One of nature’s grandest ‘occultations’ of all is coming right up this Friday, as the Moon passes in front of the Sun for viewers in the high Arctic for a total solar eclipse. And although 99.999+% percent of humanity will miss totality, everyone can trace the fascinating path of the Moon as it moves back into the evening sky this weekend.
As of this writing, it looks like the fickle March weather is going to keep us guessing right up to eclipse day. Fear not, as the good folks over at the Virtual Telescope Project promise to bring us views of the eclipse live. Not only does this eclipse fall on the same day as the start of astronomical spring in the northern hemisphere known as the vernal (northward) equinox, but it also marks the start of lunation 1141.
Ever try hunting for the slender crescent Moon in the dawn or dusk sky? The sport of thin Moon-spotting on the days surrounding the New Moon can push visual skills to the very limit. Binoculars are your friend in this endeavor, as you sweep back and forth attempting to see the slim fingernail of a Moon against the low contrast background sky. Thursday morning March 19th provides a great chance for North American observers to spy an extremely thin Moon about 24 hours prior to Friday’s eclipse.
Projected locales for the first sightings of the slim crescent Moon on the evening of March 20th. Credit: Created by author.
Unfortunately, most of North America misses the eclipse, though folks on the extreme east coast of Newfoundland might see a partially eclipsed sunrise if the day dawns clear.
The Moon will first be picked up in the evening sky post-eclipse this weekend. On Friday evening, folks in the southern United States might just be able to spy a 15 hour old Moon with optical assistance if skies are clear.
As the Moon fattens, expect to see it at its most photogenic as Ashen light or Earthshine illuminates its nighttime side. What you’re seeing is sunlight from the Earth being reflected back in a reverse (waning gibbous) phase as seen from the earthward side of the Moon. The prominence of Earthshine can vary depending on the amount of cloud and snow cover currently turned moonward, though of course, if it’s cloudy from your location, you won’t see a thing…
The universe smiles back: A skewed emoticon grouping of Venus, Mars and the Moon plus Earthshine on February 20th. Photo by author.
Watch that Moon over the coming weeks, as it has a date with destiny.
The Moon occults (passes in front of) two planets and one bright star in the coming week. First up is an occultation of Uranus on March 21st at around 11:00 UT/7:00 AM EDT. Sure, this one is for the most part purely academic and unobservable, as it occurs over central Africa in the daytime and is only 15 degrees east of the Sun. Still, if you can pick up the Moon on the evenings of March 20th or March 21st, you might just be able to spy nearby Uranus shining at +6th magnitude nearby before it heads towards solar conjunction on April 6th.
The visibility footprint of the March 21st occultation of Mars by the Moon. Credit: Occult 4.1.
Next, the Moon occults Mars on March 21st at 22:00 UT/6:00 PM EDT for the southern Pacific coast of South America. North America will see an extremely close photogenic pairing of Luna and the Red Planet. This is one of seven occultations of a naked eye planet by the Moon for 2015, and the first of two for Mars for the year, the next falling on December 6th.
The Moon pairs with Venus on the evening of March 22nd. Credit: Stellarium.
Next up, the Moon has a tryst with brilliant Venus, passing 2.8 degrees from the Cytherean world on March 22nd. Can you spy -4th magnitude Venus near the two day old Moon before sunset? This is the stuff that has inspired astronomically-themed flags and skewed emoticon ‘smiley face conjunctions’ of yore, including the close pairing of Mars, Venus and the Moon seen worldwide last month.
The occultation of Aldebaran by the Moon on March 25th. Credit: Occult 4.1.
Next up, the 30% illuminated Moon occults the bright star Aldebaran for Alaskan viewers at dusk on March 25th. This is the third occultation of the star by the Moon in the ongoing cycle, and to date, no one has, to our knowledge, successfully caught an occultation of Aldebaran in 2015… could this streak be broken next week?
The daytime Moon paired with Jupiter on March 30th. Credit: Starry Night Education software.
And speaking of daytime planet-spotting, Jupiter will sit only five degrees south of the waxing gibbous Moon on the evening of March 30th. Can you spy the giant planet near the daytime Moon in the afternoon sky using binocs? And finally, watch that Moon, as it heads for the third total lunar eclipse of the last 12 months visible from the Americas and the Pacific region on the morning of April 4th…
The first eclipse of 2015 is coming right up on Friday, March 20th, and may provide a unique challenge for solar energy production across Europe.
Sure, we’ve been skeptical about many of the websites touting a ‘blackout’ and Y2K-like doom pertaining to the March 20th total solar eclipse as of late. And while it’s true that comets and eclipses really do bring out the ‘End of the World of the Week’ -types across ye ole web, there’s actually a fascinating story of science at the core of next week’s eclipse and the challenge it poses to energy production.
But first, a brief recap of the eclipse itself. Dubbed the “Equinox Eclipse,” totality only occurs over a swath of the North Atlantic and passes over distant Faroe and Svalbard Islands. Germany and central Europe can expect an approximately 80% partially obscured Sun at the eclipse’s maximum.
The magnitude of the March 20th solar eclipse across Europe. Credit: Michael Zeiler/GreatAmericanEclipse.com
We wrote a full guide with the specifics for observing this eclipse yesterday. But is there a cause for concern when it comes to energy production?
A power grid is a huge balancing act. As power production decreases from one source, other sources must be brought online to compensate. This is a major challenge — especially in terms of solar energy production.
Residential solar panels in Germany. Credit: Wikimedia Commons/ Sideka Solartechnik.
Germany currently stands at the forefront of solar energy technology, representing a whopping quarter of all solar energy capacity installed worldwide. Germany now relies of solar power for almost 7% of its annual electricity production, and during the sunniest hours, has used solar panels to satisfy up to 50% of the country’s power demand.
We recently caught up with Barry Fischer to discuss the issue. Fischer is the Head Writer at Opower, a software company that uses data to help electric and gas utilities improve their customer experience. Based on Opower’s partnerships with nearly 100 utilities worldwide, the company has amassed the world’s largest energy dataset of its kind which documents energy consumption patterns across more than 55 million households around the globe.
A study published last week by Opower highlights data from the partial solar eclipse last October over the western United States. There’s little historical precedent for the impact that an eclipse could have on the solar energy grid. For example, during the August 11th, 1999 total solar eclipse which crossed directly over Europe, less than 0.1% of utility electricity was generated using solar power.
Looking at the drop in power production during the October 2014 solar eclipse. Credit: Opower.
What they found was intriguing. Although the 2014 partial solar eclipse only obscured 30 to 50% of the Sun, solar electric production dropped over an afternoon span of nearly three hours before returning to a normal pattern.
Examining data from 5,000 solar-powered homes in the western United States, Opower found that during the eclipse those homes sent 41% less electricity back to the grid than normal. Along with a nearly 1,000 megawatt decline in utility-scale solar power production, these drop-offs were compensated for by grid operators ramping up traditional thermal power plants that were most likely fueled by natural gas.
No serious problems were experienced during the October 23rd, 2014 partial solar eclipse in terms of solar electricity production in the southwestern United States, though it is interesting to note that the impact of the eclipse on solar energy production could be readily detected and measured.
The projected effect of the March 20th eclipse on solar power production. Credit: Opower.
How does the drop and surge in solar power output anticipated for the March 20th eclipse differ from, say, the kind presented by the onset of night, or a cloudy day? “The impact of an eclipse can register broadly – and unusually rapidly – across an entire region,” Fischer told Universe Today. On a small scale, one area many be cloudy, while on a larger regional scale, other areas of clear or partly sunny skies can compensate. An eclipse — even a partial one — is fundamentally different, because the sudden onset and the conclusion are relatively uniform over a large region.
The March 20th event offers an unprecedented chance to study the effects of an eclipse on large-scale solar production up close. A study (in German) by the University of Applied Sciences in Berlin suggests that solar power production will fall at a rate 2.7 times faster than usual as the eclipse progresses over a span of 75 minutes. This is the equivalent of switching off one medium-sized power plant per minute.
The anticipated slingshot might be just as challenging, as 18 gigawatts of power comes back online at the conclusion of the eclipse in just over an hour. And as opposed to the 2014 eclipse over the U.S. which ended towards sunset, the key rebound period for the March 20th eclipse will be around local noon and during a peak production time.
Fischer also noted that “the second half of the partial solar eclipse will also pose a notable challenge” for the grid, as it is flooded with solar power production 3.5 times faster than normal. This phenomenon could also serve as a great model for what could occur daily on a grid that’s increasingly solar power reliant in the future, as energy production ramps up daily at sunrise. Such a reality may be only 15 years away, as Germany projects installed solar capacity to top 66 gigawatts by 2030.
The Crescent Dunes Solar Energy Project outside of Tonopah, Nevada. Credit: Wikimedia Commons/Amble. Licensed under a CC BY-SA 4.0 license.
This eclipse may serve as a great dry run for modeling what could occur as reliance on solar energy production grows.
Such is the modern technical society we live in. It’s fascinating to think that eclipses aren’t only a marvelous celestial spectacle, but their effects on power production may actually serve as a model for the smart grids of tomorrow.
The first of two eclipse seasons for the year is upon us this month, and kicks off with the only total solar eclipse for 2015 on Friday, March 20th.
And what a bizarre eclipse it is. Not only does this eclipse begin just 15 hours prior to the March equinox marking the beginning of astronomical spring in the northern hemisphere, but the shadow of totality also beats path through the high Arctic and ends over the North Pole.
An animation of the March 20th eclipse. Credit: NASA/GSFC/AT Sinclair.
Already, umbraphiles — those who chase eclipses — are converging on the two small tracts of terra firma where the umbra of the Moon makes landfall: the Faroe and Svalbard islands. All of Europe, the northern swath of the African continent, north-central Asia and the Middle East will see a partial solar eclipse, and the eclipse will be deeper percentage-wise the farther north you are .
2015 features four eclipses in all: two total lunars and two solars, with one total solar and one partial solar eclipse. Four is the minimum number of eclipses that can occur in a calendar year, and although North America misses out on the solar eclipse action this time ’round, most of the continent gets a front row seat to the two final total lunar eclipses of the ongoing tetrad on April 4th and September 28th.
How rare is a total solar eclipse on the vernal equinox? Well, the last total solar eclipse on the March equinox occurred back in 1662 on March 20th. There was also a hybrid eclipse — an eclipse which was annular along a portion of the track, and total along another — on March 20th, 1681. But you won’t have to wait that long for the next, as another eclipse falls on the northward equinox on March 20th, 2034.
The path of the March 20th eclipse across Europe, including start times for the partial phases, and the path of totality, click to enlarge. For more maps showing the percentage of occlusion, elevation, and more, click here. Credit: Michael Zeiler/GreatAmercianEclipse.com.
Note that in the 21st century, the March equinox falls on March 20th, and will start occasionally falling on March 19th in 2044. We’re also in that wacky time of year where North America has shifted back to ye ‘ole Daylight Saving (or Summer) Time, while Europe makes the change after the eclipse on March 29th. It really can wreak havoc with those cross-time zone plans, we know…
The March 20th eclipse also occurs only a day after lunar perigee, which falls on March 19th at 19:39 UT. This is also one of the closer lunar perigees for 2015 at 357,583 kilometres distant, though the maximum duration of totality for this eclipse is only 2 minutes and 47 seconds just northeast of the Faroe Islands.
Views from selected locales in Europe and Africa. Credit: Stellarium.
This eclipse is number 61 of 71 in solar saros series 120, which runs from 933 to 2754 AD. It’s also the second to last total in the series, with the final total solar eclipse for the saros cycle occurring one saros later on March 30th, 2033.
And speaking of obscure eclipse terminology, check out this neat compendium we came across in research. What’s an Exeligmos? How many Heptons are in a Gregoriana?
The 462 kilometre wide path of the eclipse touches down south of Greenland at 9:13 UT at sunrise, before racing across the North Atlantic towards the pole and departing the Earth at 10:21 UT. The sedate partial phases for the eclipse worldwide start at 7:40 UT, and run out to 11:51 UT.
What would it look like to sit at the North Pole and watch a total solar eclipse on the first day of Spring? It would be a remarkable sight, as the disk of the Sun skims just above the horizon for the first time since the September 2014 equinox. Does this eclipse occur at sunrise or sunset as seen from the pole? It would be a rare spectacle indeed!
An equinoctal eclipse as simulated from the North Pole. Credit: Stellarium.
Alas, this unique view from the pole will more than likely go undocumented. A similar eclipse was caught in 2003 from the Antarctic, and a few intrepid eclipse chasers, including author David Levy did manage to make the journey down under to witness totality from the polar continent.
Practicing eclipse safety in Africa. Credit: Michael Zeiler/GreatAmericanEclipse.com
Safety is paramount when observing the Sun and a solar eclipse. Eye protection is mandatory during all partial phases across Europe, northern Asia, North Africa and the Middle East. A proper solar filter mask constructed of Baader safety film is easy to construct, and should fit snugly over the front aperture of a telescope. No. 14 welder’s goggles are also dense enough to look at the Sun, as are safety glasses specifically designed for eclipse viewing. Observing the Sun via projection or by using a pinhole projector is safe and easy to do.
A solar filtered scope ready to go in Tucson, Arizona. Credit: photo by author.
Weather is always the big variable in the days leading up to any eclipse. Unfortunately, March in the North Atlantic typically hosts stormy skies, and the low elevation of the eclipse in the sky may hamper observations as well. From the Faroe Islands, the Sun sits 18 degrees above the horizon during totality, while from the Svalbard Islands it’s even lower at 12 degrees in elevation. Much of Svalbard is also mountainous, making for sunless pockets of terrain that will be masked in shadow on eclipse day. Mean cloud amounts for both locales run in the 70% range, and the Eclipser website hosts a great in-depth climatology discussion for this and every eclipse.
The view of totality and the planets as seen from the Faroe Islands. Credit: Starry Night.
But don’t despair: you only need a clear view of the Sun to witness an eclipse!
Solar activity is also another big variable. Witnesses to the October 23rd, 2014 partial solar eclipse over the U.S. southwest will recall that we had a massive and very photogenic sunspot turned Earthward at the time. The Sun has been remarkably calm as of late, though active sunspot region 2297 is developing nicely. It will have rotated to the solar limb come eclipse day, and we should have a good grasp on what solar activity during the eclipse will look like come early next week.
And speaking of which: could an auroral display be in the cards for those brief few minutes of totality? It’s not out of the question, assuming the Sun cooperates. Of course, the pearly white corona of the Sun still gives off a considerable amount of light during totality, equal to about half the brightness of a Full Moon. Still, witnessing two of nature’s grandest spectacles — a total solar eclipse and the aurora borealis — simultaneously would be an unforgettable sight, and to our knowledge, has never been documented!
We also put together some simulations of the eclipse as seen from Earth and space:
Note that an area of southern Spain may witness a transit of the International Space Station during the partial phase of the eclipse. This projection is tentative, as the orbit of the ISS evolves over time. Be sure to check CALSky for accurate predictions in the days leading up to the eclipse.
The ISS transits the Sun during the eclipse around 9:05 UT as seen from southern Spain. Credit: Starry Night.
Can’t make it to the eclipse? Live in the wrong hemisphere? There are already a few planned webcasts for the March 20th eclipse:
–Astronomia Practica plans to post photos in near real time of the eclipse from northern Scotland.
And stay tuned, as North America and the Pacific region will witness another total lunar eclipse on April 4th 2015. And we’ve only got one more total solar eclipse across Southeast Asia in 2016 before the total solar eclipse of August 21st 2017 spanning the U.S.
Let the first eclipse season of 2015 begin!
Next… how will the solar eclipse affect the European solar grid? Expect an article on just that soon!
Be sure to send those eclipse pics in to Universe Today.
Supermoons. Blood Moons. Moons both Black and Blue… by now, you’d think that there was nothing new under the Sun (or Moon, as it were) when it comes to new unofficial lunar terminology.
Sure, the Moon now seems more colorful than controversial viral dress shades. Love it or loathe it, the Internet can sure set a meme in motion. And this week’s Full Moon on Thursday evening offers up one of our faves, as the most distant Full Moon of 2015 occurs on March 5th. Yup, the Mini-Moon is indeed once again upon us, a time when the Full Moon appears slightly smaller than usual as seen from the Earth. But can you really tell the difference?
The third Full Moon of the year occurs this week on Thursday, March 5th. Also known as the Worm or Sap Moon by the Algonquin tribes of New England, the moment of Full phase occurs at 18:07 Universal Time (UT) or 1:07 PM Eastern Standard Time (EST). This is also just over 10 hours after apogee, which occurs at 7:36 UT/2:36 AM EST. This month’s apogee is also an exceptionally distant one, measuring 406,385 kilometres from the center of the Earth to the center of the Moon. This is just 80 kilometres shy of the most distant apogee of 2015 on September 14th, which occurs when the Moon is near New phase.
Can you spy Jupiter next to the waxing gibbous Moon before sunset tonite? Credit: Stellarium.
Apogee for the Moon ranges from 404,000 to 406,700 kilometres distant, and the Full Moon appears 29.3 arc minutes across near apogee versus 34.1’ across near perigee as seen from the Earth.
This is also the closest apogee near a Full Moon time-wise until January 27th, 2032.
What is a Mini-Moon? As with a Supermoon, we prefer simply defining a Mini-Moon as a Full Moon which occurs within 24 hours of apogee. That’s much more definitive in our book rather than the cryptic and often cited ‘within 90% of its orbit’ refrain for Supermoons.
And speaking of which, we’ve got three ‘Super’ Full Moons in 2015, with the very closest Super (Duper?) Full Moon occurring within an hour of perigee on September 28th during the final total lunar eclipse of the ongoing tetrad… what will the spin doctors of the Internet make of this? A ‘Super Duper Blood Moon,’ anyone?
The path of the Moon this week also takes it towards the Fall equinoctial point in the astronomical constellation of Virgo, as it crosses Leo and nicks the corner of the non-zodiacal constellation Sextans. The Moon reaches Full two weeks prior to the Vernal Equinox, which falls this year on March 20th. Keep an eye on the Moon, as the first eclipse of 2015 and this year’s only total solar eclipse also occurs just 13 hours prior to the equinox for observers in the high Arctic. (More on that next week).
Can’t wait til Thursday? Tonight, observers across Canada, northern Maine, and Europe will see a fine occultation of the star Acubens (a.k.a. Alpha Cancri) by the 94% illuminated waxing gibbous Moon:
The ‘shadow footprint’ for tonight’s occultation of Acubens by the Moon. Credit: Occult 4.0.1.
Alpha Cancri is 175 light years distant, and folks living along the U.S./Canadian border will be treated to a fine grazing occultation as the double star plays hide and seek along the limb of the Moon. This is number 17 in an ongoing series of 21 occultations of the star by the Moon stretching out until June 20th, 2015. There’s a wide separation of 11” between the star’s A and B components, and there are suspicions from previous lunar occultations that Alpha Cancri A may itself be a double star as well.
We caught a similar occultation of the star Lambda Geminorum by the Moon this past Friday:
Ever feel sorry for moonless Venus? This Wednesday night also offers a chance to spy Venus with a brief ‘pseudo-moon,’ as +6th magnitude Uranus passes just 15’ — less than half the apparent diameter of a Full Moon — from brilliant -4th magnitude Venus. Neith, the spurious 18th century moon of Venus lives! From the vantage point of Venus on March 4th, the Earth and Moon would shine at magnitudes -2.3 and +1.5, respectively, and sit about 4 arc minutes apart.
The rising Full ‘Mini-Moon’ of March 5th. Credit: Starry Night Education Software.
Does the rising Full Moon look smaller to you than usual this week? While the apparent change in diameter from apogee to perigee is slight, it is indeed noticeable to the naked eye observers. Remember, the Moon is actually about one Earth radius (6,400 kilometres) more distant on the local horizon than when it’s directly overhead at the zenith. The Moon is also moving away from us at a current rate of 1-2 centimetres a year, meaning that Mini-Moons will get ever more distant in epochs hence.
Already, annular solar eclipses are currently more common than total ones by a ratio of about 11 to 9. The first annular eclipse as seen from the Earth went unheralded some time about 900 million to a billion years ago, and 1.4 billion years hence, the last total solar eclipse will occur.
The rising waxing gibbous Moon against the daytime sky. Photo by author.
Be sure to get out and enjoy the rising Mini-Moon later this week!
Did you hear the one about last month’s ‘supermoon?’
Yeah, we know. The hype was actually for an event that was less than spectacular, as it revolved around the first New Moon of 2015 on January 20th. Said suspect Moon was touted as ‘super’ (we prefer the quixotic term proxigean) as it occurred 18 hours prior to perigee.
Not that the first lunar perigee of 2015 was an especially close one in time or space at 359,642 kilometres distant. Is every New and Full Moon now destined to become branded ‘super’ in the never ending SEO quest to get eyeballs on web pages?
But wait, there’s more. We’ve noticed as of late that another popular term is creeping into the popular astronomical vernacular: that of a ‘Black Moon’.
Black Moons for the next decade. Created by the author.
We’ve written lots about Moons both of the Black and Blue variety before. We’ll also let you in on a small secret: astronomers rarely sit around observatories discussing these Moons, be they Blue, Black or Super. At most, astronomers note the weeks surrounding New as the ‘Dark of the Moon,’ a prime time to go deep for faint objects while the light polluting Moon is safely out of the sky. And yes, terms such as ‘Super’ or ‘Black Moon’ have dubious roots in astrology, while the term Blue Moon comes down to us via a curious mix-up from Sky and Telescope and the Maine Farmer’s Almanac.
Simply put, a Black Moon is the New Moon version of a Blue Moon, and is either:
A month missing a Full or New Moon… this can only occur in February, as the lunar synodic period from like phase to phase is 29.5 days long. This last occurred in 2014 and will next occur in 2018.
The second New Moon in a month with two. This can happen in any calendar month except February.
And now for the most convoluted definition: the third New Moon in an astronomical season with four.
We bring this up because the February 18th New Moon is ‘Black’ in the sense that it meets the requirements expressed in rule 3. The fourth New Moon of the season falls on March 20th, just 13 hours before the northward equinox on the same date.
An extremely thin crescent Moon against a low contrast twilight sky. Credit and copyright: David Blanchflower.
Such are the curious vagaries of the juxtaposition of the lunar cycle on our modern day Gregorian calendar. Unfortunately, this doesn’t mean you’ll win the lottery or be lucky in love: any Earthly woes are strictly your own affairs to deal with, Black Moon or no. Continue reading “Black Moon: Why the New Moon on February 18th is Special”
The Moon passes Mars and Venus last month... this week's pass is much closer! (Photo by Author).
Fear not, the chill of late February. This Friday gives lovers of the sky a reason to brave the cold and look westward for a spectacular close triple conjunction of the planets Mars, Venus and the waxing crescent Moon.
This week’s New Moon is auspicious for several reasons. We discussed the vagaries of the Black Moon of February 2015 last week, and the lunacy surrounding the proliferation of the perigee supermoon. And Happy ‘Year of the Goat’ as reckoned on the Chinese luni-solar calendar, as this week’s New Moon marks the start of the Chinese New Year on February 19th. Or do you say Ram or Sheep? Technical timing for the New Moon is on Wednesday, February 18th at 23:47 UT/6:47 PM EST, marking the start of lunation 1140. The next New Moon on March 20th sees the start of the first of two eclipse seasons for 2015, with a total solar eclipse for the high Arctic. More on that next month! Continue reading “Catch a ‘Conjunction Triple Play’ on February 20th as the Moon Meets Venus & Mars”
Play the skywatching game long enough, and anything can happen.
Well, nearly anything. One of the more unique clockwork events in our solar system occurs this weekend, when shadows cast by three of Jupiter’s moons can be seen transiting its lofty cloud tops… simultaneously.
How rare is such an event? Well, Jean Meeus calculates 31 triple events involving moons or their shadows occurring over the 60 year span from 1981 to 2040.
But not all are as favorably placed as this weekend’s event. First, Jupiter heads towards opposition just next month. And of the aforementioned 31 events, only 9 are triple shadow transits. Miss this weekend’s event, and you’ll have to wait until March 20th, 2032 for the next triple shadow transit to occur.
Hubble spies a triple shadow transit on March 28th, 2004 . Credit: NASA/JPL/Arizona.
Of course, double shadow transits are much more common throughout the year, and we included some of the best for North America and Europe in 2015 in our 2015 roundup.
The key times when all three shadows can be seen crossing Jupiter’s 45” wide disk are on the morning of Saturday, January 24th starting at 6:26 Universal Time (UT) as Europa’s shadow ingresses into view, until 6:54 UT when Io’s shadow egresses out of sight. This converts to 1:26 AM EST to 1:54 AM EST. The span of ‘triplicate shadows’ only covers a period of slightly less than 30 minutes, but the action always unfolds fast in the Jovian system with the planet’s 10 hour rotation period.
The view on January 24th at 6:41 UT/1:41 AM EST. Credit: Created using Starry Night Education software.
Unfortunately, the Great Red Spot is predicted to be just out of view when the triple transit occurs, as it crosses Jupiter’s central meridian over three hours later at 10:28 UT.
The moons involved in this weekend’s event are Io, Callisto and Europa. Now, I know what you’re thinking. Seeing three shadows at once is pretty neat, but can you ever see four?
The short answer is no, and the reason has to do with orbital resonance.
The orbital resonance of the three innermost Galilean moons. (Credit: Wikimedia Commons).
The three innermost Galilean moons of Jupiter (Io, Europa and Ganymede) are locked in a 4:2:1 resonance. Unfortunately, this resonance assures that you’ll always see two of the innermost three crossing the disk of Jupiter, but never all three at once. Either Europa or Ganymede is nearly always the “odd moon out.”
To complete a ‘triple play,’ outermost Callisto must enter the picture. Trouble is, Callisto is the only Galilean moon that can ‘miss’ Jupiter’s disk from our line of sight. We’re lucky to be in an ongoing season of Callisto transits in 2015, a period that ends in July 2016.
Perhaps, on some far off day, a space tourism agency will offer tours to that imaginary vantage point on the surface of one of Jupiter’s moons such as Callisto to watch a triple transit occur from close up. Sign me up!
Jupiter currently rises in late January around 5:30 PM local, and sets after sunrise. It is also well placed for northern hemisphere observers in Leo at a declination 16 degrees north . This weekend’s event favors Europe towards local sunrise and ‘Jupiter-set,’ and finds the gas giant world well-placed high in the sky for all of North America in the early morning hours of the 24th.
Jupiter rides high to the south at 1:45 AM EST for the US East Coast. Credit: Stellarium.
Look closely. Do the shadows of the individual moons appear different to you at the eyepiece? It’s interesting to note during a multiple transit that not all Jovian moon shadows are ‘created equal’. Distant Callisto casts a shadow that’s broad, with a ragged gray and diffuse rim, while the shadow of innermost Io appears as an inky black punch-hole dot. If you didn’t know better, you’d think those alien monoliths were busy consuming Jupiter in a scene straight out of the movie 2010. Try sketching multiple shadow transits and you’ll soon find that you can actually identify which moon is casting a shadow just from its appearance alone.
The orientation of Earth’s nighttime shadow at mid-triple transit. Credit: Created using Orbitron.
Other mysteries of the Galilean moons persist as well. Why did late 19th century observers describe them as egg-shaped? Can visual observers tease out such elusive phenomena as eruptions on Io by measuring its anomalous brightening? I still think it’s amazing that webcam imagers can now actually pry out surface detail from the Galilean moons!
The 2004 triple shadow transit. Photo by author.
Observing and imaging a shadow transit is easy using a homemade planetary webcam. We’d love to see someone produce a high quality animation of the upcoming triple shadow transit. I know that such high tech processing abilities — to include field de-rotation and convolution mapping of the Jovian sphere — are indeed out there… its breathtaking to imagine just how quickly the fledgling field of ad hoc planetary webcam imaging has changed in just 10 years.
The moons and Jupiter itself also cast shadows off to one side of the planet or the other depending on our current vantage point. We call the point when Jupiter sits 90 degrees east or west of the Sun quadrature, and the point when it rises and sets opposite to the Sun is known as opposition. Opposition for Jupiter is coming right up for 2015 on February 6th. During opposition, Jupiter and its moons cast their respective shadows nearly straight back.
Did you know: the speed of light was first deduced by Danish astronomer Ole Rømer in 1671 using the discrepancy he noted while predicting phenomena of the Galilean moons at quadrature versus opposition. There were also early ideas to use the positions of the Galilean moons to tell time at sea, but it turned out to be hard enough to see the moons and their shadows with a small telescope based on land, let alone from the pitching deck of a ship in the middle of the ocean.
And speaking of mutual events, we’re still in the midst of a season where it’s possible to see the moons of Jupiter eclipse and occult one another. Check out the USNO’s table for a complete list of events, coming to a sky near you.
And let’s not forget that NASA’s Juno spacecraft is headed towards Jupiter as well., Juno is set to enter a wide swooping orbit around the largest planet in the solar system in July 2016.
Now is a great time to get out and explore Jove… don’t miss this weekend’s triple shadow transit!
Read Dave Dickinson’s sci-fi tale of astronomical eclipse tourism through time and space titled Exeligmos.
This artist’s impression shows an eclipsing binary star system. Credit: ESO/L. Calçada.
Update: It’s off. This past weekend, the AAVSO issued Special Notice #395 calling off the campaign to observe Alpha Comae Berenices this month due to “position measurements published a century ago (which) contained errors that affected the predictions for the time of eclipse…”
And the mystery of Alpha Comae Berenices continues. Oh well. Such is the wiles and whims of the universe, and the exciting field of variable star observing!
A truly fascinating event may be in the offing this month.
Picture two distant burning embers (candles, light bulbs, LEDs, what have you) circling each other in the distance. From our far-flung vantage point, the two points of light are too faint to resolve individually, but as they pass in front of each other, a telltale dip in combined brightness occurs as one blocks out the other.
Welcome to the fascinating world of eclipsing binary stars. This week, we’d like to turn our attention towards a special star in the constellation of Coma Berenices which may — or may not — put on such a dimming act later this month.
An Alpha Comae Berenices (Diadem) finder chart, with comparison stars and magnitudes, decimals omitted. Credit: Starry Night Education Software.
The brightest star in the constellation Coma Berenices, Alpha (sometimes referred to as Diadem, or the ‘crown’ of Queen Berenice) shines at an apparent magnitude of +4.3. Located 63 light years distant, the system consists of two +5th magnitude F-type stars each about 3 times more luminous than our Sun locked in a 26 year orbital embrace. The physical separation of the pair is about 10 astronomical units: place Alpha Comae Berenices in our solar system, and the pair would fit nicely between the Sun and Saturn.
The orbital plane of the pair is inclined nearly along our line of sight as seen from the Earth, and it’s long been thought that catching a grazing or central eclipse of the pair might just be possible. No eclipse was recorded last time ‘round back in February 1989, but times have changed lots in observational astronomy. Today, there are enough backyard observers armed with dedicated observatories and rigs that’d be the envy of a small university that documenting such an eclipse might just be possible. In fact, a central eclipse might just dim the star by 0.8 magnitudes, and should be noticeable to the naked eye.
The binary nature of Alpha Comae Berenices was first noted by F. G. W. Struve in 1827, and the split is a challenging one during the best of years with a maximum angular separation of just 0.7 arc seconds. The pair also has a third faint +10th magnitude companion located about 89 arc seconds away.
A simplified diagram depicting an eclipsing binary event along our line of sight. Created by the author.
The American Association of Variable Star Observers (AAVSO) has an Alert Notice calling for sky watchers worldwide to monitor the star. We also understand the orbit of Alpha Comae Berenices much better in 2015 than back in 1989, and the suspected eclipse should occur somewhere between January 22nd and January 28th and may last anywhere from 28 to 45 hours. This lingering ambiguity means that having a dedicated team of observers worldwide may well be key to nabbing this eclipse.
Alpha Comae Berenices rising. Photo by the author.
The Navy Precision Optical Interferometer (NPOI) has already begun refining measurements of the brightness of the star last month, and professional facilities, to include the Fairborn Observatory atop Mt Hopkins in Arizona and the CHARA (the Center for High Angular Resolution Astronomy) Array at Mount Wilson Observatory in southern California will also be monitoring the event.
Sky and Telescope magazine also has an excellent article in their January 2015 issue on the prospects for catching this eclipse.
Looking eastward past local midnight. Credit: Stellarium.
In late January, the constellation of Coma Berenices rises high to the northeast just after local midnight. It’s worth noting that, if the eclipsing binary nature of Alpha Comae Berenices is confirmed, it would be the longest period known, beating out 14.6 year Gamma Persei discovered in 1990 by more than a decade. A system with as wide a separation as Alpha Comae Berenices would have about a 1 in 1,200 chance in eclipsing along our line of sight due to random chance.
Note: Epsilon Aurigae does have a comparable 27 year period involving a debris disk surrounding its host star. Thanks to sharp-eyed reader Dr. John Barentine for pointing this out!
Of course, the universe does provide us with lots of near misses, allowing for an ‘occasional Diadem’ to indeed occur. Most famous eclipsing variables, such as Algol or Beta Lyrae have periods measured over the span of days or hours. Incidentally, these also make great ‘practice stars’ to test your skills as a visual athlete leading up to the big event next week. A skilled visual observer can note a change as slight as a 0.1 of a magnitude, and it’s a good idea to begin familiarizing yourself with the environs of the star now. The Coma Cluster of galaxies, the globular cluster M53, and the galactic plane crossing intruder Arcturus all lie nearby.
The Coma Cluster as seen by Spitzer Space Telescope and the Sloan Digital Sky Survey. Credit: NASA/Spitzer.
Why study eclipsing binaries? Well, said fleeting mutual events when coupled with spectroscopic measurements and determinations of parallax can tell us a good deal about the astrophysical nature of the stars involved. Eclipsing binary stars have even been used to back up standard candle measurements over extragalactic distances. And of course, orbiting observatories such as Kepler and TESS (to be launched in 2017) look for transiting exoplanets using virtually the same method.
Have a scope+DSLR? Then you can make refined measurements of eclipsing variable stars. Credit: Brad Timerson/IOTA.
But beyond its practical application, we just think that it’s plain cool that you can actually see something out beyond our solar system changing in the span of just a few days or hours.
Observers also still carry out visual observations of variable stars, just like those pipe-smoking, pocket watch carrying astronomers of yore. This involves merely comparing the target star to nearby stars of the same brightness. If you have a DSLR or a CCD rig plus a telescope, the AAVSO also has instructions for how to monitor a star’s brightness as well. No pocket watch required.
A homemade ‘card interferometer’ used to measure the separation of close double stars. Photo by author.
Unless, of course, you want to carry a pocket watch just for good luck. Don’t let the cold January winters keep you from joining the hunt. Let’s make some astrophysical history!
Now in its seventh year of compilation and the second year running on Universe Today, we’re proud to feature our list of astronomical happenings for the coming year. Print it, bookmark it, hang it on your fridge or observatory wall. Not only is this the yearly article that we jokingly refer to as the “blog post it takes us six months to write,” but we like to think of it as unique, a mix of the mandatory, the predictable and the bizarre. It’s not a 10 ten listicle, and not a full-fledged almanac, but something in between.
A rundown of astronomy for 2015: There’s lots of astronomical action to look forward to in the coming year. 2015 features the minimum number of eclipses that can occur, two lunars and two solars. The Moon also reaches its minimum standstill this coming year, as its orbit runs shallow relative to the celestial equator. The Moon will also occult all naked eye planets except Saturn in 2015, and will occult the bright star Aldebaran 13 times — once during every lunation in 2015. And speaking of Saturn, the rings of the distant planet are tilted an average of 24 degrees and opening to our line of sight in 2015 as they head towards their widest in 2018.
Finally, solar activity is trending downwards in 2015 after passing the sputtering 2014 maximum for solar cycle #24 as we now head towards a solar minimum around 2020.
Our best bets: Don’t miss these fine celestial spectacles coming to a sky near YOU next year:
– The two final total lunar eclipses in the ongoing tetrad, one on April 4th and September 28th.
– The only total solar eclipse of 2015 on March 20th, crossing the high Arctic.
– A fine dusk pairing of the bright planets Jupiter and Venus on July 1st.
– Possible wildcard outbursts from the Alpha Monocerotid and Taurid meteors, and a favorable New Moon near the peak of the August Perseids.
– Possible naked eye appearances by comet Q2 Lovejoy opening 2015 and comet US10 Catalina later in the year.
– The occultation of a naked eye star for Miami by an asteroid on September 3rd.
– A series of fine occultations by the Moon of bright star Aldebaran worldwide.
The rules: The comprehensive list that follows has been lovingly distilled down to the top 101 astronomical events for 2015 worldwide. Some, such as lunar eclipses, are visible to a wide swath of humanity, while others, such as many of the asteroid occultations or the sole total solar eclipse of 2015 happen over remote locales. We whittled the list down to a “Top 101” using the following criterion:
Meteor showers: Must have a predicted ZHR greater than 10.
Conjunctions: Must be closer than one degree.
Asteroid occultations: Must have a probability ranking better than 90 and occult a star brighter than magnitude +8.
Comets: Must reach a predicted brightness greater than magnitude +10. But remember: comets don’t always read prognostications such as this, and may over or under perform at whim… and the next big one could come by at any time!
Times quoted are geocentric unless otherwise noted, and are quoted in Universal Time in a 24- hour clock format.
These events are meant to merely whet the appetite. Expect ‘em to be expounded on fully by Universe Today as they approach. We linked to the events listed where possible, and provided a handy list of resources that we routinely consult at the end of the article.
Got it? Good… then without further fanfare, here’s the top 101 astronomical events for 2015 in chronological order:
The path of Comet Q2 Lovejoy from January 1st to January 31st. Created using Starry Night Education software.
29- The Moon occults Aldebaran at ~17:31 UT for the Arctic, marking the first of 13 occultations of the star by the Moon in 2015.
The view at 6:40 UT on January 24th, as 3 of Jupiter’s moons cast shadows on to the Jovian cloud tops simultaneously. Created using Starry Night Education software.
February
01- Venus passes 0.8 degrees south of Neptune at ~17:00 UT.
05- Earth crosses through Jupiter’s equatorial plane, marking the middle of occultation and eclipse season for the Galilean moons.
06- Jupiter reaches opposition at ~18:00 UT.
18- A “Black Moon” occurs, in the sense of the third New Moon in a season with four.
22- Venus passes 0.4 degrees south of Mars at 5:00 UT.
24- Mercury reaches greatest morning elongation at 26.7 degrees west of the Sun at 19:00 UT.
21- Io and Ganymede both cast shadows on Jupiter from 00:04 to 00:33 UT.
21- Callisto and Europa both cast shadows on Jupiter from 13:26 to 13:59 UT.
23- Saturn reaches opposition at ~1:00 UT.
24- Asteroid 1669 Dagmar occults the +1st magnitude star Regulus at ~16:47 UT for the Arabian peninsula,
the brightest star occulted by an asteroid for 2015.
28- Ganymede and Io both cast shadows on Jupiter from 02:01 to 04:18 UT.
30- Comet 19P/Borrelly may reach binocular visibility.
June
01- The International Space Station reaches full illumination as the June solstice nears, resulting in multiple nightly passes favoring northern hemisphere observers.
04- Io and Ganymede both cast shadows on Jupiter from 4:54 to 6:13 UT.
05- Venus reaches greatest eastern (dusk) elongation for 2015, 45 degrees from the Sun at 16:00 UT.
10- Asteroid 424 Gratia occults a +6.1 magnitude star at ~15:10 UT for northwestern Australia.
13- The Perseid meteors peak from 06:30 to 09:00 UT, with a maximum predicted ZHR of 100 favoring North America.
19- Mars crosses the Beehive Cluster M44.
28- Asteroid 16 Psyche occults a +6.4 magnitude star at ~9:49 UT for Bolivia and Peru.
29- Supermoon 1 of 3 for 2015: The Moon reaches Full at 18:38 UT, 20 hours from perigee.
The path of the Moon through the Earth’s shadow on September 28th. Credit: Fred Espenak/NASA/GSFC
September
01- Neptune reaches opposition at ~3:00 UT.
03- Asteroid 112 Iphigenia occults a +3rd magnitude star for Mexico and Miami at ~9:20 UT. This is the brightest star occulted by an asteroid in 2015 for North America.
02- Geostationary satellite and SDO eclipse season begins as we approach the September equinox.
04- Mercury reaches its greatest elongation for 2015, at 27 degrees east of the Sun at 8:00 UT in the dusk skies.
05- The Moon occults Aldebaran for northeastern North America at ~5:38 UT.
13- “Shallow point” (also known as the minor lunar standstill) occurs over the next lunation, as the Moon’s orbit reaches a shallow minimum of 18.1 degrees inclination with respect to the celestial equator… the path of the Moon now begins to widen towards 2025.
13- A partial solar eclipse occurs, centered on 6:55 UT crossing Africa and the Indian Ocean.
25- Mars passes 0.8 degrees from Regulus at ~4:00 UT.
28- A total lunar eclipse occurs centered on 2:48 UT, visible from the Pacific, the Americas and eastern Europe.
28- Supermoon 2 of 3 for 2015: The Moon reaches Full at 2:52 UT, approximately an hour from perigee. This marks the closest Full Moon of the year.
The path of the September 3rd occultation of a +3rd magnitude star by an asteroid over central Mexico and the Florida Keys. Credit: IOTA/Steve Preston.
The Moon occults Aldebaran: the visibility footprint for North America. The dashed line denotes the area in which the event occurs during the daytime. Credit: Occult 4.1.0.11.
November
01- Io and Ganymede both cast shadows on Jupiter from 17:36 to 17:47 UT.
02- Venus passes 0.7 degrees south of Mars at 00:30 UT.
12- Will the 7 year “Taurid fireball meteor shower” produce?
18- The Leonid meteor shower peaks at 04:00 UT, with an estimated ZHR of 15 favoring Europe.
22- Are we in for a once per decade Alpha Monocerotids outburst? The 2015 peak arrives at 4:25 UT, favoring Europe… with a max ZHR = 400+ possible.
The daytime occultation of Venus by the Moon over North America on December 7th.Credit: Occult 4.1.0.11.
December
01- The International Space Station reaches full illumination as the December solstice nears, resulting in multiple nightly passes favoring the southern hemisphere.
04- Mercury occults the +3.3 magnitude star Theta Ophiuchi for South Africa at 16:16 UT prior to dusk.
06- The Moon occults Mars for central Africa at ~2:42 UT.
07- The Moon occults Venus in the daytime for North America at ~16:55 UT.
14- The Geminid meteor shower peaks at 18:00 UT, with a ZHR=120 favoring NE Asia.
The total solar eclipse of November 2012 as seen from
Where will YOU be on August 21st, 2017?
Astronomy is all about humility and thinking big in terms of space and time. It’s routine for astronomers to talk of comets on thousand year orbits, or stars with life spans measured in billions of years…
Yup, the lifespan of your average humanoid is indeed fleeting, and pales in comparison to the universe, that’s for sure. But one astronomical series that you can hope to live through is the cycle of eclipses.
I remember reading about the total solar eclipse of February 26th, 1979 as a kid. Carter was in the White House, KISS was mounting yet another comeback, and Voyager 1 was wowing us with images of Jupiter. That was also the last total solar eclipse to grace mainland United States in the 20th century.
But the ongoing “eclipse-drought” is about to be broken.
One thousand days from this coming Monday, November 24th on August 21st 2017, the shadow of the Moon will touch down off of the Oregon coast and sweep eastward across the U.S. heartland before heading out to the Atlantic off of the coast of South Carolina. Millions live within a days’ drive of the 115 kilometre wide path, and the eclipse has the added plus of occurring at the tail end of summer vacation season. This also means that lots of folks will be camping and otherwise mobile with their RVs and able to journey to the event.
This is also the last total solar eclipse to pass over any of the 50 United States since July 11th, 1991, and the first eclipse to cross the contiguous United States from “sea to shining sea” since way back on June 8th, 1918.
Think it’s too early to prepare? Towns across the path, including Hopkinsville, Kentucky and towns in Kansas and Nebraska are already laying plans for eclipse day. Other major U.S. cities, such as Nashville, Idaho Falls, and Columbia, South Carolina also lie along the path of totality, and the spectacle promises to spawn a whole new generation of “umbraphiles” or eclipse chasers.
A total solar eclipse is an unforgettable sight. But unlike a total lunar eclipse, which can be viewed from the moonward-facing hemisphere of the Earth, one generally has to journey to the narrow path of totality to see a total solar eclipse. Totality rarely comes to you.
The Zeilers view the November 2013 eclipse from Africa. Credit: Michael Zeiler.
And don’t settle for a 99% partial eclipse just outside the path. “There’s no comparison between partial and total solar eclipses when it comes to sheer grandeur and beauty,” Michael Zeiler, longtime eclipse chaser and creator of the Great American Eclipse website told Universe Today. We witnessed the 1994 annular solar eclipse of the Sun from the shores of Lake Erie, and can attest that a 99% partial eclipse is still pretty darned bright!
There are two total solar eclipses remaining worldwide up until 2017: One on March 20th, 2015 crossing the high Arctic, and another on March 9th 2016 over Southeast Asia. The 2017 eclipse offers a maximum of 2 minutes and 41 seconds of totality, and weather prospects for the eclipse in late August favors viewers along the northwestern portion of the track.
And though an armada of cameras will be prepared to capture the eclipse along its trek across the U.S., many veteran eclipse chasers suggest that first time viewers merely sit back and take in the moment. The onset of totality sees a bizarre sort of twilight fall across the landscape, as shadow bands skip across the countryside, temperatures drop, and wildlife is fooled into thinking that nightfall has come early.
And then, all too soon, the second set of blinding diamond rings burst through the lunar valleys, the eclipse glasses go back on, and totality is over. Which always raises the question heard throughout the crowd post-eclipse:
When’s the next one?
Well, the good news is, the United States will host a second total solar eclipse on April 8th, 2024, just seven years later! This path will run from the U.S. Southwest to New England, and crisscross the 2017 path right around Carbondale, Illinois.
Will the woo that surfaced around the approach of Comet ISON and the lunar tetrad of “blood Moon eclipses” rear its head in 2017? Ah, eclipses and comets seem to bring ‘em out of the woodwork, and 2017 will likely see a spike in the talking-head gloom and doom videos ala YouTube. Some will no doubt cite the “perfection” seen during total solar eclipses as proof of divine inspiration, though this is actually just a product of our vantage point in time and space. In fact, annular eclipses are slightly more common than total solars in our current epoch, and will become more so as the Moon slowly recedes from the Earth. And we recently noted in our post on the mutual phenomena of Jupiter’s moons that solar eclipses very similar to those seen from the Earth can also be spied from Callisto.
Heads up to any future interplanetary eclipse resort developer: Callisto is prime real estate.
