The New Moon on July 8th at 7:15UT/3:15 AM EDT will occur just 30 hours after apogee, and will hence be the “smallest New Moon” of 2013, with a lot less fanfare. Observers worldwide also have a shot at catching the slender crescent Moon on the evening of July 9th. This lunation and the sighting of the crescent Moon also marks the start of the month of Ramadan on the Muslim calendar.

Be sure to observe the aphelion Sun (with proper protection of course!) It would be uber-cool to see a stitched together animation of the Sun “growing & shrinking” from aphelion to perihelion and back. We could also use a hip Internet-ready meme for the perihelion & aphelion Sun- perhaps a “MiniSol?” A recent pun from Dr Marco Langbroek laid claim to the moniker of “#SuperSun;” in time for next January’s perihelion;

Marco quote

Could a new trend be afoot?

Posted on by Nancy Atkinson

Astrophoto: Houston Super Moonrise

37 separate images showing the movement of the Moon as it rises behind the buildings in downtown Houston, Texas on June 22, 2013. Credit and copyright: Sergio Garcia Rill/SGR Photo.

While we recently posted a huge batch of images from the recent “Super Moon,” this new image from Sergio Garcia Rill in Houston is something special. It’s a composite photo of the Moonrise on June 22nd, and is a mosaic made from 37 separate images that show the Moon rising over the course of three hours, with the buildings of downtown Houston in the foreground.

“I stayed in place for over three hours,” Sergio explained on Flickr. “The hardest part was selecting which shots showed a sequential movement of the Moon, since I was altering shutter speeds between shots to compensate for changing light conditions.”

The full Moon of June 2013 was at perigee — or at its closest point in its orbit to Earth, and appeared up to 14% bigger and 30% brighter than other full Moons of 2013.

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.

Posted on by Nancy Atkinson

‘Super Moon’ Images from Around the World, June 2013

The perigee 'Super Moon' of June 23, 2013 (21:43 PHT) over Marikina City, Philippines compared to the apogee Moon of November, 2012. Credit and copyright: Raven Yu.

The full Moon of June 23, 2013 was the largest Moon of the year. This so-called “Super Moon” was at perigee — or at its closest point in its orbit to Earth, and was 14% bigger and 30% brighter than other full Moons of 2013.

But, if you looked up at the Moon last night and didn’t know about this, you may not have noticed! Some claims circulating on the internet tended to exaggerate how large the Moon would actually appear. However, that doesn’t mean the Moon wasn’t photogenic last night! The Moon is always a great target for photography or just gazing with your own eyes, and these images from Universe Today readers attest to the beauty of our closest companion in the night sky.

This lead image from Raven Yu from the Philippines shows the difference in size between last night’s perigee Moon and the apogee Moon (when it was farthest from Earth during its orbit) last November.

If you want to find out more about the science of the perigee Super Moon, read our detailed article here.

See more beautiful images, below!

Three different views of the Moon over Italy during the night of June 23, 2013 helps debunk the optical illusion of the Moon looking bigger when it's low on the horizon. Credit and copyright: Giuseppe Petricca.
Three different views of the Moon over Italy during the night of June 23, 2013 helps debunk the optical illusion of the Moon looking bigger when it’s low on the horizon. Credit and copyright: Giuseppe Petricca.

Three different pictures of the Moon from June 23, shared by Guiseppe Petricca from Italy, detailing not only the perigee Super Moon, but the ‘Moon Illusion” — of how the Moon looks bigger when it is close to the horizon.

“The middle one is the Moon at culmination in the local sky and the other two are taken as low as possible my local horizon permitted,” Guiseppe said via email. “Doing this, I managed to obtain two results: the first one is observing the different colours that due to the Rayleigh Scattering, ‘paint’ our satellite, when it’s low on its elevation. The second one is that, keeping a fixed magnification (24x – 110mm) one can easily debunk the optical illusion of the ‘bigger moon when it’s low on the horizon’. Since, if you observe carefully, the lower two ‘Moons’ are smaller than the higher one. However, the total personal experience is surely wonderful!! And the ‘horizon illusion’ makes you really think that the Moon is way bigger that the reality.”

The Supermoon rising on June 23rd, 22:40 pm above the forest canopy top in Puerto Rico. This is a 6 panel mosaic. Credit and copyright: Efrain Morales, Jaicoa Observatory.
The Supermoon rising on June 23rd, 22:40 pm above the forest canopy top in Puerto Rico. This is a 6 panel mosaic. Credit and copyright: Efrain Morales, Jaicoa Observatory.
The Super Moon on June 23, 2013 as seen over Malta. Credit and copyright: Leonard E. Mercer.
The Super Moon on June 23, 2013 as seen over Malta. Credit and copyright: Leonard E. Mercer.
The perigee 'Super Moon' of June 23, 2013 as seen over Sesimbra, Portugal and the church Nossa Senhora do Castelo. Credit and copyright: Miguel Claro.
The perigee ‘Super Moon’ of June 23, 2013 as seen over Sesimbra, Portugal and the church Nossa Senhora do Castelo. Credit and copyright: Miguel Claro.

Miguel Claro captured this beautiful image of the huge full Moon rising above a Moorish castle in Sesimbra, Portugal. “The church Nossa Senhora do Castelo stands on the spot where king Sancho I built a Romanesque chapel in the early 13th century,” Miguel said via email. “This image was captured 2 km away from the subject.” Miguel used a Canon 50D – ISO640; 1/80 sec. + ED80 APO refractor Astro Professional 560mm at f/7 taken on 23/06/2013 at 21h22.

The perigee Super Moon of June 23, 2013 as seen over São Paulo, Brazil. Time: 01:40 UTC, using a Maksutov Cassegrain Vixen 110 mm - F = 1035 mm - F/9.4 - Plano Focal - Nikon D3100 - 1/80 - ISO 200. Credit and copyright: Ednilson Oliveira.
The perigee Super Moon of June 23, 2013 as seen over São Paulo, Brazil. Time: 01:40 UTC, using a Maksutov Cassegrain Vixen 110 mm – F = 1035 mm – F/9.4 – Plano Focal – Nikon D3100 – 1/80 – ISO 200. Credit and copyright: Ednilson Oliveira.
An early image of the perigee Super Moon -- the Moon setting the morning of June 23, 2013 just after 5 a.m. EDT over Toronto, Canada. ‘As I understand it perigee occurred between 7:11 - 7:13 a.m. EDT, so this was my ‘launch window’ to 'Shoot the Perigee Moon'. The atmosphere was thick with haze which dimmed the Moon substantially and allowed the surface maria to be photographed.’ Credit and copyright: Rick Ellis.
An early image of the perigee Super Moon — the Moon setting the morning of June 23, 2013 just after 5 a.m. EDT over Toronto, Canada. ‘As I understand it perigee occurred between 7:11 – 7:13 a.m. EDT, so this was my ‘launch window’ to ‘Shoot the Perigee Moon’. The atmosphere was thick with haze which dimmed the Moon substantially and allowed the surface maria to be photographed.’ Credit and copyright: Rick Ellis.
The perigee Super Moon rising over the floodwaters of the Bow River during a record flood that inundated many parts of southern Alberta around rivers, including here on the Siksika First Nations reserve. Credit and copyright: Alan Dyer/Astronomy Calgary/Amazing Sky Photography.
The perigee Super Moon rising over the floodwaters of the Bow River during a record flood that inundated many parts of southern Alberta around rivers, including here on the Siksika First Nations reserve. Credit and copyright: Alan Dyer/Astronomy Calgary/Amazing Sky Photography.
A 3-photo HDR image of the supermoon rising over downtown Tucson, Arizona. During the longer exposure the Moon gave out its own flare due to its intensity. Credit and copyright: Sean Parker/Sean Parker Photography.
A 3-photo HDR image of the supermoon rising over downtown Tucson, Arizona. During the longer exposure the Moon gave out its own flare due to its intensity. Credit and copyright: Sean Parker/Sean Parker Photography.
The full perigee Moon rising on June 23, 2013. Credit and copyright: Sculptor Lil on Flickr.
The full perigee Moon rising on June 23, 2013. Credit and copyright: Sculptor Lil on Flickr.
Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.
Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.
The perigee Super Moon on June 23, 2013, taken with a Skywatcher ED80 Refractor and a Canon 600D at prime focus. Best 20 of 40 images stacked in Registax 6. False colour removed as the Moon appeared dull red as it was so low in sky. Credit and copyright: James Lennie.
The perigee Super Moon on June 23, 2013, taken with a Skywatcher ED80 Refractor and a Canon 600D at prime focus. Best 20 of 40 images stacked in Registax 6. False colour removed as the Moon appeared dull red as it was so low in sky. Credit and copyright: James Lennie.
The view of June 23rd 2013 Supermoon from Trinidad and Tobago, West Indies (Caribbean). Credit and copyright: Apple Lilly. (This image is the right size to fit a Facebook cover image, the photographer says).
The view of June 23rd 2013 Supermoon from Trinidad and Tobago, West Indies (Caribbean). Credit and copyright: Apple Lilly. (This image is the right size to fit a Facebook cover image, the photographer says).

You can see more great images of this perigee Super Moon — and lots more great astrophotography at our Flickr group page.

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.

Posted on by David Dickinson

What is a Super Moon?

The 2011...

It’s a bird, it’s a plane it’s…

OK, it’s a bad gag, I know. But the movie Man of Steel isn’t the only thing that’s “super” about June this year. The closest full Moon of 2013 occurs on June 23, when it will be 356,991 kilometres from Earth, within 600 kilometres of its closest possible approach. When the Moon is closest to Earth in its orbit, it also appears just a bit larger in the sky. But that’s if you’re really paying attention, however!

Some claims circulating on the Internet tend to exaggerate how large the Moon will actually appear. And as for the assertions that the Moon will look bright purple or blue on June 23, that’s just not true. As seems to happen every year, the term “supermoon” has once again reared its (ugly?) head across ye ole Internet. Hey, it’s a teachable moment, a good time to look at where the term came from, and examine the wonderful and wacky motion of our Moon.

I’ll let you in on a small secret. Most astronomers, both of the professional and backyard variety, dislike the informal term “supermoon”. It arose in astrology circles over the past few decades, and like the term “Blue Moon” seems to have found new life on the Internet.  A better term from the annuals of astronomy for the near-coincidence of the closest approach of the Full Moon would be Perigee Full Moon. And if you really want to be archaic, Proxigean Moon is also acceptable.

On June 23, 2013, the Moon will be full at 7:32 AM EDT/ 11:32 UT, only 20 minutes after it reaches perigee, or its closest point to Earth in its orbit.

You can see the change in apparent size of the Moon (along with a rocking motion of the Moon known as nutation and libration) in this video from the Goddard Space Flight Center’s Scientific Visualization Studio. You can also see full animations for Moon phases and libration for 2013 from the northern hemisphere and southern hemisphere.

And all perigees are not created equal, either. Remember, a Full Moon is an instant in time when the Moon’s longitude along the ecliptic is equal to 180 degrees. Thus, the Full Moon rises (unless you’re reading this from high polar latitudes!) opposite as the Sun sets. Perigee also oscillates over a value of just over 2 Earth radii (14,000 km) from 356,400 to 370,400 km. And while that seems like a lot, remember that the average distance to the Moon is about 60 earth radii, or 385,000 km distant.

Astronomers yearn for kryptonite for the supermoon. The Moon passes nearly as close every 27.55 days, which is the time that it takes to go from one perigee to another, known as an anomalistic month. This is not quite two days shorter than the more familiar synodic month of 29.53 days, the amount of time it takes the Moon to return to similar phase (i.e. New to New, Full to Full, etc).

This offset may not sound like much, but 2 days can add up. Thus, in six months time, we’ll have perigee near New phase and the smallest apogee Full Moon of the year, falling in 2013 on December 19th. Think of the synodic and anomalistic periods like a set of interlocking waves, cycling and syncing every 6-7 months.

You can even see this effect looking a table of supermoons for the next decade;

Super Moons for the Remainder of the Decade 2013-2020.

Year

Date

Perigee Time

Perigee Distance

Time from Full

Notes

2013

June 23

11:11UT

356,989km

< 1 hour

2013

July 21

20:28UT

358,401km

-21 hours

2014

July 13

8:28UT

358,285km

+21 hours

2014

August 10

17:44UT

356,896km

< 1 hour

2014

September 8

3:30UT

358,387km

-22 hours

2015

August 30

15:25UT

358,288km

          +20 hours

2015

September 28

1:47UT

356,876km

-1 hour

Eclipse

2015

October 26

13:00UT

358,463km

-23 hours

2016

October 16

23:37UT

357,859km

+19 hours

Farthest

2016

November 14

11:24UT

356,511km

-2 hours

Closest

2017

December 4

8:43UT

357,495km

+16 hours

2018

January 1

21:56UT

356,565km

-4 hours

2019

January 21

19:59UT

357,344km

+14 hours

Eclipse

2019

February 19

9:07UT

356,761km

-6 hours

2020

March 10

6:34UT

357,122km

+12 hours

2020

April 7

18:10UT

356,908km

-8 hours
Sources: The fourmilab Lunar Perigee & Apogee Calculator & NASA’s Eclipse Website 2011-2020.Note: For the sake of this discussion, a supermoon is defined here as a Full Moon occurring within 24 hours of perigee. Other (often arbitrary) definitions exist!

Note that the supermoon slowly slides through our modern Gregorian calendar by roughly a month a year.

In fact, the line of apsides (an imaginary line drawn bisecting the Moon’s orbit from perigee to apogee) completes one revolution every 8.85 years. Thus, in 2022, the supermoon will once again occur in the June-July timeframe.

To understand why this is, we have to look at another unique feature of the Moon’s orbit. Unlike most satellites, the Moon’s orbit isn’t fixed in relation to its primaries’ (in this case the Earth’s) equator. Earth rotational pole is tilted 23.4 degrees in relation to the plane of its orbit (known as the ecliptic), and the Moon’s orbit is set at an inclination of 5.1 degrees relative to the ecliptic. In this sense, the Earth-Moon system behaves like a binary planet, revolving around a fixed barycenter.

The two points where the Moon’s path intersects the ecliptic are known as the ascending and descending nodes. These move around the ecliptic as well, lining up (known as a syzygy) during two seasons a year to cause lunar and solar eclipses.

The complex motion of the Moon, depicting the precession of the nodes versus the average movement of the line of apsides. (Credit: Geologician, Homunculus 2. Wikimedia Commons graphic under a Creative Common Attribution 3.0 Unported license).
The complex motion of the Moon, depicting the movement of the nodes versus the average movement of the line of apsides. (Credit: Geologician, Homunculus 2. Wikimedia Commons graphic under a Creative Common Attribution 3.0 Unported license).

But our friend the line of apsides is being dragged backwards relative to the motion of the nodes, largely by the influence of our Sun. Not only does this cause the supermoons to shift through the calendar, but the Moon can also ride ‘high’ with a declination of around +/-28 degrees relative to the celestial equator once every 19 years, as happened in 2006 and will occur again in 2025.

Falling only two days after the solstice, this month’s supermoon is also near where the Sun will be in December and thus will also be the most southerly Full Moon of 2013. Visually, the Full Moon only varies 14% in apparent diameter from 34.1’ (perigee) to 29.3’ (apogee).

Can you see the difference? A side by side comparison of the perigee and apogee Moon. (Credit: Inconstant Moon).
Can you see the difference? A side by side comparison of the perigee and apogee Moon. (Credit: Inconstant Moon).

A fun experiment is to photograph the perigee Moon this month and then take an image with the same setup six months later when the Full Moon is near apogee. Another feat of visual athletics would be to attempt to visually judge the Full Moons throughout a given year. Which one do you think is largest & smallest? Can you discern the difference with the naked eye? Of course, you’d also have to somehow manage to insulate yourself from all the supermoon hype!

A comparison of the rising Moon (left) & the Full Moon high in the sky... as you can see, atmospheric refraction actually tends to "shrink" the apparent size of a rising Moon! (Credit:
A comparison of the rising Moon (left) & the Full Moon high in the sky… as you can see, atmospheric refraction actually tends to “shrink” the apparent size of a rising Moon! (Credit & Copyright: Richard Fleet (@dewbow) The Moon Illusion). 

Many folks also fall prey to the rising “Moon Illusion.” The Moon isn’t visually any bigger on the horizon than overhead. In fact, you’re about one Earth radii closer to the Moon when it’s at the zenith than on the horizon. This phenomenon is a psychological variant of the Ponzo illusion.

The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Note the size difference. Image Credit: Marco Langbroek, the Netherlands, via Wikimedia Commons.
The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Note the size difference. Image Credit: Marco Langbroek, the Netherlands, via Wikimedia Commons.

Here are some of the things that even a supermoon can’t do, but we’ve actually heard claims for:

–      Be physically larger. You’re just seeing the regular-sized Moon, a tiny bit closer.

–      Cause Earthquakes. Yes, we can expect higher-than-normal Proxigean ocean tides, and there are measurable land tides that are influenced by the Moon, but no discernible link between the Moon and earthquakes exists. And yes, we know of the 2003 Taiwanese study that suggested a weak statistical correlation. And predicting an Earthquake after it has occurred, (as happened after the 2011 New Zealand quake) isn’t really forecasting, but a skeptical fallacy known as retrofitting.

–      Influence human behavior. Well, maybe the 2013 Full Moon will make some deep sky imagers pack it in on Sunday night. Lunar lore is full of such anecdotes as more babies are born on Full Moon nights, crime increases, etc. This is an example the gambler’s fallacy, a matter of counting the hits but not the misses. There’s even an old wives tale that pregnancy can be induced by sleeping in the light of a Full Moon. Yes, we too can think of more likely explanations…

–      Spark a zombie apocalypse. Any would-be zombies sighted (Rob Zombie included) during the supermoon are merely coincidental.

Do get out and enjoy the extra illumination provided by this and any other Full Moon, super or otherwise. Also, be thankful that we’ve got a large nearby satellite to give our species a great lesson in celestial mechanics 101!

Posted on by David Dickinson

Catch the Moon pairing with Mercury & Venus Tonight

Looking west at sunset from latitude 30 degrees north. The ecliptic and Mercury's orbit along with a 10 degree field of view outlined for reference. All graphics created by the author using Starry Night).

If you’ve never seen Mercury, this week is a great time to try.

Over the past few weeks, observers worldwide have been following the outstanding tight triple conjunction of Mercury, Venus and Jupiter low to the west at dusk.

Jupiter has exited the evening sky, headed for conjunction with the Sun on June 19th. I caught what was probably our last glimpse of Jupiter for the season clinging to the murky horizon through binoculars just last week. If you’re “Jonesin’ for Jove,” you can follow its progress this week through superior conjunction as it transits the Solar Heliospheric Observatory’s LASCO C3 camera.

This leaves the two innermost worlds of our fair solar system visible low to the west at dusk. And tonight, they’re joined by a very slender waxing crescent Moon, just over two days after New phase.

The Moon, Venus and Mercury as seen from 30 degrees north tonight at 9PM EDT.
The Moon, Venus and Mercury as seen from 30 degrees north tonight at 9PM EDT.

The evening of June 10th finds a 4% illuminated Moon passing just over 5 degrees (about 10 Full Moon diameters) south of Venus and Mercury. Venus will be the first to appear as the sky darkens, shining at magnitude -3.9 and Mercury will shine about 40 times fainter above it at magnitude +0.3.

Ashen light, also known as Earthshine will also be apparent on the darkened limb of the Moon. Another old-time term for this phenomenon is “the Old Moon in the New Moon’s Arms.” Ashen light is caused by sunlight being reflected off of the Earth and illuminating the nighttime Earthward facing portion of the Moon. Just how prominent this effect appears can vary depending on the total amount of cloud cover on the Earth’s Moonward facing side.

....and the orientation of the Moon, Mercury and Venus on the night of June 12th and ~9PM EDT.
….and the orientation of the Moon, Mercury and Venus on the night of June 12th and ~9PM EDT.

This week sets the stage for the best dusk apparition of Mercury for northern hemisphere viewers in 2013. Orbiting the Sun every 88 Earth days, we see Mercury either favorably placed east of the Sun in the dusk sky or west of the Sun in the dawn sky roughly six times a year. Mercury’s orbit is markedly elliptical, and thus not all apparitions are created the same. An elongation near perihelion, when Mercury is 46 million kilometers from the Sun, can mean its only 17.9 degrees away from the Sun as viewed from the Earth. An elongation near aphelion, 69.8 million kilometers distant, has a maximum angular separation of 27.8 degrees.

This week’s greatest elongation of 24.3 degrees occurs on June 12th. It’s not the most extreme value for 2013, but does have another factor going for it; the angle of the ecliptic. As we approach the solstice of June 21st, the plane of the solar system as traced out by the orbit of the Earth is at a favorable angle relative to the horizon. Thus, an observer from 35 degrees north latitude sees Mercury 18.4 degrees above the horizon at sunset, while an observer at a similar latitude in the southern hemisphere only sees it slightly lower at 16.9 degrees.

Venus and the Moon make great guides to locate Mercury over the next few nights. It’s said that Copernicus himself never saw Mercury with his own eyes, though this oft repeated tale is probably apocryphal.

We also get a shot at a skewed “emoticon conjunction” tonight, not quite a “smiley face” (: as occurred between Jupiter, Venus and the Moon in 2008, but more of a “? :” Stick around until February 13th, 2056 and you’ll see a much tighter version of the same thing! A time exposure of a pass of the International Space Station placed near Mercury and Venus could result in a planetary “meh” conjunction akin to a “/:” Hey, just throwing that obscure challenge out there. Sure, there’s no scientific value to such alignments, except as testimony that the universe may just have a skewed sense of humor…

Through the telescope, Venus currently shows a 10” diameter gibbous phase, while Mercury is only slightly smaller at 8” and is just under half illuminated. No detail can be discerned on either world, as a backyard telescope will give you the same blank view of both worlds that vexed astronomers for centuries. These worlds had to await the dawn of the space age to give up their secrets. NASA’s MESSENGER spacecraft entered a permanent orbit around Mercury in 2011, and continues to return some outstanding science.

Both planets are catching up to us from the far side of their orbits. Mercury will pass within 2 degrees of Venus on June 20th, making for a fine wide field view in binoculars.

And now for the wow factor of what you’re seeing tonight. The Moon just passed apogee on June 9th and is currently about 416,500 kilometers or just over one light second distant. Mercury meanwhile, is 0.86 astronomical units (A.U.), or almost 133 million kilometers, or about 7 light minutes away. Finally, Venus is currently farther away from the Earth than the Sun at 1.59 A.U.s, or about 13.7 light minutes distant.

All this makes for a great show in the dusk skies this week. And yes, lunar apogee just after New sets us up for the closest Full Moon of 2013 (aka the internet sensation known as the “Super Moon”) on June 23rd. More to come on that soon!