See a Flirtatious Lunar Eclipse This Friday Night

This sequence of photos taken on October 18, 2013 nicely show the different phases of a penumbral lunar eclipse. The coming penumbral eclipse will likely appear even darker because Earth’s shadow will shade to the top (northern) half of the Moon rich in dark lunar “seas” at maximum. Credit: AstroTripper 2000

Not many people get excited about a penumbral eclipse, but when it’s a deep one and the only lunar eclipse visible in North America this year, it’s worth a closer look. What’s more, this Friday’s eclipse happens during convenient, early-evening viewing hours. No getting up in the raw hours before dawn.

Lunar eclipses — penumbral, partial and total — always occur at Full Moon, when the Moon, Earth and Sun line up squarely in a row in that order. Only then does the Moon pass through the shadow cast by our planet. Credit: Starry Night with additions by the author

During a partial or total lunar eclipse, the full moon passes first through the Earth’s outer shadow, called the penumbra, before entering the dark, interior shadow or umbra. The penumbra is nowhere near as dark as the inner shadow because varying amounts of direct sunlight filter into it, diluting its duskiness.

To better understand this, picture yourself watching the eclipse from the center of the Moon’s disk (latitude 0°, longitude 0°). As you look past the Earth toward the Sun, you would see the Sun gradually covered or eclipsed by the Earth. Less sunlight would be available to illuminate the Moon, so your friends back on Earth would notice a gradual dimming of the Moon, very subtle at first but becoming more noticeable as the eclipse progressed.

This diagram shows an approximation of the Sun’s position and size as viewed by an observer at the center of the lunar disk during Friday’s penumbral eclipse. More sunlight shines across the Moon early in the eclipse, making the penumbral shadow very pale, but by maximum (right), half the sun is covered and the Moon appears darker and duskier as seen from Earth. During a total lunar eclipse, the sun is hidden completely. Credit: Bob King with Earth image by NASA

As the Moon’s leading edge approached the penumbra-umbra border, the Sun would narrow to a glaring sliver along Earth’s limb for our lucky lunar observer. Back on Earth, we’d notice that the part of the Moon closest to the umbra looked strangely gray and dusky, but the entire lunar disk would still be plainly visible. That’s what we’ll see during Friday’s eclipse. The Moon will slide right up to the umbra and then roll by, never dipping its toes in its dark waters.

During a partial eclipse, the Moon keeps going into the umbra, where the Sun is completely blocked from view save for dash of red light refracted by the Earth’s atmosphere into what would otherwise be an inky black shadow. This eclipse, the Moon only flirts with the umbra.

The moon’s orbit is tilted 5.1 degrees in relation to Earth’s orbit, so most Full Moons, it passes above or below the shadow and no eclipse occurs. Credit: Bob King

Because the moon’s orbit is tilted about 5° from the plane of Earth’s orbit, it rarely lines up for a perfect bullseye total eclipse: Sun – Earth – Moon in a straight line in that order. Instead, the moon typically passes a little above or below (north or south) of the small, circle-shaped shadow cast by our planet, and no eclipse occurs. Or it clips the outer edge of the shadow and we see — you guessed it — a penumbral eclipse.

Earth’s shadow varies in size depending where you are in it. Standing on the ground during twilight, it can grow to cover the entire sky, but at the moon’s distance of 239,000 miles, the combined penumbra and umbra span just 2.5° of sky or about the width of your thumb held at arm’s length.

The moon passes through Earth’s outer shadow, the penumbra, on Feb. 10-11. In the umbra, the sun is blocked from view, but the outer shadow isn’t as dark because varying amounts of sunlight filter in to dilute the darkness. Times are Central Standard. Credit: F. Espenak, NASA’s GFSC with additions by the author

Because the Moon travels right up to the umbra during Friday’s eclipse, it will be well worth watching.The lower left  or eastern half of the moon will appear obviously gray and blunted especially around maximum eclipse as it rises in the eastern sky that Friday evening over North and South America. I should mention here that the event is also visible from Europe, Africa, S. America and much of Asia.

This map shows where the eclipse will be visible. Most of the U.S. will see at least part of the event. Credit: F. Espenak, NASA’s GFSC

For the U.S., the eastern half of the country gets the best views. Here are CST and UT times for the different stages. To convert from CST, add an hour for Eastern, subtract one hour for Mountain and two hours for Pacific times. UT stands for Universal Time, which is essentially the same as Greenwich or “London” Time except when Daylight Saving Time is in effect:

This is a simulated view of the Full Snow Moon at maximum eclipse Friday evening low in the eastern sky alongside the familiar asterism known as the Sickle of Leo. Created with Stellarium

Eclipse begins: 4:34 p.m. (22:34 p.m. UT)
Maximum eclipse (moon deepest in shadow): 6:44 p.m. (00:43 UT Feb. 11)
Eclipse ends: 8:53 p.m. (2:53 UT Feb. 11)

You can see that the eclipse plays out over more than 4 hours, though I don’t expect most of us will either be able or would want to devote that much time. Instead, give it an hour or so when the Moon is maximally in shadow from 6 to 7:30 p.m. CST; 7-8:30 EST; 5-6:30 p.m. MST and around moonrise Pacific time.

This should be a fine and obvious eclipse because around the time of maximum, the darkest part of the penumbra shades the dark, mare-rich northern hemisphere of the Moon. Dark plus dark equals extra dark! Good luck and clear skies!

101 Astronomical Events for 2017: A Teaser

It’s that time of year again… time to look ahead at the top 101 astronomical events for the coming year.

And this year ’round, we finally took the plunge. After years of considering it, we took the next logical step in 2017 and expanded our yearly 101 Astronomical Events for the coming year into a full-fledged guide book, soon to be offered here for free download on Universe Today in the coming weeks. Hard to believe, we’ve been doing this look ahead in one form or another now since 2009.

This “blog post that takes six months to write” will be expanded into a full-fledged book. But the core idea is the same: the year in astronomy, distilled down into the very 101 best events worldwide. You will find the best occultations, bright comets, eclipses and much more. Each event will be interspersed with not only the ‘whens’ and ‘wheres,’ but fun facts, astronomical history, and heck, even a dash of astronomical poetry here and there.

It was our goal to take this beyond the realm of a simple almanac or Top 10 listicle, to something unique and special. Think of it as a cross between two classics we loved as a kid, Burnham’s Celestial Handbook and Guy Ottewell’s Astronomical Calendar, done up in as guide to the coming year in chronological format. Both references still reside on our desk, even in this age of digitization.

And we’ve incorporated reader feedback from over the years to make this forthcoming guide something special. Events will be laid out in chronological order, along with a quick-list for reference at the end. Each event is listed as a one- or two-page standalone entry, ready to be individually printed off as needed. We will also include 10 feature stories and true tales of astronomy. Some of these were  culled from the Universe Today archives, while others are new astronomical tales written just for the guide.

Great American Eclipse
Don’t miss 2017’s only total solar eclipse, crossing the United States! Image credit: Michael Zeiler/The Great American Eclipse.

The Best of the Best

Here’s a preview of some of the highlights for 2017:

-Solar cycle #24 begins to ebb in 2017. Are we heading towards yet another profound solar minimum?

-Brilliant Venus reaches greatest elongation in January and rules the dusk sky.

-45P/Honda-Mrkos-Pajdusakova passes 0.08 AU from Earth on February 11th, its closest passage for the remainder of the century.

-An annular solar eclipse spanning Africa and South America occurs on February 26th.

A sample occultation map from the book. Image credit: Occult 4.1.2.
A sample occultation map from the book. Image credit: Occult 4.1.2.

-A fine occultation of Aldebaran by the Moon on March 5th for North America… plus more occultations of the star worldwide during each lunation.

-A total solar eclipse spanning the contiguous United States on August 21st.

-A complex grouping of Mercury, Venus, Mars and the Moon in mid-September.

-Saturn’s rings at their widest for the decade.

Getting wider... the changing the of Saturn's rings. Image credit and copyright: Andrew Symes (@FailedProtostar).
Getting wider… the changing face of Saturn’s rings. Image credit and copyright: Andrew Symes (@FailedProtostar).

-A fine occultation of Regulus for North America on October 15th, with  occultations of the star by the Moon during every lunation for 2017.

-Asteroid 335 Roberta occults a +3rd magnitude star for northern Australia…

And that’s just for starters. Entries also cover greatest elongations for the inner planets and oppositions for the outer worlds, the very best asteroid occultations of bright stars, along with a brief look ahead at 2018.

Get ready for another great year of skywatching!

And as another teaser, here’s a link to a Google Calendar download of said events, complied by Chris Becke (@BeckePhysics). Thanks Chris!

Watch Asteroid 2016 VA Pass Through Earth’s Shadow

Holy low-flying space rocks, Batman.

Newly discovered asteroid 2016 VA snuck up on us last night, and crossed through the Earth’s shadow to boot.

Discovered just yesterday by the Mount Lemmon Sky Survey based outside of Tucson Arizona, 2016 VA passed just 58,600 miles (93,700 kilometers) from the surface of the Earth this morning at 00:42 Universal Time (UT). That’s a little over 20% of the distance from the Earth to the Moon, and just over twice the distance to the ring of geosynchronous and geostationary satellites around the Earth.

This sort of close pass of a newly discovered asteroid happens a few times a year. What made 2016 VA’s passage unusual, however, was its transit through the Earth’s shadow. The discovery was announced yesterday by the Minor Planet Center, and astronomer Gianluca Masi soon realized that the Virtual Telescope Project had a unique opportunity to capture the asteroid on closest approach.

The passage of asteroid 2016 VA. Image credit: The Virtual Telescope Project.
Asteroid 2016 VA. Image credit: The Virtual Telescope Project.

Gianluca Masi explained how the difficult capture was done:

“The image is a 60-second exposure, remotely taken with “Elena” (a PlaneWave 17” +Paramount ME+SBIG STL-6303E robotic unit) available at the Virtual Telescope project. The robotic mount tracked the extremely fast apparent motion of the asteroid, so stars are trailing. The asteroid is perfectly tracked; it is the sharp dot in the center, marked with two white segments. At imaging time, asteroid 2016 VA was at about 200,000 kilometers from us and approaching.”

Catching a fast-moving asteroid such as 2016 VA on closest approach isn’t easy. First off, there’s an amount of uncertainty surrounding the orbit of a newly discovered object until more observations can be made. 2016 VA passed close enough to the Earth that our planet’s gravity substantially altered the tiny asteroid’s future orbit. Also, a house-sized Earth-crosser like 2016 VA is really truckin’ across the sky on closest approach: 2016 VA was moving at 1500” a minute through Earth’s shadow – that’s 25” a second, fast enough to cross the apparent diameter of a Full Moon in just 72 seconds.

Masi also notes:

“During its flyby, asteroid 2016 VA was also eclipsed by the Earth. We covered the spectacular event, clearly capturing the penumbral effects. The movie is an amazing document showing the eclipse. Each frame comes from a 5-second integration.”

Watch as 2016 VA winks out as it hits Earth's shadow... Image credit: The Virtual Telescope Project.
Watch as 2016 VA winks out as it hits Earth’s shadow… Image credit: The Virtual Telescope Project.

At an estimated 16 to 19 meters in size, 2016 VA shined at 13th magnitude as it crossed the southern hemisphere constellation of Sculptor on closest approach. It crossed through the Earth’s shadow for 11 minutes from 23:23 to 23:34 UT last night, just over an hour before closest approach. You can see the dimming effect of the Earth’s outer penumbral shadow in the video,  just before the asteroid strikes the inner dark umbra and emerges back into eternal sunshine once again. Sitting on 2016 VA, and observer would have seen a total solar eclipse, as the bulk of the Earth passed between the asteroid and the Sun in an event not witnessed by the tiny world for thousands of years.

Such transits of asteroid through the Earth’s shadow have been observed before: 2012 XE54 crossed through the Earth’s shadow a few years back, and 2008 TC3 crossed through the Earth’s shadow before striking the Nubian desert in the early morning hours of October 7th, 2008.

Satellites in geostationary orbit also pull a similar vanishing act right around either equinox as well.

The orbit of 2016 VA. Iimage credit: NASA/JPL.
The orbit of 2016 VA. Image credit: NASA/JPL.

2016 VA is also a similar size to another famous space rock: the 20 metre asteroid that exploded over the city of Chelyabinsk the day after Valentine’s Day in 2013. 2016 VA gave us a miss, and won’t make another pass as close to the Earth again for this century.

To our knowledge, such a video capture of an asteroid crossing through Earth’s shadow is a first, or at least the first that we’ve seen circulated on ye ole Web.

The light curve of 2016 as it passed through the Earth's shadow. Image credit: Peter Birtwhistle, Great Shefford Observatory.
The light curve of 2016 as it passed through the Earth’s shadow. Image credit: Peter Birtwhistle, Great Shefford Observatory.

Congrats to the good folks at the Virtual Telescope Project for swinging into action so quickly, and providing us with an amazing view!

-Catch the closest Full Moon of the year (and for many years to come!) on November 14th live courtesy of the Virtual Telescope Project.

The Lowdown on September’s Harvest Moon

The Full Moon of August 18, 2016 - the “Sturgeon Moon” - rising amid cloud over a wheatfield. This is a 5-exposure stack blended with luminosity masks, and shot with the Canon 60Da and 135mm telephoto.
The Full Moon of August 18, 2016 rises amid cloud over a wheat field. Friday night will see the rising of the annual Harvest Moon. Credit: Alan Dyer

It’s that wonderful time of year again when the Harvest Moon teeters on the horizon at sunset. You can watch the big orange globe rise on Friday (Sept. 16) from your home or favorite open vista just as soon as the Sun goes down. Despite being one of the most common sky events, a Full Moon rise still touches our hearts and minds every time. No matter how long I live, there will never be enough of them.

Friday night's Harvest Moon rises around sunset in the faint constellation Pisces the fish. Two fists above and left of the Moon, look for the four stars that outline the massive asterism of Pegasus the flying horse. Stellarium
Friday night’s Harvest Moon rises around sunset in the faint constellation Pisces the fish. Watch for it to come up almost due east around the time of sunset. Once the sky gets dark, look two fists above and left of the Moon for the four stars that outline the spacious asterism of Pegasus the flying horse. Stellarium

To see a moonrise, the most important information you need is the time the moon pops up for your city, which you’ll find by using this Moonrise and Moonset calculator. Once you know when our neighborly night light rises, pre-arrange a spot you can walk or drive to 10-15 minutes beforehand. The waiting is fun. Who will see it first? I’ll often expect to see the Moon at a certain point along the horizon then be surprised it’s over there.

A photographer finds just the right spot in Duluth along Lake Superior to photograph the Full Moon rise. The flattened shape of the Moon is caused by the layer of denser air closer to the horizon refracting or bending the bottom half of the Moon more strongly than the thinner air n
A photographer finds just the right spot in Duluth along Lake Superior to photograph a rising Full Moon. The flattened shape of the Moon is caused by the layer of denser air closer to the horizon refracting or bending the bottom half of the Moon more strongly than the thinner air along the top limb. In effect, refraction “lifts” the bottom half of the Moon upward into the top to give it a squashed appearance. Once the Moon rises high enough so we see it through much thinner (less dense) air, refraction becomes negligible and the Moon assumes its more familiar circular shape.  Credit: Bob King

Depending on how low to the horizon you can see, it’s possible, especially over water, to catch the first glimpse of lunar limb breaching the horizon. This still can be a tricky feat because the Moon is pale, and when it rises, shows little contrast against the still-bright sky. Since the Moon moves about one outstretched fist to the east (left in the northern hemisphere) each night, if you wait until one night after full phase, the Moon will rise in a much darker sky and appear in more dramatic contrast against the sky background.

As the Moon rises, we peer through hundreds of miles of the lower atmosphere, where the air is densest and dustiest. Aerosols scatter much of the blues and greens in moonlight away, leaving orange and red. Turbulence and varying air densities along the line of sight can create all manner of distortions of the lunar disk. This photo sequence showing an extraordinary moonset was taken from the shores of Garrison Lake in Port Orford, Oregon. The camera was facing west; looking across the lake, beyond the narrow foredune and out toward the Pacific Ocean. A very clear atmosphere enabled me to watch the Moon set all the way down to the horizon. The distortion that occurred as it descended was quite remarkable -- the Moon's shape was changing as fast as I could snap a picture.  Credit: Randy Scholten
This photo sequence showing an extraordinary moonset taken from the shores of Garrison Lake in Port Orford, Oregon. “The distortion that occurred as it descended was quite remarkable — the Moon’s shape was changing as fast as I could snap a picture,” said photographer Randy Scholten. As the Moon rises, we peer through hundreds of miles of the lower atmosphere, where the air is densest and dustiest. Aerosols scatter much of the blues and greens in moonlight away, leaving orange and red. Turbulence and varying air densities along the line of sight can create all manner of distortions of the lunar disk. Credit: Randy Scholten

Look closely at the rising Moon with both naked eye and binoculars and you might just see a bit of atmospheric sorcery at work. Refraction, illustrated the icy moonrise image above, is the big one. It creates the squashed Moon shape. But more subtle things are happening that depend on how turbulent or calm the air is along your line of sight to our satellite.

Clouds add their own beauty and mystery to the rising Moon. Credit: Bob King
Clouds add their own beauty and mystery to the rising Moon. Credit: Bob King

Rippling waves “sizzling” around the lunar circumference can be striking in binoculars though the effect is quite subtle with the naked eye. Much easier to see without any optical aid are the weird shapes the Moon can assume depending upon the state of the atmosphere. It can looked stretched out like a hot air balloon, choppy with a step-like outline around its bottom or top, square, split into two moons or even resemble a “mushroom cloud”.

If you make a point to watch moonrises regularly, you’ll become acquainted as much with Earth’s atmosphere as with the alien beauty of our sole satellite.

This Full Moon is special in at least two ways. First, it will undergo a penumbral eclipse for skywatchers across eastern Europe, Africa, Asia and Australia. Observers there should watch a dusky gray shading over the upper or northern half of the Moon around the time of maximum eclipse. The link will take you to Dave Dickinson’s excellent article that appeared earlier here at Universe Today.

The angle of the moon’s path to the horizon makes all the difference in moonrise times. At full phase in spring, the path tilts steeply southward, delaying successive moonrises by over an hour. In September, the moon’s path is nearly parallel to the horizon with successive moonrises just 20+ minutes apart. Times are shown for the Duluth, Minn. region. Illustration: Bob King
The angle of the moon’s path to the horizon makes all the difference in moonrise times. At full phase in spring, the path tilts steeply southward, delaying successive moonrises by over an hour. In September, the moon’s path is nearly parallel to the horizon with successive moonrises just 20+ minutes apart. Times shown are for illustration only  — so you can see the dramatic different in rise times — and don’t refer necessarily to Friday night’s moonrise. Illustration: Bob King

In the northern hemisphere, September’s Full Moon is named the Harvest Moon, defined as the Full Moon closest to the autumnal equinox, which occurs at 9:21 a.m. CDT (14:21 UT) on the 22nd. Normally, the Moon rises on average about 50 minutes later each night as it moves eastward along its orbit. But at Harvest Moon, successive moonrises are separated by a half-hour or less as viewed from mid-northern latitudes. The short gap of time between between bright risings gave farmers in the days before electricity extra light to harvest their crops, hence the name.

Use your imagination and you can see any of several figures in the Full Moon composed of contrasting maria and highlands.
Use your imagination and you can see any of several figures in the Full Moon composed of contrasting maria and highlands.

Why the faster-than-usual moonrises? Every September, the Full Moon’s nightly travels occur at a shallow angle to the horizon; as the moon scoots eastward, it’s also moving northward this time of year as shown in the illustration above. The northern and eastward motions combine to make the Moon’s path nearly level to the horizon. For several nights in a row, it only takes a half-hour for the Earth’s rotation to carry the Moon up from below the horizon. In spring, the angle is steep because the Moon is then moving quickly southward along or near the ecliptic, the path it takes around the sky.  Rising times can exceed an hour.

As you gaze at the Moon over the next several nights, take in the contrast between its ancient crust, called the lunar highlands, and the darker seas (also known as maria, pronounced MAH-ree-uh). The crust appears white because it’s rich in calcium and aluminum, while the maria are slightly more recent basaltic lava flows rich in iron, which lends them a darker tone. Thanks to these two different types of terrain it’s easy to picture a male or female face or rabbit or anything your imagination desires.

Happy moongazing!

Our Guide to This Week’s ‘Ring of Fire’ Annular Eclipse

Ring of Fire

In Africa this week? The final solar eclipse of 2016 graces the continent on Thursday, September 1st. This eclipse is annular only, as the diminutive Moon fails to fully cover the disk of the Sun.

The 99.7 kilometer wide path crosses the African countries of Gabon, Republic of the Congo, Democratic Republic of the Congo, Tanzania, Mozambique and Madagascar. The antumbra (the ‘ring of fire path of the shadow annulus as viewed from Earth) touches down in the southern Atlantic at 7:20 Universal Time (UT) on September 1st, before racing across Africa and departing our fair planet over the Indian Ocean over four hours later at 10:55 UT. Partial phases for the eclipse will be visible across the African continent as far north as southern Morocco, Egypt and the southwestern portion of the Arabian peninsula.

Path. Credit: Xavier Jubier.
The path of this week’s eclipse across Africa. Credit: Xavier Jubier.

Tales of the Saros

This eclipse is member 39 of 71 solar eclipses for saros 135, which runs from July 5th, 1331 to August 17th, 2593. This series finally produces its first total solar eclipse on March 29, 2359.

A daguerreotype of an annular eclipse from 1854, part of the same saros 154 cycle. Public domain image.
A daguerreotype of an annular eclipse from 1854, part of the same saros 154 cycle. Public domain image.

Annular eclipses occur when the Moon is too distant to cover the Sun as seen from the Earth. The Moon reaches apogee, or its most distant point from the Earth on September 6th, just five days after New and the September 1st eclipse.

How common (or rare) are solar eclipses, annular or total? It’s worth noting that as the 2017 total solar eclipse crossing the contiguous United States approaches, creationist websites are again promoting the idea that the supposed ‘perfection’ of solar eclipses is evidence for intelligent design. If solar eclipses are an example of a higher plan to the cosmos, they’re not a very good one… in fact, in our current epoch, partial eclipses, to include annulars, are much more prevalent. If, for example, the Moon’s orbit was aligned with the ecliptic, we’d see two eclipses – one lunar and and one solar – every month, a much rarer circumstance… a creator could have really used that to really get our attention. And Earth isn’t alone in hosting total solar eclipses: in our own solar system, you can make a brief visit to Jupiter’s large moons and also witness total solar eclipse perfection.

Unlike a total solar eclipse, proper eye protection must be worn throughout all stages of an annular eclipse. We witnessed annularity from the shores of Lake Erie back in 1994, and can attest that a few percent of the Sun is still surprisingly bright. The tireless purveyors of astronomy over at Astronomers Without Borders are working to distribute eclipse glasses to schools and students along the eclipse path.

An animation of Thursday's eclipse. Credit: NASA/GSFC.
An animation of Thursday’s eclipse. Credit: NASA/GSFC.

Are you in the path of this week’s annular eclipse? Let us know, and send those images in to Universe Today on Flickr.

We’ll most likely see more than a few images of the eclipse from space as well. And no, we’re not talking about the cheesy composite that now makes its rounds during every eclipse… solar observing satellites to include the European Space Agency’s Proba-2 and the joint JAXA/NASA Hinode mission typically capture several successive eclipses as they observe the Sun from their vantage point in low Earth orbit.

At this stage, we only know of one webcast set to broadcast the eclipse live: the venerable Slooh website.

Let us know if you’re planning on setting up an ad hoc live webcast of the eclipse, even from outside the path of annularity.

And of course, the big question on every eclipse-chaser’s mind is: when’s the next one? Well, we’ve got a subtle penumbral eclipse on September 16th, 2016, and then the next solar eclipse is another annular favoring Argentina, Chile and the west coast of southern Africa on February 26th, 2017.

Don’t miss this week’s annular solar eclipse, either live online or in person, for a chance to marvel at a celestial phenomenon we all share in time and space.

-Eclipse… science fiction? Yup… read Dave Dickinson’s eclipse-fueled tales Peak SeasonExeligmos, Shadowfall and The Syzygy Gambit.

Citizen Scientists Help Crack 300 Year Old Mystery Of Eclipse Wind

Being able to witness a solar eclipse is certainly a distinct experience. Even though the spectacle is mostly visual, there can be other effects as well. The air can cool, and observers may notice a decrease in wind speed or a change in wind direction. There might even be an eerie silence.

Experiences like this have been noted for centuries, and famed astronomer Edmund Halley wrote of the ‘Chill and Damp which attended the Darkness’ during an eclipse in 1715, which he noted caused ‘some sense of Horror’ among those who were witnessing the event.

While most people would describe an eclipse as ‘awe-inspiring’ (and not horrifying at all) the atmospheric changes noted by observers over the years has been called the “eclipse wind.” And now, based on the observations of over 4,500 citizen scientists in the UK during the partial eclipse on March 20, 2015, this effect is not just a figment of anyone’s imagination; it is a real phenomenon.

Partial phases of the solar eclipse on March 20, 2015 as seen from the United Kingdom. Credit and copyright: Sarah and Simon Fisher.
Partial phases of the solar eclipse today as seen from the United Kingdom. Credit and copyright: Sarah and Simon Fisher.

The National Eclipse Weather Experiment (NEWEx) was a UK-wide citizen science project for collecting atmospheric data during that eclipse. Members of the public – including about 200 schools – recorded weather changes such as air temperature, wind speed, wind direction and cloud cover every five minutes during the eclipse. That data, submitted online, was compared with official data from the UK’s Met office observations, the United Kingdom’s national weather service.

“The NEWEx was, as far as we know, a world first, in measuring and analyzing eclipse changes in the weather on a national scale, in close to real time, through engagement of a network of citizen scientists,” wrote researchers Luke Barnard, Giles Harrison, Suzanne Gray and Antonio Portas from the University of Reading, in one of a series of new papers about eclipse meteorology published this week.

The data revealed that not only did the atmosphere cool during the eclipse – which is not surprising since solar radiation is being blocked by the Moon – but the winds and cloud cover also decreased. The cumulative effect is real, not just anecdotal, the team said.

The Data

NEWEx collected 15,606 meteorological observations from 309 locations within the UK and from those observations the science team was able to derive estimates of the near-surface air temperature, cloudiness and near-surface wind speed fields across many UK sites. The data submitted by citizen scientists were combined with Met Office surface weather stations and a network of roadside weather sensors that monitor highway conditions. The combination of data helped unravel the centuries-old mystery of the eclipse wind.

Geographical distribution of participants in the NEWEx citizen science project during the March 20, 2015 solar eclipse in the UK, with designations between schools (yellow squares) and non-schools (pink dots). Credit: Antonio M. Portas, Luke Barnard, Chris Scott, R. Giles Harrison.
Geographical distribution of participants in the NEWEx citizen science project during the March 20, 2015 solar eclipse in the UK, with designations between schools (yellow squares) and non-schools (pink dots). Credit: Antonio M. Portas, Luke Barnard, Chris Scott, R. Giles Harrison.
From analysis of the data, they found that the wind change is caused by variations to the “boundary layer” – the area of air that usually separates high-level winds from those at the ground.

“There have been lots of theories about the eclipse wind over the years, but we think this is the most compelling explanation yet,” said Harrison in a press release from the University of Reading in the UK. “As the sun disappears behind the moon the ground suddenly cools, just like at sunset. This means warm air stops rising from the ground, causing a drop in wind speed and a shift in its direction, as the slowing of the air by the Earth’s surface changes.”

The measurements from citizen scientists clearly showed temperature drops and a decrease in clouds. The team did note that because of the low velocity of winds and some areas where cloud cover change was small, it was difficult for the participants to make some of the measurements. But the high level of participation across the UK provided enough data for the team to make their conclusions.

“Halley also relied on combining eclipse observations from amateur investigators across Britain. We have continued his approach,” Harrison said.

A total of 16 new papers and reports were published this week in a special ‘eclipse meteorology’ issue of the world’s oldest scientific journal, Philosophical Transactions of the Royal Society A. The special issue is published 301 years after Halley’s report of the eclipse in London in 1715 – and in exactly the same journal.

The team wrote that they hope a similar citizen science effort might take place in August 2017, when a total solar eclipse will be visible from North America, providing another opportunity to study eclipse-induced meteorology changes.
“NEWEx serves as a useful example of the strengths and challenges of using a citizen science approach to study eclipse-induced meteorological changes, and could provide a template for a similar study for the August 2017 eclipse,” the team said.

Sources: Paper: The National Eclipse Weather Experiment: an assessment of citizen scientist weather observations, Philosophical Transactions of the Royal Society A, University of Reading.

One Year to the 2017 Total Solar Eclipse

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One. More. Year. Quick; where will you be this time next year on August 21st, 2017? We’re now just one year out this weekend from a fine total solar eclipse gracing the United States from coast to coast. If you think one year out is too early to start planning, well, umbraphiles (those who chase the shadow of the Moon worldwide) have been planning to catch this one now for over a decade.

The shadow of the March 9th, 2016 solar eclipse as seen from the Himawari-8 Earth-observing satellite. image credit: JAXA/JMA/Himawari/CIMSS
The shadow of the March 9th, 2016 solar eclipse (the dark spot on the right) as seen from the Himawari-8 Earth-observing satellite. Image credit: JAXA/JMA/Himawari/CIMSS.

Get set for the Great American Eclipse. The last time a total solar eclipse made landfall over a U.S. state was Hawaii on July 11th, 1991, and the path of totality hasn’t touched down over the contiguous ‘Lower 48’ United States since February 26th, 1979. And you have to go all the way back over nearly a century to June 8th, 1918 to find an eclipse that exclusively crossed the United States from the Pacific to the Atlantic Coast.

The path of the 2017 total solar eclipse across the U.S. image credit and copyright: Michael Zeiler/The GreatAmercianEclipse
The path of the 2017 total solar eclipse across the U.S. Image credit and copyright: Michael Zeiler/The GreatAmercianEclipse

Totality for the August 21st, 2017 eclipse crosses over many major cities, including Columbia South Carolina, Nashville, St. Louis and Salem, Oregon. The inner shadow of the Moon touches on 15 states as it races across the U.S. in just over an hour and a half. The length of totality is about 2 minutes in duration as the shadow makes landfall near Lincoln City, Oregon, reaches a maximum duration of 2 minutes, 42 seconds very near Carbondale, Illinois, and shrinks back down to 2 minutes and 35 seconds as the shadow heads back out to sea over Charleston, South Carolina.

The eclipse will be a late morning affair in the northwest, occurring at high noon over western Nebraska, and early afternoon to the east. ‘Getting your ass to totality,’ is a must. “But I’ve seen a partial solar eclipse,” is a common refrain, “aren’t they all the same?”

An animation of the 2017 eclipse.
An animation of the 2017 eclipse.

Nope. We witnessed the May 10th, 1994 annular eclipse from the shores of Lake Erie, and can tell you that even less than 1% of the Sun’s intensity is still pretty bright, a steely blue luminosity equivalent to a cloudy day.

We crisscrossed the United States along the eclipse path back in 2014, chronicling preparations in towns such as Columbia and Hopkinsville, Kentucky. Last minute accommodation is already tough to come by, even one year out. Cabins in the Land Between the Lakes region near Paducah, Kentucky, for example, were booked full as soon as the August 21st date became available. Think Mardi Gras and DragonCon, rolled into one. Hopkinsville also has an annual Roswell-style UFO-fest on the same date, celebrating the 1955 Kelly-Hopkinsville UFO incident.

Will it be ‘umbraphiles versus aliens?’

Out west, enticing locales include the Grand Teton National Park and Jackson Hole, Wyoming and the northern edge of the Craters of the Moon National Monument site in Idaho. It’s also worth noting that the western United States is a better bet cloud cover-wise, as afternoon summer thundershowers tend to be the norm for the southeast during late August.

Millions live within an easy day drive of the eclipse path, and it happens during prime camping season, to boot. The annual Sturgess motorcycle rally held near Rapid City, South Dakota is just one week prior to totality, and bikers returning from the pilgrimage southward could easily stop to greet the Earth’s shadow on the road home.

2017 Eclipse Panorama from Michael Zeiler on Vimeo.

There’s been talk that Cosmoquest may mount an eclipse expedition based out of Nashville, Tennessee (more to come on that).

Maintaining mobility is the best bet. Our master plan is to return to the States a week or so prior, rent a camper van from Vegas, and head northward. Like millions of Americans, this will be our first total solar eclipse, and the event promises to spark a whole new generation of umbraphiles. And stick around just seven more years, and totality will again cross the United States on August 8th, 2024 from the southwest to the northeast. The Illinois, Missouri and Kentucky tri-state region sees this eclipse as well. This one is special for us, as it crosses over our hometown of Presque Isle, Maine. I remember looking up the next total solar eclipse over northern Maine as a kid, way back when, and figuring out just how old I would be. The top of Mount Katahdin and selected sites along the Maine Solar System model would all be choice locales to view this one. Check out this great old vid of the aforementioned 1979 eclipse over the U.S.:

We also plan on taking the veteran eclipse-chaser’s mantra of ‘experience your first eclipse; but photograph your second one.’ to heart. Lots of fascinating projects are afoot leading up to the 2017 total solar eclipse, including The Eclipse MegaMovie Project to produce a complete video documentary of the eclipse path, plans by a student group to fly and observe the eclipse from balloons during totality, proposals to replicate famous eclipse experiments and more. It’s also worth noting that the bright star Regulus will sit just one degree from the Sun during totality… perhaps someone will manage to measure its deflection via General Relativity in a manner similar to Sir Arthur Eddington’s famous 1919 observation?

Unlike the paths of most eclipses, which seem to have an affinity for wind-swept tundra or remote swaths of desert, this one is sure to draw in the ‘astronomy-curious’ and may just be the most witnessed total solar eclipse in history.

Here’s some eclipse tales and facts to ponder leading up to totality. If you caught the August 11th, 1999 eclipse across Europe, then you saw the last eclipse in the same saros series 145. If you caught the eclipse before that in the same series on July 31st, 1981 across northeast Asia, then you’ll complete a 54 year long triple-saros period after seeing next summer’s eclipse, known as an exeligmos. This cycle also brings the eclipse path very nearly back around to the same longitude.

Stellarium
Regulus near the  eclipsed Sun next August. Credit: Stellarium.

The Sun is about 400 times larger than the Moon in diameter, but the Moon is 400 times closer. We’ve actually heard this fact tossed out as evidence for intelligent design, though it’s just a happy celestial circumstance of our present era. In fact, annular eclipses are now slightly more common than totals in our current epoch, and will continue to become more so as the Moon slowly recedes from the Earth. Just under a billion years ago, the very first annular eclipse of the Sun as seen from the Earth occurred, and 1.4 billion years hence, the Earth will witness one last brief total eclipse.

But you won’t have to wait that long. Don’t miss the greatest show in the universe next August!

-Check out Michael Zeiler’s (@EclipseMaps) 10-foot long strip map of the entire eclipse path.

-Eclipses, both lunar and solar have played a role in history as well.

-Curious about eclipses in time and space? Read our eclipse-fueled sci-fi tales, Exeligmos, The Syzygy Gambit and Shadowfall, with more to come!

A Penumbral Lunar Eclipse Leads the Way to Easter Weekend

Chuck Manges

Ready for Easter? The first of two lunar eclipses for 2016 occurs this week, though it’s an event so subtle, you might not notice it at first glance. We’re talking about Wednesday evening’s (morning for North America) penumbral lunar eclipse. If a total solar eclipse such as the one that crossed Indonesia and the Pacific Ocean earlier this month is the ultimate astronomical experience, then a penumbral lunar eclipse is at the other end of the spectrum, a ghostly shading on the Moon that is barely noticeable. Continue reading “A Penumbral Lunar Eclipse Leads the Way to Easter Weekend”

DSCOVR Captures EPIC Views of the March 2016 Eclipse

On March 8, 2016 (March 9 local time) the Moon briefly blocked the light from the Sun in what was the only total solar eclipse of the year. The event was visible across portions of southeast Asia, Indonesia, and Micronesia, and was observed by both skywatchers on the ground in person and those watching live online around the world. While to most the view was of a silhouetted Moon slowly carving away the disk of the Sun before totality revealed a shimmering corona, the view from space looking back at Earth showed the Moon’s dark shadow passing over islands, clouds, and sea.

Continue reading “DSCOVR Captures EPIC Views of the March 2016 Eclipse”

Standing in the Shadow: Amazing Images of Today’s Total Solar Eclipse

The Moon’s shadow kissed the Earth earlier today, providing a fine show from southeast Asia, to the southern shores of Alaska. We wrote about the only total solar eclipse for 2016 yesterday. This is it, the last total solar eclipse prior to the return of totality for the contiguous United States on August 21st, 2017.

Cloud cover over the region was a toss up, with clear skies for some, and cloudy skies for others. Those towards the western end of the track where the eclipsed rising Sun sat low on the horizon seemed to have fared worst.

Image credit:
Clouds thwarted a Malaysian team that had journeyed to Indonesia to view the eclipse (including Sharin Ahmad @shahgazer), though they were at the ready. Image credit and copyright: Sharin Ahmad.

Update: Sometimes, the camera sees what the eye misses. The Malaysian team did indeed manage to nab a fine display of Bailey’s Beads in the moments leading up to totality through a thin gap in the clouds:

Sunlight, interupted. A welcome photobomb courtesy of the Earth's Moon. Image credit and copyright: Shahrin Ahmad. (@shahgazer)
Sunlight, interupted. A welcome photobomb courtesy of the Earth’s Moon. Image credit and copyright: Shahrin Ahmad. (@shahgazer)

Skies dawned clear to the east over the Indonesian islands on the morning of the eclipse, and the joint NASA/Exploratorium webcast from the remote atoll of Woleai in Micronesia was a success.

Image credit
A ‘helipad solar observatory’ readied for the eclipse. Image credit and copyright: Patrick Poitevin.

Observing from a helipad Balikpanpan, Indonesia, veteran eclipse chaser Patrick Poitevin said: “What an eclipse! Vertically clear sky throughout the entire eclipse from our ‘private’ helipad in Balikpapan. Only slight haze now and then. Asymmetric corona, with bright and prominent snow white streamer. Venus, Mercury easily visible long before, and shadow bands post totality. Fabulous! All so pretty!!! Marked the second Saros 130 for Jo and the 3rd for me.”

Image credit
Many viewers noted a fine solar prominence on the solar limb seen during totality. Patrick Poitevin caught the prominence using a hydrogen-alpha solar telescope just moments before the onset of totality. Image credit: Patrick Poitevin.

Indeed, catching a ‘triple saros’ known as an exeligmos is a noteworthy lifetime accomplishment.

09 March 2016 - Total Solar Eclipse from Palu, Indonesia. Image credit and copyright: Justin Ng.
09 March 2016 – Total Solar Eclipse from Palu, Indonesia. Image credit and copyright: Justin Ng.

Many witnessed the eclipse via Slooh’s live webcast from the path of totality, which is now archived in its entirety on YouTube.

Totality, as witnessed by the Slooh team in Indonesia. Image credit: www.slooh.com
Totality, as witnessed by the Slooh team in Indonesia. Image credit: www.slooh.com

As of writing this, no views from space have surfaced, though we suspect this will change as the day goes on. Word is that the Alaskan Airlines flight that modified their flight plan to catch the eclipse was successful as well. Check back, as we’ll be dropping in more images as they trickle in from the field throughout the day.

The partial phases of today's eclipse as seen from Lava Lava, Hawaii. image credit and copyright: Rob Sparks (@halfastro)
The partial phases of today’s eclipse as seen from Lava Lava, Hawaii. Image credit and copyright: Rob Sparks (@halfastro)

Update: Scratch that… Japan’s Himawari-8 weather satellite did indeed nab views of the umbra of the Moon as it raced across the Pacific:

An animation of today's total solar eclipse as seen from space. Image credit: The Meteorological Satellite Center of JAMA.
An animation of today’s total solar eclipse as seen from space. Image credit: The Meteorological Satellite Center of JAMA.

Though the eclipse was almost entirely over water after the umbra departed SE Asia, regions around the path were treated to a fine partial eclipse, including residents of Hawaii:

August 21st 2017 is now the very next total solar eclipse in the queue!

Update: and the amazing images just keep on coming… here’s an amazing image and time lapse video courtesy of astrophotographer Justin Ng:

09 March 2016 - Total Solar Eclipse from Palu, Indonesia. Image credit and copyright: Justin Ng Photography.
09 March 2016 – Total Solar Eclipse from Palu, Indonesia. Image credit and copyright: Justin Ng Photography.

And timelapse:

2016 Total Solar Eclipse – Palu Indonesia from Justin Ng Photo on Vimeo.

Wow. just wow!