Students in a school in Tanzania view the Sun with Astronomers Without Borders filter glasses. Credit: Astronomers Without Borders.
Astronomers Without Borders – those great folks who do science outreach around the world – is getting ready for the next solar eclipse, which takes place on November 3, 2013. A partial eclipse will be visible across a wide swath of Africa and AWB needs your help so that tens of thousands of eclipse glasses can be sent to schools in Africa in time for the eclipse.
“We’re working with the IAU’s Office of Astronomy for Development who has contacts working with schools and able to distribute the glasses to them,” Mike Simmons, who leads AWB, told Universe Today via email. “The opportunity for this came up late so we’re working very hard to make it happen in the short time we have left.”
Simmons added that this is a rare opportunity to expose students to science in a region where science resources are often non-existent, and AWB will be giving the glasses to schools at no charge.
Animation of 2013 November 3 solar eclipse. The large gray circle shows the area of the partial solar eclipse. The very small dark dot in the middle depicts the path of the total solar eclipse. Credit: NASA/Goddard Space Flight Center.
The AWB website says that schools have been identified and vetted by partner organizations in each country in Africa, and distribution networks have been verified. Every donated pair of eclipse glasses WILL reach a student for use for the eclipse. The International Astronomical Union’s Office of Astronomy for Development, which is based in Cape Town, South Africa, is providing invaluable support and assistance through their many contacts across Africa.
This program depends entirely on donations.
“There’s no question we can get all the donations that are needed as long as we get the word out in time,” Simmons said.
Please consider donating, as AWB does amazing work.
“We do probably a half-million dollars in programs each year based on the hard work of passionate amateur astronomers and educators around the world,” Simmons said, “all on way less than $25,000 a year.”
This is a great astronomy outreach organization that really could use financial help of any kind, so feel free to donate to their general cause, as well.
You can also purchase eclipse glasses for your own use from AWB here.
An occultation of the star Mu Geminorum (to the upper right off the dark limb of the Moon) Photo by author.
The first in a cycle of challenging occultations of the bright star Spica for northern hemisphere observers begins this coming Monday on August 12th.
Watching a bright star or planet wink out on the dark limb of the Moon can be an amazing event to witness. It’s an abrupt “now you see it, now you don’t” event in a universe which often seems to move at an otherwise glacial pace. And if the event grazes the limb of the Moon, an observer may see a series of winks as the starlight streams through the lunar valleys.
Close companion stars have been discovered during occultations, and astronomers even used a series of occultations of radio source 3C 273 in 1962 to pin down the position of the first quasar.
An occultation occurs when one object passes in front of another as seen from the observer’s vantage point. The term has its hoary roots back in a time when astronomy was intertwined with its pseudoscience ancestor of astrology. Even today, I still get funny looks from non-astronomy friends when I use the term occultation, as if it just confirms their suspicions of the arcane arts that astronomers really practice in secret.
But back to reality-based science. At an apparent magnitude of +1.1, Spica is the 3rd brightest star that the Moon can occult along its five degree path above and below the plane of the ecliptic. It’s also one of only four stars brighter than +1.4 magnitude on the Moon’s path. The others are Antares (magnitude +1.0), Regulus (magnitude +1.4), and Aldebaran (magnitude +0.8). All of these are bright enough to be visible on the lunar limb through binoculars or a telescope in the daytime if conditions are favorable.
It’s interesting to note that this situation also changes over time due to the precession of the equinoxes. For example, the bright star Pollux was last occulted by the Moon in 117 BC, but cannot be covered by the Moon in our current epoch.
Spica is currently in the midst of a cycle of 21 occultations by our Moon. This cycle started in July 25th, 2012 and will end in January 2014.
Spica is a B1 III-IV type star 10 times the mass of the Sun. At 260 light years distant, Spica is one of the closest candidates to the Earth along with Betelgeuse to go supernova. Now, THAT would make for an interesting occultation! Both are safely out of the ~100 light year distant “kill zone”.
What follows are the circumstances for the next four occultations of Spica by the Moon. The times are given for closest geocentric conjunction of the two objects. Actual times of disappearance and reappearance will vary depending on the observer’s location. Links are provided for each event which include more info.
Looking westward 30 minutes after sunset for North American viewers on the night of August 12th. (Created by the Author using Starry Night).
First up is the August 12th occultation of Spica, which favors Central Asia and the Asian Far East. This will occur late in the afternoon sky around 09:00 UT and prior to sunset. The waxing crescent Moon will be six days past New phase. North American observers will see the Moon paired five degrees from Spica with Saturn to the upper left on the evening of August 12th.
The footprint for the September 8th occultation of Spica by the Moon. Note that the broken line indicates where the occultation will take place in the daytime sky. ( Credit: Occult 4.1.0.2)
Next is the September 8th daytime occultation of Spica for Europe, the Middle East and northern Africa around ~15UT. This will be a challenge, as the Moon will be a waxing crescent at only 3 days past New. Observers in the Middle East will have the best shot at this event, as the occultation occurs at dusk and before moonset. Note that the Moon also occults Venus six hours later for Argentina and Chile.
Looking to the east the morning of November 2nd for North American observers. (Created by the author using Stellarium).
After taking a break in October (the occultation of October 5 occurs only 23 hours after New and is unobservable), the Moon again occults Spica on November 2nd for observers across Europe & Central Asia. This will be a difficult one, as the Moon will be only 20 hours from New and a hybrid solar eclipse that will cross the Atlantic and central Africa. It may be possible to lock on to the Moon and track it up into the daylight, just be sure to physically block the rising Sun behind a building or hill!
The occultation footprint of Spica by the Moon for November 29th, 2013. (Reproduced from the Astronomical Almanac online and produced by the U.S. Naval Observatory and H.M. Nautical Almanac Office).
Finally, the Moon will occult Spica for North American observers on November 29th centered on 17:03 UT. This will place the event low in the nighttime sky for Alaskan observers. It’ll be a bit more of a challenge for Canadian and U.S. observers in the lower 48, as the Moon & Spica will be sandwiched between the Sun and the western horizon in the mid-day sky. As an added treat, comet C/2012 S1 ISON will reach perihelion on November 28th, just 20 hours prior and will be reaching peak brilliance very near the Sun.
And as an added bonus, the Moon will be occulting the +2.8 star Alpha Librae (Zubenelgenubi) on August 13th for central South America.
All of these events are challenges, to be sure. Viewers worldwide will still catch a close night time pairing of the Moon and Spica on each pass. We’ve watched the daytime Moon occult Aldebaran with binoculars while stationed in Alaska back in the late 1990’s, and can attest that such a feat of visual athletics is indeed possible.
And speaking of which, the next bright star due for a series of occultations by the Moon is Aldebaran starting in 2015. After 2014, Spica won’t be occulted by the Moon again until 2024.
But wait, there’s more- the total eclipse of the Moon occurring on April 15th 2014 occurs just 1.5 degrees from Spica, favoring North America. This is the next good lunar eclipse for North American observers, and one of the best “Moon-star-eclipse” conjunctions for this century. Hey, at least it’ll give U.S. observers something besides Tax Day to look forward to in mid-April. More to come in 2014!
A hypothetical Vulcanoid asteroid in orbit about the Sun. ( Artist's impression in the Public Domain).
One of the most fascinating stories in modern astronomy involves the pursuit of a world that never was.
Tomorrow marks the 135th anniversary of the total solar eclipse of July 29th, 1878. With a maximum totality of 3 minutes 11 seconds, this eclipse traced a path across western Canada and the United States from the territory of Montana to Louisiana.
A curious band of astronomers also lay in wait along the path of totality, searching for an elusive world known as Vulcan.
Long before Star Trek or Mr. Spock, Vulcan was a hypothetical world thought to inhabit the region between the planet Mercury and the Sun.
The tale of Vulcan is the story of the birth of modern predictive astronomy. Vulcan was a reality to 18th century astronomers- it can be seen and the astronomy textbooks and contemporary art and culture of the day. Urbain J.J. Le Verrier proposed the existence of the planet in 1859 to explain the anomalous precession of the perihelion of the planet Mercury. Le Verrier was a voice to be taken seriously — he had performed a similar feat of calculation to lead observers to the discovery of the planet Neptune from the Berlin Observatory on the night of September 23, 1846. Almost overnight, Le Verrier had single-handedly boosted astronomy into the realm of a science with real predictive power.
An 1863 photograph of Lescarbault’s country house observatory. (Wikimedia Commons image in the public domain).
The idea of Vulcan gained traction when a French doctor and amateur astronomer Edmond Lescarbault claimed to have seen the tiny world transit the Sun while viewing it through his 95 millimetre refractor on the sunny afternoon of March 26th, 1859. Keep in mind, this was an era when solar observations were carried out via the hazardous method of viewing the Sun through a smoked or oil-filled filter, or the via safer technique of projecting the disk and sketching it onto a piece of paper.
A early right-angle solar viewer from Robert Ariail collection at the South Carolina State Museum in Columbia, South Carolina. Note the vent holes in the back to dissipate heat, and word SUN stenciled on the side! (Photo by author).
A visiting Le Verrier was sufficiently impressed by Lescarbault’s observation, and went as far as to calculate and publish orbital tables for Vulcan. Soon, astronomers everywhere were “seeing dots” pass in front of the Sun. Astronomer F. A. R. Russell spotted an object transiting the Sun from London on January, 29th, 1860. Sightings continued over the decades, including a claim by an observer based near Peckeloh Germany to have witnessed a transit of Vulcan on April 4th, 1876.
Incidentally, we are not immune to this effect of “contagious observations” even today — for example, when Comet Holmes brightened to naked eye visibility in October 2007, spurious reports of other comets brightening flooded message boards, and a similar psychological phenomena occurred after amateur astronomer Anthony Wesley recorded an impact on Jupiter in 2010. Though the event that triggered the initial observation was real, the claims of impacts on other bodies in the solar system that soon followed turned out to be bogus.
Possible “target zone” for the existence of Vulcan, and later Vulcanoid asteroids. (Graphic in the public domain).
Still, reports of the planet Vulcan were substantial enough for astronomers to mount an expedition to the territory of Wyoming in an attempt to catch dim Vulcan near the Sun during the brief moments of totality. Participants include Simon Newcomb of the Naval Observatory, James Craig Watson and Lewis Swift. Inventor Thomas Edison was also on hand, stationed at Rawlins, Wyoming hoping to test his new-fangled invention known as a tasimeter to measure the heat of the solar corona.
Conditions were austere, to say the least. Although the teams endured dust storms that nearly threatened to cut their expeditions short, the morning of the 29th dawned, as one newspaper reported, “as slick and clean as a Cheyenne free-lunch table.” Totality began just after 4 PM local, as observers near the tiny town of Separation, Wyoming swung their instruments into action.
Such a quest is difficult under the best of circumstances. Observers had to sweep the area within 3 degrees of the Sun (six times the diameter of a Full Moon) quickly during the fleeting moments of totality with their narrow field refractors, looking for a +4th magnitude star or fainter among the established star fields.
Map of the path of the total solar eclipse of July 29th, 1878. (Credit: Fred Espenak/NASA/GSFC).
In the end, the expedition was both a success and a failure. Watson & Swift both claimed to have identified a +5th magnitude object similar in brightness to the nearby star Theta Cancri. Astronomer Christian Heinrich Friedrich Peters later cast doubt on the sighting and the whole Vulcan affair, claiming that “I refuse to go on a wild goose chase after Le Verrier’s mythical birds!”
And speaking of birds, Edison ran into another eclipse phenomenon while testing his device, when chickens, fooled by the approaching false dusk came home to roost at the onset of totality!
Vulcan search map for the Smithsonian Observatory’s 1900 eclipse expedition. (From the collection of Michael Zeiler@EclipseMaps, used with permission).
But such is the life of an eclipse-chaser. Albert Einstein’s general theory of relativity explained the precession of Mercury’s orbit in 1916 and did away with a need for Vulcan entirely.
But is the idea of intra-Mercurial worldlets down for the count?
The search strategy for NASA’s high-altitude mission to hunt for Vulcanoids in 2002. (Credit: NASA/Dryden).
Amazingly, the quest for objects inside Mercury’s orbit goes on today, and the jury is still out. Dubbed Vulcanoids, modern day hunters still probe the inner solar system for tiny asteroids that may inhabit the region close to the Sun. In 2002, NASA conducted a series of high altitude flights out of the Dryden Flight Research Center at Edwards Air Force Base, California, sweeping the sky near the Sun for Vulcanoids at dawn and dusk. Now, there’s a job to be envious of — an F-18 flying astronomer!
One of NASA’s fleet of high-performance F-18 aircraft. (Credit: NASA).
NASA’s MESSENGER spacecraft was also on the lookout for Vulcanoids on its six year trek through the inner solar system prior to orbital insertion on March 18th, 2011.
Thus far, these hunts have turned up naught. But one of the most fascinating quests is still ongoing and being carried out by veteran eclipse-chaser Landon Curt Noll.
Mr. Noll last conducted a sweep for Vulcanoids during total phases of the long duration total solar eclipse of July 22nd, 2009 across the Far East. He uses a deep sky imaging system, taking pictures in the near-IR to accomplish this search. Using this near-IR imaging technique during a total solar eclipse requires a stable platform, and thus performing this feat at sea or via an airborne platform is out. Such a rig has been successful in catching the extremely thin crescent Moon at the moment it reaches New phase.
Mr. Noll explains the aspects of an eclipse during a 2006 expedition to Libya. (Coutesy of Landon Curt Noll, used with permission).
To date, no convincing Vulcanoid candidates have been found. Mr. Noll also notes that the European Space Agency/NASA’s joint Solar Heliospheric Observatory (SOHO) spacecraft has, for all intents and purposes, eliminated the possibility of Vulcanoids brighter than +8th magnitude near the Sun. Modern searches during eclipses conducted in this fashion scan the sky between wavelengths of 780 to 1100 nanometres down to magnitude +13.5. Mr. Noll told Universe Today that “Our improved orbital models show that objects as small as 50m in diameter could reside in a zone 0.08 A.U. to 0.18 AU (1.2 to 2.7 million kilometers) from the Sun.” He also stated that, “there is plenty of ‘room’ for (Vulcanoids) in the 50 metre to 20 kilometre range.”
The modern day Vulcanoid search strategy. (Diagram courtesy of Landon Curt Noll, used with permission).
Mr. Noll plans to resume his hunt during the August 21st, 2017 total solar eclipse spanning the continental United States. Totality for this eclipse will have a maximum duration of 2 minutes and 40 seconds. Circumstances during the next solar eclipse (a hybrid annular-total crossing central Africa on November 3rd, 2013) will be much more difficult, with a max totality located out to sea of only 1 minute and 40 seconds.
Mr. Noll talks with a local reporter during the 2006 total solar eclipse expedition to Libya. (Photograph courtesy of Landon Curt Noll, used with permission).
Still, we think it’s amazing that the quest for Vulcan (or at least Vulcanoids) is alive and well and being spearheaded by adventurous and innovative amateur astronomers. In the words of Vulcan’s native fictional son, may it “Live Long & Prosper!”
This is an image of a unique eclipse as viewed by NASA's Solar Dynamics Observatory, with a model of the moon from NASA's Lunar Reconnaissance Orbiter replacing the lunar shadow. Credit: NASA/SDO/LRO/GSFC
You’ve probably never before seen an image like the one above. That’s because it is the first time something like this has ever been created, and it is only possible thanks to two fairly recent NASA missions, the Solar Dynamics Observatory and the Lunar Reconnaissance Orbiter. We’ve shared previously how two or three times a year, SDO goes through “eclipse season” where it observes the Moon traveling across the Sun, blocking its view.
Now, Scott Wiessinger and Ernie Wright from Goddard Space Flight Center’s Scientific Visualization Studio used SDO and LRO data to create a model of the Moon that exactly matches SDO’s perspective of a lunar transit from October 7, 2010. They had to precisely match up data from the correct time and viewpoint for the two separate spacecraft, and the end result is this breathtaking image of the Sun and the Moon.
“The results look pretty neat,” Wiessinger said via email, “and it’s a great example of everything working: SDO image header data, which contains the spacecraft’s position; our information about lunar libration, elevation maps of the lunar surface, etc. It all lines up very nicely.”
‘Nicely’ is an understatement. How about “freaking awesome!”
And of course, they didn’t just stop there.
his is an up close shot of two NASA images: An image rendered from a model of the moon from the Lunar Reconnaissance Orbiter overlaid onto an image of the sun from the Solar Dynamics Observatory, during a lunar transit as seen by SDO on Oct. 7, 2010. The various features of the moon’s horizon are labeled. Credit: NASA/SDO/LRO/GSFC
Since the data from both spacecraft are at such high resolution, if you zoom in to the LRO image, features of the Moon’s topography are visible, such as mountains and craters. This annotated image shows what all is visible on the Moon. And then there’s the wonderful and completely unique view in the background of SDO’s data of the Sun.
So while the imagery is awesome, this exercise also means that both missions are able to accurately provide images of what’s happening at any given moment in time.
The image on the left is a view of the sun captured by NASA’s Solar Dynamics Observatory on Oct. 7, 2010, while partially obscured by the moon. Looking closely at the crisp horizon of the moon against the sun shows the outline of lunar mountains. A model of the moon from NASA’s Lunar Reconnaissance Orbiter has been inserted into a picture on the right, showing how perfectly the moon’s true topography fits into the shadow observed by SDO. Credit: NASA/SDO/LRO/GSFC
As the first eclipse season of 2013 comes to an end this weekend, an extremely subtle lunar eclipse occurs on the night of Friday, May 24th going into the morning of Saturday, May 25th. And we do mean subtle, as in invisible to the naked eye… this eclipse only lasts 34 minutes in duration and less than 2% of the disk of the Moon enters the bright outer penumbra of the Earth’s shadow!
So, why talk about such a non-event at all?
Great things come from such humble beginnings. And while this weekend’s eclipse is one mostly for the almanacs and astronomical tables rather than a true observational event, it also marks the start of a new lunar saros cycle.
This weekend’s eclipse is one of five for 2013, a year which contains two solars and three lunars. This eclipse marks the end of the first “eclipse season” of the year, a time when the intersection of the Moon’s orbit (known as nodes) and the ecliptic nearly coincide with the position of the Sun (for a solar eclipse at New Moon) and the Earth’s shadow (for a lunar eclipse at Full Moon).
The current season began with a very slight partial eclipse on April 25th, followed by an annular eclipse on May 10th. It will last only 33 minutes and 45 seconds in duration starting at 03:53:11 UTC on May 25th. The Moon will be high over the Americas at the time, but again, shading on the southern limb of the Moon will be too slight to be seen.
Curiously, SLOOH will be providing live coverage of the eclipse, although again, it will be too slight to see.
The Full Moon just nicks the Earth’s penumbra in the early morning hours of May 25th. (Created by the author in Starry Night).
What is a saros? A saros is a period of 18 years 11 days and 8 hours after which an eclipse cycle lines up, producing a similar eclipse to the one that preceded it 18 years before. Note that due to its 8 hour offset, the Earth will have rotated 120° and the visibility region will have shifted westward.
In said period, three lunar cycles very nearly line up;
The Anomalistic month (the period the Moon takes to go from one perigee to another) = 27.555 days.
The Draconic month (the period the Moon takes to return to the same node) = 27.212 days.
The Synodic month (the most familiar one, the period between similar phases) = 29.531 days.
There’s that mis-alignment of a third of a day again (8 hours) for every 18 years and 11 days. This also causes the node of each eclipse in the cycle to drift eastward by 0.5° along the ecliptic. Thus, each eclipse isn’t exactly the same. A lunar saros series starts with a very brief penumbral like this weekend’s, becomes deeper and deeper every 18+ year period until partial and total eclipses begin centuries down the road. Thereafter, the cycle reverses, until a final faint penumbral marks the end of the lunar saros.
The progression of selected eclipses of the same saros cycle. (Credit: Matthew Zimmerman. Wikimedia Commons graphic in the Public Domain).
After this weekend’s eclipse, the next start of a lunar saros won’t occur until November 8th 2060 with the start of saros 156. The last new saros series (number 149) began on June 13th, 1984.
There are numbered saros series for both lunar and solar eclipses. There are currently 41 saroses (the plural of saros) active with the inclusion of this weekend’s start of lunar saros 150.
Saros 150, of which this eclipse is the 1st of 71, will last for just over 1,262 years. It will begin to produce partial eclipses on August 20th, 2157 and produce its 1st total on its 32nd lunar eclipse on April 29th, 2572.
It amazes me that ancient cultures such as the Chaldeans new of saros cycles and could predict eclipses. Being geographically isolated, lunar eclipse cycles would have been easier to decipher than solar ones, as you only have to be on the Moonward facing hemisphere of the Earth to witness the eclipse. They may well have stumbled upon the saros while attempting to calculate a slightly longer 19 year period known as a Metonic cycle to align ancient luni-solar calendars.
And yes, that 8 hour offset also means that after a triple saros period, lunar and solar eclipses of the same saros series do return to roughly the same longitude every 54 years & 34 days. This is known as an exeligmos, and if you get this on a triple-word score in Scrabble, you can safely retire from the game.
The theoretical visibility circumstances for this week’s penumbral eclipse. (Credit: F. Espenak/NASA/GSFC).
And while this eclipse is more of academic than observational interest, you can always enjoy the light of a brilliant Full Moon. The May Full Moon is referred to as the Flower, Milk, and Corn Planting Moon by the Algonquian Indians of North America, alluding the latent season of Spring.
Also, keep an eye out for several conjunctions and occultations this week by the Moon with bright stars and planets.
The first up is the bright star Spica (Alpha Virginis) which gets occulted by the waxing gibbous Moon around ~11:00 UT on Wednesday, May 22nd for viewers across northern Australia, southern Asia and the South Pacific. Spica is one of four stars brighter than magnitude +1.5 that the Moon can occult, the others being Antares, Aldebaran and Regulus. This is the 6th occultation in a cycle of 13 of Spica by the Moon spanning 2013.
The planet Saturn will lie about 4° north of the waxing gibbous Moon on the following evening of May 23rd.
Also, watch for an occultation of the +2.6th magnitude star Beta Scorpii on the evening of May 24th around the time of the lunar eclipse. This will be a difficult one, as the Moon will be near 100% illumination. Conjunction of the Moon and Beta Scorpii in right ascension occurs at 3:04 UT on May 25th, about 2.5 hours after Full. The occultation will span the southeastern US, Caribbean, northern South America and western Africa.
Visibility path of the occultation of Beta Scorpii by the Moon. (Credit: Occult 4.1.0.2).
2013 isn’t a grand year for eclipses. We’ve got two more in the late season of the year, another slightly deeper penumbral on October 18th and a hybrid solar eclipse on November 3rd. And when, may you ask, will we FINALLY have another total lunar eclipse? Stick around ‘til U.S. Tax Day next year (April 15th 2014) for a total lunar eclipse spanning the Americas!
Images and videos are still coming in from last week’s spectacular annular eclipse of the Sun, seen across Australia and the southern Pacific region on May 10, 2013. This gorgeous timelapse by Colin Legg captures the eclipse from 3 locations in the Pilbara, Western Australia where the Sun was rising at the time of the event. “If you ever get to see an annular eclipse, I recommend going to the path limits (sunset or sunrise),” Legg said on Vimeo. “All sorts of weird things happen to the Sun, right on the horizon.”
A three image sequence of the rising annular eclipse. Credit: Geoff Sims. (@beyond_beneath)
Just when we’d thought that we’ve seen every possible type of eclipse image, we’re happily surprised by the Universe.
If you’re like me, you watch the original Star Wars film and wonder what kind of eclipses could be seen from the surface of Tatooine. Maybe you even wonder what things would look like if an extra sun and moon were to be thrown into the mix. How often, if ever, would such a bizarre alignment sync up?
Astrophotographer Geoff Sims provided us with just such a bizarre view this past weekend.
Geoff was one of a handful of intrepid photographers that braved the wilds of the Australian Outback to deliver us some stunning views of last week’s rising annular eclipse. We wrote of how to observe this celestial wonder late last month on Universe Today, and documented the efforts of photographers, both Earthbound and otherwise, the day of the eclipse this past Friday.
For this amazing image, Geoff positioned himself along the track of annularity in the Great Sandy Desert in Western Australia. Even the name of the site, the Plutonic Gold Mine outside of Newman, Australia couldn’t be beat!
The series is a composite of three exposures which were taken about three minutes apart. Mr. Simms relates how he accomplished this unforgettable image on his Facebook page:
“The lower image shows a flattened and distorted Sun perched right on the horizon, just seconds before the annular eclipse began. The middle image shows the annular phase, while the upper image shows the Sun some minutes after annularity.”
Mr. Sims used a Canon Mark III DSLR camera with a 500mm lens shooting at 1/1,000th of a second exposures at a focal ratio of f/8 and an ISO setting of 100.
Amazingly, other photographers positioned very near the eclipse graze line caught sight of what are known as Bailey’s Beads as well. More commonly seen during a total solar eclipse, these are caused by sunlight streaming through ridges and valleys on the limb of the Moon. This can also cause the brilliant diamond ring effect seen during a total solar eclipse. In the case of an annular eclipse, this manifests as a ragged broken edge where the disk of the Sun meets the Moon:
Bailey’s Beads captured very briefly during last week’s annular eclipse. (Credit: Geoff Sims).
An annular eclipse occurs when the Moon eclipses the Sun near apogee, or its most distant point in its orbit and is hence visually too small to cover the Sun as seen from the Earth. A similar eclipse occurred over the Pacific and the western U.S. last year on May 20th, leading to a series of “horned sunset” photos taken across Texas and New Mexico.
But what is the most astonishing aspect of the eclipse sequence is the extreme distortion occurring across the very bottom image sitting on the horizon. When you’re looking low to the horizon, you’re viewing objects through a thicker cross-section of the atmosphere. This is what is termed as a higher air mass, and most astro-imagers avoid it entirely, preferring to catch objects with as little distortion as possible as they transit across the local meridian. This distortion can be extreme enough to result in atmospheric refraction of rising and setting objects like the Sun, Moon or planets, causing them to appear moments before or after they actually rose or set over the local horizon. In the case of the bottom image, the lower limb of the solar annulus (the technical name for what folks call the “ring of fire” seen during an annular eclipse) is actually distorted enough to appear along the rim of the local horizon!
To our knowledge, such an extremely distorted eclipse has never been documented before. One also wonders if a “green flash” could be captured by a properly positioned observer on a mountaintop or out to sea during a sunset or sunrise annular or total solar eclipse.
Newsflash: the green flash was indeed captured during last week’s annular eclipse… check out this amazing animation:
2013 will offer one more chance to try to repeat this feat. On November 3rd, a hybrid solar eclipse will race across the Atlantic Ocean and central Africa. This is an eclipse that is literally an annular across a portion of its track and a total across another. The eclipse will begin at sunrise just south of Bermuda and end at sunset in eastern Africa. The maximum period of totality is 1 minute and 40 seconds off of the coast of Liberia, and the southern regions of Ethiopia offer the best shot at a sunset eclipse. Tantalizingly, the Florida Space Coast will get a rising partial eclipse only a few percent in magnitude.
Kudos to Mr. Sims for providing us with an unforgettable view of this rare cosmic spectacle. Australia won’t see another total solar eclipse until July 22nd, 2028, and another purely annular eclipse won’t occur until April 29th, 2014 across a very small section of the Antarctic.
And next week, we’ll have a very shallow penumbral eclipse on May 25th, and event is so subtle that few if any will notice it. Still, it is from such humble beginnings that great things are made, as we witness the birth of a new lunar saros… stay tuned!
@Beyond_Beneath Geoff Sims Plutonic Gold Mine, Australia
A spectacular annular eclipse of the Sun was witnessed across Australia and the southern Pacific region early today. Morning dawned mostly clear across the Australian continent, and those who journeyed out to meet the antumbra of the Moon as the Sun rose across the Great Sandy Desert and the Cape York Peninsula were not disappointed. The rest of us watched worldwide on as Slooh and a scattering of other ad-hoc broadcasts delivered the celestial event to us via the web.
This was a challenging one. Although partial phases of the eclipse was visible across the entirety of Australia, Hawaii, and as far north as the Philippines and as far south as New Zealand, the track of annularity passed over some very remote locales. Stable Internet connections were scarce, and many photos and videos are still trickling in as die-hard eclipse chasers return “from the Bush.”
One lucky witness to the eclipse was Druce Horton (Xylopia on flickr) who caught the eclipse from Kuranda, Australia just north of Cairns. “It was completely clouded over here in Kuranda and I didn’t even bother going to a place where I could get a clear view.” Druce told Universe Today. “I then noticed the sky lightening a little and I rushed out with the camera and desperately tried to set an appropriate exposure and frame it while avoiding getting an eyeful of sunlight and/or a tree branch in the way.”
A rising crescent eclipse as seen by Druce Horton near Kurunda, Australia. (Credit and Copyright: Druce Horton. Used with Permission).
As pointed out the us by Michael Zeiler (@EclipseMaps) earlier this week, the town of Newman and surrounding regions in Western Australia were a great place to witness the rising annular eclipse. Geoffrey Sims ventured out and did just that:
Note how the atmospheric haze is distorting the solar annulus into a flattened ring… pure magic! Mr. Sims got some truly stunning pictures of the eclipse, and was one of the first to manage to get them out onto the Internet, though he stated on Twitter that it “will likely take weeks to sort through the images!”
All get reasons to keep a close eye on Mr. Sims’ Facebook page…
Mr. Joerg Schoppmeyer also ventured about 70 kilometres south of Newman to catch the rising “Ring of Fire”:
Annularity just moments after internal contact of the antumbra. Credit: Joerg Schoppmeyer).
We also mentioned earlier this week how you can use the “strainer effect” to create a flock of crescent Suns during a partial solar eclipse.
Amanda Bauer (@astropixie) of Sydney, Australia did just this to create her name in “eclipse pacmans”:
And speaking of which, eclipse crescents can turn up in the most bizarre of places, such as a lens flare caught by a webcam based at the Canberra Deep Space Network:
Trevor Sellman (@tsellman) based in northern Melbourne preferred to catch sight of the partial phase of the eclipse “the old fashioned way,” via a simple pinhole projection onto a white sheet of paper:
In addition to Slooh, the Mead West Vaco Observatory in conjunction with the Columbus State University’s Coca-Cola Space Science Center provided an excellent webcast of the full phases of the eclipse, and in multiple wavelengths to boot:
The solar annulus as seen near mid-eclipse in hydrogen alpha. (Credit: the CCSSC).
And they also provided a view in Calcium-K:
A screen capture of the final stage of the eclipse as seen in Cal-K. (Credit: the CCSSC).
But Earth bound-observers weren’t the only ones on hand to witness this eclipse. Roskosmos also released a video animation of the antumba of the Moon crossing the Earth as seen from the Elektro-L satellite:
“These images interest Russian space enthusiasts because we asked Roskosmos to optimize (the) work of satellite for best pictures of eclipse,” Vitaliy Egorov told Universe Today.
There’s no word as of yet if the NASA/JAXA spacecraft Hinode or if ESA’s Proba-2 caught the eclipse, although they were positioned to take advantage of the opportunity.
There were also some active sunspot regions on the Earthward face of the Sun, as captured by Monty Leventhal in this outstanding white-light filtered image:
Another fine video animation of the eclipse turned up courtesy of Steve Swayne of Maleny in Queensland, Australia;
And finally, Vanessa Hill caught the partial stage of the eclipse while observing from the CSIRO Astrophysics & Space Sciences viewing event:
Partial stages of the eclipse were also captured by Carey Johnson (@TheTelescopeGuy) from Hawaii and can be viewed on his flickr page.
If this eclipse left you jonesin’ for more, there’s a hybrid solar eclipse across the Atlantic and central Africa on November 3rd 2013. Maximum totality for this eclipse is 1 minute and 40 seconds. Unfortunately, after two solar eclipses in 6 months, another total solar eclipse doesn’t grace the Australian continent until July 22nd, 2028!
But such are the ways of the cosmos and celestial mechanics… hey, be glad we occupy a position in space and time where solar eclipses can occur.
Thanks to all who sent in photos… if you’ve got a picture of today’s eclipse, an anecdote, or just a tale of triumph and/or eclipse chasing tribulations drop us a line & share those pics up to the Universe Today flickr group. See you next syzygy, and may all your eclipse paths be clear!
A perfect ring of fire captured by Kevin Baird on May 20th, 2012 from Bluit New Mexico. (Credit: Kevin Baird/Universe Today flickr Group).
The first solar eclipse of 2013 is upon us this week, with the May 10thannular eclipse crossing northern Australia and the Pacific.
2013 is an off year for eclipses. There are five eclipses this year, three lunars and two solars. Last month’s very shallow partial lunar eclipse set us up for the annular that occurs this week. In fact, the theoretical mid-point for the first of two eclipse seasons for 2013 occurs on May 7th at 7:00 UT/ 3:00 EDT when the longitude of the Sun equals the descending node where the Moon’s path crosses the ecliptic. This further sets us up for the third and weakest eclipse of the year, a grazing penumbral on May 25th.
Animation of the path of this week’s annular solar eclipse. (Credit: NASA/GSFC/A.T. Sinclair).
An annular eclipse occurs when the Moon eclipses the Sun while near apogee and is hence visually too small to entirely cover the Sun.
The Moon reaches apogee on May 13th at 13:32 UT/9:32AM EDT at 405,826 kilometres from Earth, just 3 days and 13 hours past New.
Annulars are currently more common than total solar eclipses, occurring 33.2% of the time in our current 5,000 year epoch versus 26.7% for total solar eclipses. The remainders are hybrid and partial eclipses. Annulars will become even more common as our Moon recedes from us at a current rate of about 3.8 centimetres a year. In about 1.4 billion years, the final brief total solar eclipse as seen from the Earth will occur. Likewise, somewhere back about 900 million years ago, the very first annular eclipse as seen from the Earth occurred.
Solar viewing with a properly fitted glass white light filter over the aperture of a Schmidt-Cassegrain telescope. (Photo by Author).
Safety is paramount while viewing an annular solar eclipse. As mentioned above, an annular eclipse throughout all phases is much brighter than you’d expect. Thus precautions to protect your eyes MUST be taken throughout ALL phases of the eclipse. Permanent eye damage can result from staring at the Sun without proper protection, and this can be near instantaneous when done through an unfiltered telescope!
We witnessed the 1994 annular eclipse from the shores of Lake Erie, and can tell you that 5% of the Sun is still extremely bright. You wouldn’t even know an annular eclipse was underway at midday unless you were looking for it. Use only filters approved for eclipse viewing that fit snugly over the FRONT of your optics. Throw those old eyepiece screw-on filters away, as they can heat up and crack!
Check filters before use and never leave a telescope aimed at the Sun unattended. Projecting the Sun is another option via a telescope or “Sun Gun,” but again, never leave such a rig unattended, and keep finderscopes covered at all times. Also, telescopes with folded optical paths such as Schmidt-Cassegrains can heat up to dangerous levels and should not be used for projecting the Sun.
The path of the May 9th/10th annular eclipse across Australia & the Pacific. (Map courtesy of Michael Zeiler at Eclipse Maps, click to enlarge).
This eclipse has a magnitude rating of 0.9544, meaning that 95.44% of the diameter of the Sun will be eclipsed at its maximum. Keep in mind, this leaves about 8.9% percent of the Sun, or about 1/11th of its visual area exposed. This translates to only a 2.5 magnitude drop in brightness. Thus, the brightness of the Sun will drop from magnitude -27 to -24.5, still well over 25,000 times brighter than the Full Moon!
Note that this one crosses the International dateline as well.
The action for this eclipse begins as the partial phases touch down over Western Australia at sunrise at 21:25 UT on May 9th (The morning of May 10th in Australia). The annulus makes its appearance at 22:30 UT over western Australia, with its 172 kilometre wide track racing to the northeast over Tennant Creek in the Northern Territories and crossing the Cape York peninsula as it crisscrosses the path of last November’s total solar eclipse just north of Cairns.
A closeup of the path of the annular eclipse across Australia, click to enlarge. (Courtesy of Miichael Zeiler at Eclipse Maps).
Note that the eclipse will be 80% partial near Alice Springs and Uluru (Ayers Rock), presenting an excellent photo op. Michael Zeiler at Eclipse Maps also points out that the area near the town of Newman in Western Australia will see an amazing sunrise annular eclipse. The path of the annular eclipse will then traverse the Coral Sea crossing over islands in eastern Papua New Guiana, the Solomon Islands and Kiribati before reaching greatest annularity with a duration of 6 minutes and 3 seconds at latitude 2° 13’ north and longitude 175° 28’ east. The path of annularity crosses over Bairiki Atoll and makes last landfall over Fanning Island north of Kiribati. Note that most of Australia, New Zealand, Indonesia and the Philippines will see partial phases of the eclipse. The islands of Hawaii across the dateline will also see a 40-50% partial eclipse on May 9th before the event ends in the eastern Pacific at 03:25:23 UT.
Weather prospects for the eclipse look to be best along the track through Australia with less than 20% chance of cloud cover then getting progressively worse as the eclipse path tracks northeastward out to sea. The Solomon Islands region can expect cloud cover in the 60% range, while in Hawaii prospects are about 70%. Eclipser maintains a site dedicated to weather prospects for upcoming eclipses.
Solar activity is currently moderate, with several sunspot groups currently turned Earthward making for a photogenic Sun on eclipse day;
Sunspot activity as of May 5th. (Photo by Author).
This eclipse belongs to saros series 138 and is number 31 of 70. This saros started with a 2% partial solar eclipse on June 6th, 1472 and will end with a 12% partial on July 11th,2716 AD having produced 3 total, 1 hybrid, 16 partial and 50 annular eclipses.
Fans of this saros may remember the last annular in this series which crossed South America on April 29th, 1995.
A sequence of eclipse pictures taken from Huntington Beach, California on May 20th, 2012. (Credit: jimnista/Universe Today flickr gallery).
Catching a rising annular eclipse can also make for a stunning photograph. To catch the eclipse and the foreground horizon in silhouette, a DSLR with a 400mm lens running at 1/500th of a second shutter speed or faster is a good combination. Remember, you’ll have to aim this via projection. DO NOT look through the camera at the Sun! Exposures slower than 1/200th of a second are also out of the question, as you can damage the camera sensor at slow exposures.
Another cool effect to watch for is the appearance of tiny little “crescent Suns” littering the ground as sunlight streams through gaps in the tree leaves. This occurs because the gaps act like tiny little pinhole cameras. A spaghetti strainer is also a highly scientific apparatus that can be used to mimic this effect!
Several solar observing satellites, including Hinode and the European Space Agency’s Proba-2 are poised to catch multiple partial solar eclipses on May 9th and 10th. We ran simulations of these this weekend:
Finally, if you’re like 99.99% of humanity, you’ll be watching this eclipse online. Slooh will be broadcasting this eclipse live.
Also, the eclipse will be broadcast live via the Coca-Cola Space Science Center starting at 5PM ET.
Amateur astronomer Geoff Sims @beyond_beneath will be tweeting near real time images of the eclipse from the path of annularity. Colin Legg (@colinleggphoto) will also be observing the event. Also check out:
-Australian observer Gerard Lazarus’s live feed of the eclipse.
Got an ad hoc eclipse broadcast planned? Let us know and we’ll include it!
The next and final solar eclipse for 2013 is a hybrid (annular along one section of the path and total along another) on November 3rd across the mid-Atlantic and central Africa. Another annular eclipse doesn’t occur until April 29th 2014, and the next total solar eclipse occurs on March 20th, 2015.
If you’re in the region be sure to catch this rare celestial event in person, or watch the action worldwide online!
A shattered Luna as depicted in the summer blockbuster Oblivion. (Credit: Universal Pictures).
AVAST gentle reader: mild SPOILER(S) and graphic depictions of shattered satellites ahead!
We recently had a chance to catch Oblivion, the first summer blockbuster of the season. The flick delivers on the fast-paced Sci-Fi action as Tom Cruise saves the planet from an invasion of Tom Cruise clones.
But the movie does pose an interesting astronomical question: what if the Earth had no large moon? In the movie, aliens destroy the Earth’s moon, presumably to throw our planet into chaos. You’d think we’d already be outclassed by the very definition of a species that could accomplish such a feat, but there you go.
Would the elimination of the Moon throw our planet into immediate chaos as depicted in the film? What if we never had a large moon in the first place? And what has our nearest natural neighbor in space done for us lately, anyway?
Earth is unique among rocky or terrestrial planets in that it has a relatively large moon. The Moon ranks 5th in diameter to other solar system satellites. It is 27% the diameter of our planet, but only just a little over 1/80th in terms of mass.
Clearly, the Moon has played a role in the evolution of life on Earth, although how necessary it was isn’t entirely clear. Periodic flooding via tides would have provided an initial impetus to natural selection, driving life to colonize the land. Many creatures such as sea turtles take advantage of the Full Moon as a signal to nest and breed, although life is certainly resilient enough to find alternative methods.
The 2000 book Rare Earth by Peter Ward and Donald Brownlee cites the presence of a large moon as just one of the key ingredients necessary in the story of the evolution of life on Earth. A Moon-less Earth is also just one of the alternative astronomical scenarios cited by Arthur Upgreen in his 2005 book Many Skies.
Save our satellite: A possible target for an alien attack? (Photo by author).
Contrary to its depiction on film, the loss of the Moon wouldn’t throw the Earth into immediate chaos, though the long term changes could be catastrophic. For example, no study has ever conclusively linked the Moon to the effective prediction of terrestrial volcanism and earthquakes, though many have tried. (Yes, we know about the 2003 Taiwanese study, which found a VERY weak statistical signal).
All of that angular momentum in the Earth-Moon system would still have to go somewhere. Our Moon is slowly “braking” the rotation of the Earth to the tune of about 1 second roughly every 67,000 years. We also know via bouncing laser beams off of retro-reflectors left by Apollo astronauts that the Moon is receding from us by about 3.8 cm a year. The fragments of the Moon would still retain its angular momentum, even partially shattered state as depicted in the film.
The most familiar effect the Moon has on Earth is its influence on oceanic tides. With the loss of our Moon, the Sun would become the dominant factor in producing tides, albeit a much weaker one.
But the biggest role the Moon plays is in the stabilization of the Earth’s spin axis over long scale periods of time.
Milankovitch cycles play a long term role in fluctuations in climate on the Earth. This is the result of changes in the eccentricity, obliquity and precession of the Earth’s axis and orbit. For example, perihelion, or our closest point to the Sun, currently falls in January in the middle of the northern hemisphere winter in the current epoch. The tilt of the Earth’s axis is the biggest driver of the seasons, and this varies from 22.1° to 24.5° and back (this is known as the change in obliquity) over a span of 41,000 years. We’re currently at a value of 23.4° and decreasing.
But without a large moon to dampen the change in obliquity, much wider and unpredictable swings would occur. For example, the rotational axis of Mars has varied over a span of 13 to 40 degrees over the last 10 to 20 million years. This long-term stability is a prime benefit that we enjoy in having a large moon .
Perhaps some astronomers would even welcome an alien invasion fleet intent on destroying the Moon. Its light polluting influence makes most deep sky imagers pack it in and visit the family on the week surrounding the Full Moon.
But I have but two words in defense of saving our natural satellite: No eclipses.
The diamond ring effect as seen during a 2008 total solar eclipse. (Credit: NASA/Exploratorium).
We currently occupy an envious position in time and space where total solar and lunar eclipses can occur. In fact, Earth is currently the only planet in our solar system from which you can see the Moon snugly fit in front of the Sun during a total lunar eclipse. It’s 1/400th the size of the Sun, which is also very close to 400 times as distant as the Moon. This situation is almost certainly a rarity in our galaxy; perhaps if alien invaders did show up, we could win ‘em over not by sending a nuclear-armed Tom Cruise after ‘em, but selling them on eclipse tours… Continue reading “Into Oblivion: What If the Earth Had No Moon?”
