Sunday Night: Getting Ready For a ‘Super-Harvest-Blood-Moon Total Lunar Eclipse’

So, heard the one about this weekend’s impending ‘Super-Harvest-Blood-Moon eclipse?’ Yeah, us too. Have no fear; fortunately for humanity, the total lunar eclipse transpiring on Sunday night/Monday morning is a harbinger of nothing more than a fine celestial spectacle, clear skies willing.

This final eclipse of the ongoing lunar tetrad has some noteworthy events worth exploring in terms of science and lore.

The Supermoon Total Lunar Eclipse of September 27-28 2015 from Michael Zeiler on Vimeo.

The Specifics: First, you almost couldn’t ask for better timing. This weekend’s total lunar eclipse occurs during prime time Sunday night for North and South America, and early Monday morning for Europe, Africa and most of the Middle East. This means the Atlantic Region and surrounding areas will see totality in its entirety. This eclipse occurs very near the northward equinoctial point occupied by the Sun during the Northern Hemisphere Spring equinox in March. The date says it all: this eclipse coincides with the Harvest Moon for 2015, falling just under five days after the September equinox.

Early cloud cover prospects for Sunday night over the contiguous United States. Image credit: The National Weather Service
Early cloud cover prospects for Sunday night over the contiguous United States. Image credit: The National Weather Service

For saros buffs, Sunday’s eclipse is part of lunar saros series 137, member 28 of 81. This saros started back in 1564 and produced its first total lunar eclipse just two cycles ago on September 6th 1979. Saros 137 runs all the way out to its final eclipse on April 20th, 2953 AD.  

And yes, this upcoming total lunar eclipse occurs very near the closest lunar perigee for 2015. How rare are ‘Supermoon’ lunar eclipses? Well, we took a look at the phenomenon, and found 15 total lunar eclipses occurring near lunar perigee for the current century:

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Perigee eclipses for the 21st century. To make the cut, a total lunar eclipse needed to occur within 24 hours of lunar perigee.  Image credit: Dave Dickinson

You’ll note that four saroses (the plural of saros) are producing perigee or ‘Proxigean’ total lunar eclipses during this century, including saros 137.

Does the perigee Moon effect the length of totality? It’s an interesting question. Several factors come into play that are worth considering for Sunday night’s eclipse. First, the Moon moves a bit faster near perigee as per Kepler’s second law of motion. Second, the Moon is a shade larger in apparent size, 34’ versus 29’ near apogee. Lastly, the conic section of the Earth’s shadow or umbra is a bit larger closer in; you can fit three Moons side-by-side across the umbra around 400,000 kilometers out from the Earth. Sunday night’s perigee occurs 65 minutes after Full Moon at 2:52 UT/10:52 PM EDT. Perigee Sunday night is 356,876 kilometers distant, the closest for 2015 by just 115 kilometers, and just under 500 kilometers short of the closest perigee that can occur. This is, however, the closest perigee time-wise to lunar totality for the 21st century; you have to go all the way back to 1897 to find one closer, at just four minutes apart.

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An 1888 depiction of a total lunar eclipse. Image credit: E. Weib, Bilderatlas de Sternenwelt

Now, THAT was and eclipse!

This all culminates in a period for totality on Sunday night of just under 72 minutes in duration, 35 minutes shy of the maximum possible for a central total lunar eclipse. An eclipse won’t top this weekend’s in terms of duration until January 31st 2018.

 

Here are the key times to watch for on Sunday night:

Penumbral phase begins: 00:12 UT/8:12 PM EDT (on the 27th)

Partial phase begins: 1:07 UT/9:07 PM EDT

Totality begins: 2:11 UT/10:11 PM EDT

Totality ends: 3:23 UT/11:23 PM EDT

Partial phase ends: 4:27 UT/00:27 AM EDT

Penumbral phase ends: 5:22 UT/1:22 AM EDT

Note that one 18 year 11 day and 8 hour saros period later, saros 137 will again produce a perigee eclipse nearly as close as this weekend’s on October 8th, 2033.

The classic hallmark of any total lunar eclipse is the reddening of the Moon. You’re seeing the combination of all the world’s sunsets, refracted into the inky umbra of the Earth and cast upon the surface of the Moon. To date, no human has stood upon the surface of the Moon and gazed upon the spectacle of a solar eclipse caused by the Earth.

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The orientation of the Sun and Earth as seen from the Moon during Sunday night’s eclipse. Image credit: Stellarium

Not all eclipses are created equal when it comes to hue and color. The amount of dust and aerosols suspended in the atmosphere can conspire to produce anything from a bright, yellowish-orange tint, to a brick dark eclipse where the Moon almost disappears from view entirely. The recent rapid fire tetrad of four eclipses in 18 months has provided a good study in eclipse color intensity. The deeper the Moon dips into the Earth’s shadow, the darker it will appear… last April’s lunar eclipse was just barely inside the umbra, making many observers question if the eclipse was in fact total at all.

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Refraction of sunlight during a total lunar eclipse. Image credit: Raycluster/Public Domain

We the describe color of the eclipsed Moon in terms of its number on the Danjon scale, and recent volcanic activity worldwide suggests that we may be in for a darker than normal eclipse… but we could always be in for a surprise!

Old time mariners including James Cook and Christopher Columbus used positional measurements of the eclipsed Moon at sea versus predictions published in almanac tables for land-based observatories to get a one-time fix on their longitude, a fun experiment to try to replicate today. Kris Columbus also wasn’t above using beforehand knowledge of an impending lunar eclipse to help get his crew out of a tight jam.

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A long timelapse of totality during a 2003 total lunar eclipse, back from the glorious days of film. Image credit: Dave Dickinson

And speaking of the next perigee Moon total lunar eclipse for saros 137 on October 8th, 2033…  if you catch that one, this weekend’s, and saw the September 16th, 1997 lunar eclipse which spanned the Indian Ocean region, you’ll have completed an exeligmos, or a triple saros of eclipses in the same series 54 years and 33 days in length, an exclusive club among eclipse watchers and a great word to land on a triple letter word score in Scrabble…

Exeligmos is also the title of one of our original scifi tales involving eclipses, along with Shadowfall.

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The 2010 winter solstice eclipse. Image credit: Dave Dickinson

Here’s another neat challenge: the International Space Station makes two shadow passes during the lunar eclipse over the contiguous United States. The first one occurs during totality, and spans from eastern Louisiana to central Maine from 2:14 to 2:20 UT; the second pass occurs during the final partial phases of the eclipse spanning from southern Arizona to Lake Superior from 3:47 to 3:54 UT. These are un-illuminated shadow passes of the ISS. Observers have captured transits of the ISS during a partial solar eclipse, but to our knowledge, no one has ever caught a transit of the ISS during a total lunar eclipse; ISS astros should also briefly be able to spy the eclipsed Moon from their orbital vantage point. CALSky will have refined passage times about 48 hours prior to Sunday.

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Projections for ISS shadow passes across the Moon during Sunday night’s eclipse. The first path occurs during totality, and the second during the final partial phases of the eclipse. Image credit: Dave Dickinson/calculations from CALSky

Clouded out? Live on the wrong side of the planet? The good folks at the Virtual Telescope Project have got you covered, with a live webcast of the total lunar eclipse starting at 1:00 UT/9:00 PM EDT.

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Image credit: The Virtual Telescope Project

And as the eclipse draws to an end, the question of the hour always is: when’s the next one? Well, the next lunar eclipse is a dim penumbral on March 23rd, 2016, which follows a total solar eclipse for southeastern Asia on March 9th, 2016… but the next total lunar won’t occur until January 31st, 2018, which also happens to be the second Full Moon of the month… a ‘Blue Blood Moon Eclipse?’

Sorry, we had to go there. Hey, we could make the case for Sunday’s eclipse also occurring on World Rabies Day, but perhaps a ‘Rabies Eclipse’ just doesn’t have the SEO traction. Don’t fear the Blood Moon, but do get out and watch the final lunar eclipse of 2015 on Sunday night!

Was This Past Weekend’s Lunar Eclipse Really Total?

Millions of viewers across the western United States and across the Pacific, to include Australia and New Zealand were treated to a fine Easter weekend lunar eclipse on Saturday. And while this was the third of the ongoing tetrad of four lunar eclipses, it was definitely worth getting up early for and witnessing firsthand.

But was it truly total at all?

To Recap: The April 4th eclipse featured the shortest advertised duration for totality for the 21st century, clocking in at just four minutes and 43 seconds in length. In fact, you’d have to go all the way back to 1529 to find a shorter span of totality, at one minute and 42 seconds. And you’ll have to wait until September 11th, 2155 to find one that tops it in terms of brevity.

The April 4th lunar eclipse over the Las Vegas strip. Image credit and copyright: John Lybrand
The April 4th lunar eclipse over the Las Vegas strip. Image credit and copyright: John Lybrand

We wrote recently about the saros cycle, and how this past weekend’s eclipse was the first in lunar saros series 132 to feature totality.

A fascinating discussion as to whether this was a de facto total lunar eclipse has recently sprung up on the message boards and a recent Sky and Telescope article online.

The geometry that creates a total lunar eclipse. Credit: NASA
The geometry that creates a total lunar eclipse. Credit: NASA

It all has to do with how you gauge the shape and size of the Earth’s shadow.

This is a surprisingly complex affair, as the Earth’s atmosphere gives the umbra a ragged and indistinct edge. If you’ve ever taken our challenge to determine your longitude using a lunar eclipse — just as mariners such as Christopher Columbus did while at sea — then you know how tough it is to get precise contact timings. There has been an ongoing effort over the years to model the size changes in Earth’s shadow using crater contact times during a lunar eclipse.

Many observers have commented in forums and social media that the northern limb of the Moon stayed pretty bright throughout the brief stretch of totality for Saturday’s eclipse.

What happens (in the skies over) Vegas... the lunar eclipse captured from the Luxor Hotel. Image credit and copyright: Rob Sparks
What happens (in the skies over) Vegas… the lunar eclipse captured from the Luxor Hotel. Image credit and copyright: Rob Sparks

“There are 3 ways of computing the magnitude of a lunar eclipse,” Eclipse expert David Herald mentioned in a recent Solar Eclipse Message List (SEML) posting:

The ‘traditional’ way as used in the Astronomical Almanac is attributed to Chauvenet – where the umbral radius is increased by a simple 2% – with the radius being based on the Earth’s radius at 45 deg latitude (and otherwise the oblateness of the Earth is ignored). For this eclipse the Chauvenet magnitude was 1.005.

 The second way (used in the French Almanac, and more recently by Espenak & Meeus in their ‘Five Millennium Canon of Lunar Eclipses’ is the Danjon method. It similarly uses the Earth’s radius at 45 deg (and otherwise the oblateness is ignored), and increases the Earth’s radius by 75km. For this eclipse the Danjon magnitude is 1.001

The most recent approach (Herald & Sinnott JBAA 124-5 pgs 247-253, 2014) is based on the Danjon approach; however it treats the Earth as oblate, allows for the varying inclination of the Earth relative to the Sun during the year, and increases the Earth’s radius by 87km – being the best fit to 22,539 observations made between 1842 and 2011. For this eclipse the magnitude is computed as 1.002.

“As for eclipses, to me it is total when sliver of light comes through the edge of the Earth’s profile,” eclipse chaser Patrick Poitevin told Universe Today. “Once a minimum of light passes through any of the lunar dales (as it does during a total solar eclipse) I do not concede it as a total. Same for a lunar eclipse.”

A partial phase for the April 4th lunar eclipse above a silo. Image credit and copyright: Brian who is called Brian
A partial phase for the April 4th lunar eclipse above a silo. Image credit and copyright: Brian who is called Brian

Michael Zeiler at the Great American Eclipse also had this to say to Universe Today about the subject:

This is a complex question because the shape of the Earth’s umbra upon the Moon is diffuse due to the effects of the Earth’s atmosphere. The various models used (with corrected radii for the Earth) are empirically based on crater timings of past lunar eclipses, of which there is some uncertainty. I’m sure this accounted for the difference between the USNO duration of eclipse and NASA.

The comment (in the recent Sky & Telescope post online) by Curt Renz is valid; correcting for the Earth’s flattening (meaning that the Earth’s radius from pole to pole is about a third of a percent shorter than the radius across the equator) might influence whether this very low magnitude eclipse is total or not. I haven’t made the calculation whether the Earth’s flattening tips this eclipse from total to partial, but it’s plausible.

Totality! Image credit and copyright: Rolf Wahl Olsen
Totality! Image credit and copyright: Rolf Wahl Olsen

 There is another wrinkle: due to parallactic shifts of the Moon when observing from either pole of the Earth, it might be that for a lunar eclipse right on the knife edge of total/partial, that it may indeed be total from one polar region and partial from another. This is a kind of libration, but it would be a very subtle difference and probably unobservable. 

 It is only possible to conclusively define Saturday’s eclipse as total or partial if you define a brightness threshold for the Sun’s photosphere illuminating an edge of the Moon. The problem here is that this line is indistinct and fuzzy. I watched the lunar eclipse carefully with this question in mind and I could not decide for myself whether this lunar eclipse was total or partial. I think it would require a photometer to make this distinction.

 Certainly, there’s little record of just how the 102 second long lunar eclipse of 1529 appeared. Ironically, it too was a total eclipse near sunrise as seen from Europe. On the other side of the coin, the deep partial eclipse of August 26th, 1961 just missed totality at 98.6% obscuration… and the two lunar eclipses in 2021 have similar circumstances, with a barely total lunar eclipse just 15 minutes long on May 26th and a 97.4% partial lunar eclipse on November 19th.

The circumstances for the 1529 total solar eclipse. Image credit: F.Espenak/NASA/GSFC
The circumstances for the 1529 total solar eclipse. Image credit: F.Espenak/NASA/GSFC

So maybe we won’t have to wait until 2155 to see another brief lunar eclipse that blurs the lines and refuses to play by the rules.

The eclipse as seen from Coral Towers Observatory. Image credit and copyright: Joseph Brimacombe
The eclipse as seen from Coral Towers Observatory. Image credit and copyright: Joseph Brimacombe

What do you, the readers think? What did you see last Saturday morn, a bright total lunar eclipse, or a deep partial?

Predicting Eclipses: How Does the Saros Cycle Work?

Boy, how about that total solar eclipse last Friday? And there’s more in store, as most of North America will be treated to yet another total lunar eclipse on the morning of April 4th. This eclipse is member three of four of a quartet of lunar eclipses, known as a tetrad.

Solar and lunar eclipses are predictable, and serve as a dramatic reminder of the clockwork nature of the universe. Many will marvel at the ‘perfect symmetry’ of eclipses as seen from the Earth, though the true picture is much more complex. Yes, the Sun is roughly 400 times larger in diameter than the Moon, but also about 400 times farther away. This distance isn’t always constant, however, as the orbits of both the Earth and Moon are elliptical. And to complicate matters, the Moon is currently moving 3 to 4 centimetres farther away from the Earth per year. Already, annular eclipses are more common in the current epoch than are total solar eclipses, and about 1.4 billion years from now, total solar eclipses will cease to happen entirely.

This has an impact on lunar eclipses as well. The dark inner umbra of the Earth is an average of about 1.25 degrees across at the distance from Earth to the Moon. The Moon’s orbit is inclined 5.1 degrees relative to the ecliptic plane, which traces out the Earth’s path around the Sun.  If this inclination was equal to zero, we’d be treated to two eclipses — one solar and one lunar — every 29.5 day synodic month.

This inclination assures that we have, on average, two eclipse seasons year, and that eclipses occur in groupings of 2-3.  The maximum number of eclipses that can occur in a calendar year is 7, which next occurs in 2038, and the minimum is 4, as occurs in 2015.

A solar eclipse occurs at New Moon, and a lunar eclipse always occurs at Full — a fact that many works of film and fiction famously get wrong. And while you have to happen to be in the narrow path of a solar eclipse to witness totality, the whole Moonward facing hemisphere of the Earth gets to witness a lunar eclipse. Ancient cultures recognized the mathematical vagaries of the lunar and solar cycles as they attempted to reconcile early calendars. Our modern Gregorian calendar strikes a balance between the solar mean and tropical year. The Muslim calendar uses strictly lunar periods, and thus falls 11 days short of a 365 day year. The Jewish and Chinese calendars incorporate a hybrid luni-solar system, assuring that an intercalculary ‘leap month’ needs to be added every few years.

But trace out the solar and lunar cycles far enough, and something neat happens. Meton of Athens discovered in the 5th century BC that 235 synodic periods very nearly equals 19 solar years to within a few hours. This means that the phases of the Moon ‘sync up’ every 19-year Metonic cycle, handy if you’re say, trying to calculate the future dates for a movable feast such as Easter, which falls on (deep breath) the first Sunday after the first Full Moon after the March equinox.

Credit
A unique ‘moondial’ in front of the Flandrau observatory on the University of Arizona Tucson campus. Image credit: David Dickinson

But there’s more. Take a period of 223 synodic months, and they sync up three key lunar cycles which are crucial to predicting eclipses;

Synodic month- The time it takes for the Moon to return to like phase (29.5 days).

Anomalistic month- The time it takes for the Moon to return to perigee (27.6 days).

Draconic month- the time it takes for the Moon to return to a similar intersecting node (ascending or descending) along the ecliptic (27.2 days).

That last one is crucial, as eclipses always occur when the Moon is near a node. For example, the Moon crosses ascending node less than six hours prior to the start of the April 4th lunar eclipse.

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The evolution of a solar saros. Image credit: A.T. Sinclair/NASA/GSFC/Wikimedia Commons

And thus, the saros was born. A saros period is just eight hours shy of 18 years and 11 days, which in turn is equal to 223 synodic, 242 anomalistic or 239 draconic months.

The name saros was first described by Edmond Halley in 1691, who took it from a translation of an 11th century Byzantine dictionary. The plural of saros is saroses.

This also means that solar and lunar eclipses one saros period apart share nearly the same geometry, shifted 120 degrees in longitude westward. For example, the April 4th lunar eclipse is member number 30 in a cycle of 71 lunar eclipses belonging to saros series 132. A similar eclipse occurred one saros ago on March 24th, 1997. Stick around until April 14th, 2033 and you’ll complete a personal triple saros of eclipses, known as an exeligmos.

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A tale of three eclipses spanning 1997-2033 from lunar saros 132. Credit: Fred Espenak/NASA/GSFC

Dozens of saros series — both solar and lunar — are underway at any particular time.

But there’s something else unique about April’s eclipse. Though saros 132 started with a slim shallow penumbral eclipse way back on May 12th, 1492, this upcoming eclipse features the very first total lunar eclipse of the series. You can tell, as the duration of totality is a short 4 minutes and 43 seconds, a far cry from the maximum duration of 107 minutes that can occur during a central eclipse.

Created by author.
The evolution of lunar saros 132, showing five key eclipses out of the 71 in the series. Created by author

This particular saros cycle of eclipses will continue to become more central as time goes on. The final total lunar eclipse of the series occurs on August 2nd, 2213 AD, and the saros finally ends way out on June 26th, 2754.

Eclipses, both lunar and solar, have also made their way into the annuals of history. A rising partial eclipse greeted the defenders of Constantinople in 1453, fulfilling a prophecy in the mind of the superstitious when the city fell to the Ottoman Turks seven days later. And you’d think we’d know better by now, but modern day fears of the ‘Blood Moon‘ seen during an eclipse still swirl around the internet even today. Lunar eclipses even helped mariners get a onetime fix on longitude at sea: Christopher Columbus and Captain James Cook both employed this method.

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The rising partial eclipse as seen from Constantinople on May 22nd 1453. Image credit: Stellarium

All thoughts to ponder as you watch the April 4th total lunar eclipse. This eclipse will be visible for observers across the Pacific, the Asian Far East, Australia and western North America, after which you’ll have one more shot at total lunar eclipse in 2015 on September 28th. The next total lunar eclipse after that won’t be until January 31st 2018, favoring North America.

Welcome to the saros!

Read Dave Dickinson’s eclipse-fueled sci-fi tales Exeligmos and Shadowfall.

REAL Images of Eclipses Seen From Space

That ‘amazing astro-shot that isn’t’ is making the rounds of ‘ye ole web again.

You know the one. “See an Amazing Image of an Eclipse… From SPACE!!!” screams the breathless headline, with the all-too-perfect image of totality over the limb of the Earth, with the Milky Way thrown in behind it for good measure.

As the old saying goes, if it looks too good to be true, it probably is. Sure, the pic is a fake, and it’s been debunked many, many times since it was first released into the wild a few years back. But never let reality get in the way of a good viral meme. As eclipse season 2 of 2 gets underway tonight with a total lunar eclipse followed by a partial solar eclipse on October 23rd both visible from North America, the image is once again making its rounds. But there’s a long history of authentic captures of eclipses from space that are just as compelling. We’ve compiled just such a roll call of real images of eclipses seen from space:

SDO
A partial solar eclipse as captured by SDO. Credit: NASA/SDO.

The Solar Dynamics Observatory:

Launched in 2010, The Solar Dynamics Observatory or SDO is NASA’s premier orbiting solar observatory. But unlike Sun-staring satellites based in low Earth orbit, SDO’s geosynchronous orbit assures that it tends to see a cycle of partial solar eclipses twice a year, roughly around the equinoxes. And like many satellites, SDO also passes into the Earth’s shadow as well, offering unique views of a solar eclipse by the limb of the Earth from its vantage point.

JAXA
The Moon ‘photobombs’ the view of Hinode. Credit: NASA/JAXA.

Hinode:

A joint mission between NASA and JAXA (the Japanese Aerospace Exploration Agency) launched in 2006, Hinode observes the Sun from low Earth orbit. As a consequence, it nearly has a similar vantage point as terrestrial viewers and frequently nabs passages of the Moon as solar eclipses occur. Such events, however, are fleeting; moving at about eight kilometres per second, such eclipses last only seconds in duration!

ESA
Catching the passage of the Moon during a brief partial eclipse. Credit: ESA.

Proba-2:

Like Hinode, Proba-2 is the European Space Agency’s flagship solar observing spacecraft based in low Earth orbit. It also catches sight of the occasional solar eclipse, and these fleeting passages of the Moon in front of the Earth happen in quick multiple cycles. Recent images from Proba-2 are available online.

Eclipses from the ISS:

The International Space Station isn’t equipped to observe the Sun per se, but astronauts and cosmonauts aboard have managed to catch views of solar eclipses in an unusual way, as the umbra of the Moon crosses the surface of the Earth. Such a view also takes the motion of the ISS in low Earth orbit into account. Cosmonauts aboard the late Mir space station also caught sight of the August 11th, 1999, total solar eclipse over Europe.

NASA GOES
NASA’ s GOES-WEST spies the umbra of the Moon. Credit: NASA-GOES.

NASA-GOES:

Weather satellites can, and do, occasionally catch sight of the inky black dot of the Moon’s penumbra crossing the disk of the Earth.  GOES-West snapped the above image of the November 13th, 2012, solar eclipse. The umbra of the Moon’s shadow races about 1700 kilometres per hour from west to east during an eclipse, and we can expect some interesting images in 2017 when the next total solar eclipse crosses the United States on August 21st, 2017.

NASA
An ‘Apollo eclipse!’ Credit: NASA.

Apollo-Soyuz Test Project:

The final mission of Apollo program, the 1975 Apollo-Soyuz Test Project, also yielded an unusual and little known effort to observe the Sun. The idea was to use the Apollo command module as a “coronagraph” and have cosmonauts image the Sun from the Soyuz as the Apollo spacecraft blocked it out after undocking. Unfortunately, the Apollo thrusters smeared the exposure, and it became a less than iconic— though unusual — view from the space age.

Gemini XII
A partial solar eclipse snapped by the crew of Gemini XII. Credit: NASA.

Gemini XII and the first eclipse seen from space:

On November 12th, 1966, a total solar eclipse graced South America. Astronauts James Lovell Jr. and Edwin “Buzz” Aldrin Jr. were also in orbit at the time, and managed to snap the first image of a solar eclipse from space. Gemini XII was the last flight of the program, and the astronauts initially thought they’d missed the eclipse after a short trajectory burn.

ISS
The 2012 transit of Venus as seen from the ISS. Credit: NASA/Don Pettit.

ISS Astronauts catch a transit of Venus:

We were fortunate that the International Space Station had its very own amateur astronomer in residence in 2012 to witness the historic transit of Venus from space. NASA astronaut Don Pettit knew that the transit would occur during his rotation, and packed a full-aperture white light solar filter for the occasion. Of course, a planetary transit meets the very loosest definition of a partial eclipse, but it’s a unique capture nonetheless.

Kaguya:

Japan’s SELENE-Kaguya spacecraft entered orbit around the Moon in 2007 and provided some outstanding imagery of our solitary natural neighbor. On February 10th, 2009, it also managed to catch a high definition view of the Earth eclipsing the Sun as seen from lunar orbit. A rare catch, such an event occurs during every lunar eclipse as seen from the Earth.

Mars eclipse
Curiosity captures a misshapen eclipse from the surface of Mars. Credit: NASA/JPL.

An unusual eclipse… seen from Mars:

We’re fortunate to live in an epoch in time and space where total solar eclipses can occur as seen from the Earth. But bizarre eclipses and transits can also be seen from Mars. The Spirit and Opportunity rovers have witnessed brief transits of the Martian moons Phobos and Deimos across the face of the Sun, and in 2010, the Curiosity rover recorded the passage of Phobos in front of the Sun in a bizarre-potato shaped “annular eclipse”. But beyond just the “coolness” factor, the event also helped researchers refine our understanding of orbital path of the Martian moon.

The future: It’s also interesting to think of what sort of astronomical wonders await travelers as we venture out across the solar system. For example, no human has yet to stand on the Moon and witness a solar eclipse. Or how about a ring plane passage through Saturn’s rings, thus far only witnessed via the robotic eyes of Cassini? Of course, for the best views of Saturn’s rings, we recommend a vacation stay on Iapetus, the only major Saturnian moon whose orbit is inclined to the ring plane. And stick around ‘til November 10th, 2084, and you can witness a transit of Earth, the Moon and Phobos as seen from the slopes of Elysium Mons on Mars:

Hopefully, they’ll have perfected that whole Futurama “head-in-a-jar” thing by then…

-Looking for eclipses in science fiction? Check out the author’s tales Exeligmos and Shadowfall.

Our Complete Guide to the October 8th “Hunter’s Moon” Total Lunar Eclipse

October 2014 means eclipse season 2 of 2 for the year is upon us.

Don’t fear the ‘Blood Moon’ that’s currently infecting the web, but if you find yourself on the correct moonward facing hemisphere of the planet, do get out and observe the total lunar eclipse coming right up on the morning of Wednesday, October 8th. This is the second and final total lunar eclipse of 2014, and the second of four in a quartet series of lunar eclipses known as a tetrad.

And the good news is, the eclipse once again favors nearly all of North America. From the western U.S. and Canada, the Moon will be high in the western skies when partial phases begin early in the morning on October 8th. The western U.S., Canada and Alaska will see the entire 61 minute span of totality, just 18 minutes shorter than last April’s lunar eclipse. The Moon will be high in the sky during totality for the Hawaiian Islands, and viewers in Australia and the Pacific Far East will witness the eclipse in the evening hours.

Visibility
The visibility regions for the total lunar eclipse. Credit: NASA/GSFC/Espenak.

This lunar eclipse is part of saros 127, and marks number 42 of a series of 72 for that particular saros. If you witnessed the total lunar eclipse visible from North America and Europe on September 27th, 1996, you caught the last of the series, and if you catch the next eclipse in the saros on October 18th, 2032, you’ve earned a veteran lunar eclipse-watchers badge of seeing an exeligmos, or “triple saros” of eclipses.

The path of the Moon through the Earth’s umbra on October 8th. Adapted from NASA/GFSC.

Timings for key phases of the eclipse are as follows:

P1- Penumbral phase begins: 8:14 UT/4:14 EDT/1:14 PDT

U1- Umbral (partial) phase begins: 9:15 UT/5:14 EDT/2:14 PDT

U2- Totality begins: 10:24 UT/6:24 EDT/3:24 PDT

Mid-totality- 10:55 UT/6:55 EDT/3:55 PDT

U3- Totality ends: 11:25 UT/7:25 EDT/4:25 PDT

U4- Umbral phase ends: 12:35 UT/5:35 PDT

P4- Penumbral phase ends: 13:35/6:35 PDT

Not all total lunar eclipses are the same when it comes to color. Totality can appear anywhere from a dark brick color, as happened during the December 9th, 1992, eclipse following the eruption of Mount Pinatubo, when the Moon nearly disappeared during totality, to a bright coppery red, as seen during the April eclipse earlier this year. The Moon passes to the north of the dark central core of the Earth’ shadow next Wednesday, so expect a brighter than normal eclipse, especially along the Moon’s northeast limb. Grab a painter’s wheel and compare the eclipsed Moon to swatches of orange through red: what colors do you see? What you’re seeing is the combinations of all the world’s sunsets refracted into the cone of the Earth’s shadow, which is about three times the size of the Moon at its average distance as seen from Earth. Remember, the Moon is experiencing a total solar eclipse as we watch the lunar eclipse unfold!

Stellarium
The October 8th total solar eclipse as seen from the Apollo 11 landing site on the nearside of the Moon. Created using Stellarium.

This color can be quantified and described on what is known as the Danjon Scale, with 0 being a very dark eclipse with the Moon barely visible, to a 4, meaning a very bright eclipse.

And yes, each total lunar eclipse is now receiving the “Blood Moon” meme thanks to ye ole Internet. Expect the conspiracy-minded to note that this eclipse occurs on the Jewish holiday of Sukkot starting at sundown on the 8th, which isn’t really all that wondrous as the Jewish calendar is a luni-solar one, and total lunar eclipses have to occur during a Full Moon by definition. Wait long enough, and an occasional “Sukkot total lunar eclipse” does indeed occur.

Uranus occultation
The footprint of the October 8th occultation of Uranus by the Moon during totality. (Credit: Occult 4.1.0).

But a truly rare event does occur during this eclipse, as the Moon actually occults (passes in front of) the planet Uranus during totality for observers in northern Alaska and northeast Asia. The rest of us in the observing zone will see a near miss. Can you spy Uranus with binoculars near the lunar limb during totality? Another such rarity occurred during Shakespeare’s time on December 30th, 1591, involving Saturn and the eclipsed Moon, and another such odd occurrence transpires in 2344 A.D.

2344 eclipse
The circumstances of the 2344 eclipse/occultation. Credit: Starry Night, NASA/GSFC & Occult 4.0.1.

The brightest star to be occulted by the total eclipsed Moon as it crosses the constellation Pisces is +7.9th magnitude HIP 4231 for the northern U.S. and Canada.

And speaking of historical eclipses, there’s a Columbus Day tie-in with the phenomenon as well. Like many mariners of his day, Columbus was well-versed in celestial navigation, and used a total lunar eclipse to get a good one-time fix on his longitude at sea, an experiment that you can easily replicate. Columbus also wasn’t above using prior knowledge of an impending lunar eclipse to get himself and his crew out of a bind with the locals when the need arose.

An outstanding sequence of images taken during the April 15th, 2014 total lunar eclipse. Credit: Michael Zeiler (Eclipse-Maps) Used with permission.
An outstanding sequence of images taken during the April 15th, 2014, total lunar eclipse. Credit: Michael Zeiler (Eclipse-Maps) Used with permission.

Photographing an eclipse with a DSLR is as easy as shooting an image of the Moon. Try this a few evenings before the big event. A minimum focal length of 200mm is needed to render the Moon larger than a white dot in the image, and remember that the Moon is much darker during total eclipse, and you’ll need to step the exposure times rapidly down from 1/100th of a second to 2 to 4 seconds during totality.

A long-running effort by Sky & Telescope has been looking for amateur observations of precise crater contacts along the rim of the umbra in an effort to measure variations in the diameter of the Earth’s shadow.

starry night
The Moon versus Uranus as seen from Napa, California just past mid-eclipse on the morning of October 8th. Credit: Starry Night Education Software.

As always, weather prospects are the big question mark when it comes to eclipses. Typically, the southwestern U.S. experiences 13-20 clear days in the month of October; prospects worsen to the northwest, with an average of 3-12 days. We’ll be looking at resources such as NOAA, Skippy Sky and ClearSkyChart on the evenings leading up to the 8th. The great thing about a lunar eclipse is, you don’t need a 100% clear sky to see it: just a clear view of the Moon!

Up for a challenge? We’ve yet to see a capture of a shadow transit of the International Space Station in front of the eclipsed Moon. This time around, such a capture should be possible across southern coastal California and the Baja peninsula just minutes prior to the onset of totality.

Orbitron
A shadow pass of the International Space Station just prior to the onset of totality. Note the position of the Moon. Created using Orbitron.

Another bizarre catch, known as a selenelion — witnessing the end of lunar totality after sunrise — may just be possible across the northeastern U.S. into the Canadian Maritimes as the eclipsed Moon sets during totality. The more elevation you can get the better! This works because the Moon lingers a bit in the large shadow of the Earth, plus atmospheric refraction gives the low altitude Sun and Moon a slight boost.

Clouded out? On the wrong side of the planet? You can watch the eclipse online at the following links:

– Live views courtesy of Gialuca Masi and the Virtual Telescope starting at 10:00 UT on October 8th.

– A live webcast starting at 9:00 UT courtesy of Slooh:

– A Columbia State University broadcast, (time to be determined).

Planning an ad-hoc broadcast? Let us know!

And as the eclipse wraps up, the biggest question is always: When’s the next one? Well, lunar eclipse number three of the four eclipse tetrad occurs next year on April 4th, 2015… but in just two weeks time, the western United States and Canada will also witness a fine partial solar eclipse on Oct 23rd

Stay tuned!

Got images of the total lunar eclipse? Send ‘em in to Universe Today’s Flickr forum!

Interested in eclipse sci-fi? Check out our latest short stories Exeligmos and Shadowfall.

A Triple Occultation Bonanza: A Challenging Series of Occultations This Weekend and More

Got clear skies? This week’s equinox means the return of astronomical Fall for northern hemisphere observers and a slow but steady return of longer nights afterwards. And as the Moon returns to the evening skies, all eyes turn to the astronomical action transpiring low to the southwest at dusk.

Three planets and two “occasional” planets lie along the Moon’s apparent path this coming weekend: Mars, Saturn, Mercury and the tiny worldlets of 4 Vesta and 1 Ceres. Discovered in the early 19th century, Ceres and Vesta enjoyed planetary status initially before being relegated to the realm of the asteroids, only to make a brief comeback in 2006 before once again being purged along with Pluto to dwarf planet status.

Credit: Stellarium.
The Moon approaches Saturn on the evening of September 28th as seen from latitude 30 degrees north. Credit: Stellarium.

On Sunday September 28th, the four day old Moon will actually occult (pass in front of) Saturn, Ceres, and Vesta in quick succession. The Saturn occultation is part of a series of 12 in an ongoing cycle. This particular occultation is best for Hawaiian-based observers on the evening of September 28th. Astute observers will recall that Ceres and Vesta fit in the same 15’ field of view earlier this summer. Both are now over six degrees apart and slowly widening. Unfortunately, there is no location worldwide where it’s possible to see all (or two) of these objects occulted simultaneously. The best spots for catching the occultations of +7.8 magnitude Vesta and +9.0 magnitude Ceres are from the Horn of Africa and just off of the Chilean coast of South America, respectively. The rest of us will see a close but photogenic conjunction of the trio and the Moon. To our knowledge, an occultation of Ceres or Vesta by the dark limb of the Moon has yet to be recorded. Vesta also reaches perihelion this week on September 23rd at 4:00 UT, about 2.2 astronomical units from the Sun and 2.6 A.U.s from Earth.

Credit: Andrew Symes
4 Vesta and 1 Ceres share the same field of view this past summer. Credit: Andrew Symes @FailedProtostar.

The reappearance of the Moon in the evening skies is also a great time to try your hand (or eyes) at the fine visual athletic sport of waxing crescent moon-spotting. The Moon passes New phase marking the start of lunation 1135 on Wednesday, September 24th at 6:12 UT/2:12 AM EDT. First sighting opportunities will occur over the South Pacific on the same evening, with worldwide opportunities to spy the razor-thin Moon low to the west the following night. Aim your binoculars at the Moon and sweep about three degrees to the south, and you’ll spy Mercury and the bright star Spica just over a degree apart.

This week’s New Moon is also notable for marking the celebration of Rosh Hashanah, and the beginning of the Jewish year 5775 A.M. at sundown on Wednesday. The Jewish calendar is a hybrid luni-solar one, and inserted an embolismic or intercalculary month earlier this spring to stay in sync with the solar year.

Occult 4.0
The occultation footprint of Saturn. The dashed line denotes where the event occurs in the daytime, while the solid line marks where it can be seen after sunset. Created using Occult 4.1.0.

The Moon also visits Mars and Antares on September 29th. The ruddy pair sits just three degrees apart on the 28th, making an interesting study in contrast. Which one looks “redder” to you? Antares was actually named by the Greeks to refer to it as the “equal to,” “pseudo,” or “anti-Mars…” Mars can take on anything from a yellowish to pumpkin orange appearance, depending on the current amount of dust suspended in its atmosphere. The action around Mars is also heating up, as NASA’s MAVEN spacecraft just arrived in orbit around the Red Planet and India’s Mars Orbiter is set to join it this week… and all as Comet A1 Siding Spring makes a close pass on October 19th!

And speaking of spacecraft, another news maker is photo-bombing the dusk scene, although of course it’s much too faint to see. NASA’s Dawn mission is en route to enter orbit around Ceres in early 2015, and currently lies near R.A. 15h 02’ and declination -14 37’, just over a degree from Ceres as seen from Earth. The Moon will briefly “occult” the Dawn spacecraft as well on September 28th.

Credit: Starry Night
Crowded skies: the Moon approaching Saturn, 4 Vesta, 1 Ceres and the Dawn spacecraft on the 28th. The red arrow shows the direction of the Moon. Created using Starry Night Education Software.

Be sure to keep an eye out for Earthshine on the dark limb of the Moon as our natural neighbor in space waxes from crescent to First Quarter. What you’re seeing is the reflection of sunlight from the gibbous Earth illuminating the lunar plains on the nighttime side of the Moon. This effect gives the Moon a dramatic 3D appearance and can vary depending on the amount of cloud and snow cover currently facing the Moon.

Such a close trio of conjunctions raises the question: when was the last time the Moon covered two or more planets at once? Well, on April 23rd 1998, the Moon actually occulted Venus and Jupiter at the same time, although you had to journey to Ascension Island to witness it!

Credit: Stellarium
The waning crescent Moon approaches Jupiter and Venus on April 23rd, 1998. Credit: Stellarium.

Such bizarre conjunctions are extremely rare. You need a close pairing of less than half a degree for two bright objects to be covered by the Moon at the same time. And often, such conjunctions occur too close to the Sun for observation. A great consequence of such passages, however, is that it can result in a “smiley-face” conjunction, such as the one that occurs on October 15th, 2036:

Credit: Starry Night.
Smile: A close pass of the Moon, Saturn, and Regulus in 2036. Credit: Stellarium.

Such an occurrence lends credence to a certain sense of cosmic irony in the universe.

And be sure to keep an eye on the Moon, as eclipse season 2 of 2 for 2014 kicks off next week, with the second total lunar eclipse of the year visible from North America.

More to come!

The Science Behind the “Blood Moon Tetrad” and Why Lunar Eclipses Don’t Mean the End of the World

 By now, you may have already heard the latest tale of gloom and doom surrounding the upcoming series of lunar eclipses.

This latest “End of the World of the Week” comes to us in what’s being termed as a “Blood Moon,” and it’s an internet meme that’s elicited enough questions from friends, family and random people on Twitter that it merits addressing from an astronomical perspective.

Like the hysteria surrounding the supposed Mayan prophecy back in 2012 and Comet ISON last year, the purveyors of Blood Moon lunacy offer a pretty mixed and often contradictory bag when it comes down to actually what will occur.

But just like during the Mayan apocalypse nonsense, you didn’t have to tally up just how many Piktuns are in a Baktun to smell a rat. December 21st 2012 came and went, the galactic core roughly aligned with the solstice — just like it does every year — and the end of the world types slithered back into their holes to look for something else produce more dubious YouTube videos about.

Here’s the gist of what’s got some folks wound up about the upcoming cycle of eclipses. The April 15th total lunar eclipse is the first in series of four total eclipses spanning back-to-back years, known as a tetrad. There are eight tetrads in the 21st century: if you observed the set total lunar eclipses back in 2003 and 2004, you saw the first tetrad of the 21st century.

The eclipses in this particular tetrad, however, coincide with the Full Moon marking Passover on April 15th and April 4th and the Jewish observance of Sukkot on October 8th and September 28th. Many then go on to cite the cryptic biblical verse from Revelation 6:12, which states;

“I watched as he opened the sixth seal. There was a great earthquake. The Sun turned black like sackcloth made of goat hair. The whole Moon turned blood red.”

Whoa, some scary allegory, indeed… but does this mean the end of the world is nigh?

I wouldn’t charge that credit card through the roof just yet.

First off, looking at the eclipse tetrads for the 21st century, we see that they’re not really all that rare:

21st century eclipse tetrads:

Eclipse #1 Eclipse #2 Eclipse #3 Eclipse #4
May 16th, 2003 November 9th, 2003 May 4th , 2004 October 28th, 2004
April 15th, 2014*+ October 8th, 2014 April  4th, 2015*+ September 28th, 2015
April 25th, 2032 October 18th, 2032 April 14th, 2033*+ October 8th, 2033
March 25th, 2043* September 19th, 2043 March 13th, 2044 September 7th, 2044
May 6th, 2050 October 30th, 2050 April 26th, 2051 October 19th, 2051
April  4th, 2061*+ September 29th, 2061 March 25th, 2062* September  18th, 2062
March 4th, 2072 August 28th, 2072 February 22nd, 2073 August 17th, 2073
March 15th, 2090 September 8th, 2090 March 5th, 2091 August 29th, 2091
*Paschal Full Moon
+Eclipse coincides with Passover

 

Furthermore, Passover is always marked by a Full Moon, and a lunar eclipse always coincides with a Full Moon by definition, meaning it cannot occur at any other phase. The Jewish calendar is a luni-solar based calendar that attempts to mark the passage of astronomical time via the apparent course that the Sun and the Moon tracks through the sky. The Muslim calendar is an example of a strictly lunar calendar, and our western Gregorian calendar is an example of a straight up solar one. The Full Moon marking Passover often, though not always, coincides with the Paschal Moon heralding Easter. And for that matter, Passover actually starts at sunset the evening prior in 2014 on April 14th. Easter is reckoned as the Sunday after the Full Moon falling after March 21st which is the date the Catholic Church fixes as the vernal equinox, though in this current decade, it falls on March 20th. Easter can therefore fall anywhere from March 22nd to April 25th, and in 2014 falls on the late-ish side, on April 20th.

To achieve synchrony, the Jewish calendar must add what’s known as embolismic or intercalculary months (a second month of Adar) every few years, which in fact it did just last month. Eclipses happen, and sometimes they occur on Passover. It’s rare that they pop up on tetrad cycles, yes, but it’s at best a mathematical curiosity that is a result of our attempt to keep our various calendrical systems in sync with the heavens.  It’s interesting to check out the tally of total eclipses versus tetrads over a two millennium span:

Century Number of Total Lunar Eclipses Number of Tetrads Century Number of Total Lunar Eclipses Number of Tetrads
11th

62

0

21st

85

8

12th

59

0

22nd

69

4

13th

60

0

23rd

61

0

14th

77

6

24th

60

0

15th

83

4

25th

69

4

16th

77

6

26th

87

8

17th

61

0

27th

79

7

18th

60

0

28th

64

0

19th

62

0

29th

57

0

20th

81

5

30th

63

1

 

Note that over a five millennium span from 1999 BC to 3000 AD, the max number of eclipse tetrads that any century can have is 8, which occurs this century and last happened in the 9th century AD.

Of course, the visual appearance of a “Blood of the Moon” that’s possibly alluded to in Revelation is a real phenomena that you can see next week from North and South America as the Moon enters into the dark umbra or core of the shadow of the Earth. But this occurs during every total lunar eclipse, and the redness of the Moon is simply due to the scattering of sunlight through the Earth’s atmosphere. Incidentally, this redness can vary considerably due to the amount of dust, ash, and particulate aerosols aloft in the Earth’s atmosphere, resulting in anything from a bright cherry red eclipse during totality to an eclipsed Moon almost disappearing from view altogether… but it’s well understood by science and not at all supernatural.

The changing colors of a lunar eclipse: a mosaic of four eclipses. Photos by author.
The changing colors of a lunar eclipse: a mosaic of four eclipses. Photos by author.

Curiously, the Revelation passage could be read to mean a total solar eclipse as well, though both can never happen on the same day.  Lunar and solar eclipses occur in pairs two weeks apart at Full and New Moon phases when the nodes of the Moon’s ecliptic crossing comes into alignment with the Sun — known as a syzygy, an ultimate triple word score in Scrabble, by the way — and this eclipse season sees a non-central annular eclipse following the April 15th eclipse on April 29th.

And yes, earthquakes, wars, disease, relationship breakups and lost car keys are on tap to occur in 2014 and 2015… just like during any other year. Lunar eclipses marked the fall of Constantinople in 1453 and the World Series victory of the Red Sox in 2004, but they’re far from rare. We humans love to see patterns, and sometimes this habit works against us, making us see them where none exists. This is simply a case of the gambler’s fallacy, counting the hits at the cost of the misses. We could just as easily make a case that the upcoming eclipse tetrad of April 15th, October 8th, April 4th and September 28th marks US Tax Day, Croatian Independence Day, The Feast of Benedict of the Moor & — Michael Scott take note — International World Rabies Day… perhaps the final 2015 eclipse should be known as a “Rabies Moon?”

So, what’s the harm in believing in a little gloom and doom? The harm in believing the world ends tomorrow comes when we fail to plan for still being here the day after. The harm comes when something like the Heavens Gate mass suicide goes down. We are indeed linked to the universe, but not in the mundane and trivial way that astrologers and doomsdayers would have you believe. Science shows us where we came from and where we might be headed.  We’ve already fielded queries from folks asking if it’s safe (!) to stare at the Blood Moon during the eclipse, and the answer is yes… don’t give in to superstition and miss out on this spectacular show of nature because of some internet nonsense.

The upcoming lunar eclipse next week won’t mean the end of the world for anyone, except, perhaps, NASA’s LADEE spacecraft… be sure not to miss it!

 

Lunar Eclipse – Saturday, December 10, 2011

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Are you ready for some good, old-fashioned observing fun? Although you might not want to get up early, it’s going to be worth your time. This Saturday, December 10, 2011, marks the last total lunar eclipse event for the western portion of the Americas until 2014. While a solar eclipse event has a very small footprint where it is visible, a lunar eclipse has a wide and wonderful path that encompasses a huge amount of viewers. “We’re all looking at this together,” says Sky & Telescope senior editor Alan MacRobert.

How much of the dawn lunar eclipse will be visible for you? For your location, this map tells what stage the eclipse will have progressed to by the time the Moon sets below your west-northwestern horizon. Credit: Sky & Telescope
If you live in the eastern portion of the Americas, sorry… You’ll miss out on this one. In the Central time zone, the Moon will be setting while it is partially eclipsed. However, beginning in a line that takes in Arizona and the Dakotas you’ll be treated to the beginning of the lunar eclipse, totality, and it will set as it is beginning to come out of eclipse. If you live in the western portion of the US or Canada? Lucky you! You’ll get to enjoy the Moon as it goes through the initial states of eclipse, see totality and even might catch the phases as it slips out of Earth’s shadow again – just as the Sun begins to rise. For Skywatchers in Hawaii, Australia, and East Asia, you’ll have it better. Seen from there, the whole eclipse happens high in a dark sky from start to finish. For Europe and Africa, the eclipsed Moon will be lower in the east during or after twilight on the evening of the 10th.

When exactly does the event begin? The lunar eclipse will be total from 6:05 to 6:57 a.m. Pacific Standard Time. The partial stage of the eclipse begins more than an hour earlier, at 4:45 a.m. PST. Be sure to watch the southern lunar edge, too. Because the Moon will be skimming by the southern edge of the Earth’s shadow, it will remain slightly brighter and add to the dimensional effect you’ll see. Enjoy the coppery colors from the refracted sunlight! The Moon won’t be black – but it will most certainly be a very photogenic experience.

“That red light on the Moon during a lunar eclipse comes from all the sunrises and sunsets around the Earth at the time,” explains Sky & Telescope editor in chief Robert Naeye. “If you were an astronaut standing on the Moon and looking up, the whole picture would be clear. The Sun would be covered up by a dark Earth that was ringed all around with a thin, brilliant band of sunset- and sunrise-colored light — bright enough to dimly illuminate the lunar landscape around you.”

May clear skies be yours!

Original News Source: Sky and Telescope News Release. Image Credits: Sky and Telescope.