A Partial Solar Eclipse and the Perseids Round Out August

A partial solar eclipse rising over the Vehicle Assembly Building along the Florida Space Coast. Credit: Dave Dickinson

How about that Total Lunar Eclipse this past July 13th? It has been a busy year for astronomy for sure, with two total lunar eclipses, a comet fading out from an unexpected burst of glory, and Saturn, Jupiter and Mars reaching opposition in quick succession.

Now, watch for a rare event this weekend, with the final eclipse for 2018 coming up on Saturday, August 11th, with a partial solar eclipse spanning northern Europe and the Arctic.

Circumstances for the August 11th, 2018 partial solar eclipse. Credit: NASA/GSFC/Fred Espenak

What’s so unique about this eclipse? Well, not only is it the last one for 2018, but it’s part of three eclipses in the second eclipse season of the year. Most seasons only feature two eclipses (one lunar and one solar) but every few years or so, it is possible to have a season with three: either lunar-solar-lunar (such as occurred in 2013) or solar-lunar-solar.

This is only possible when the middle eclipse occurs very near ascending or descending node along the ecliptic. The nodes are where the path of the Moon, inclined 5.1 degrees relative to the ecliptic plane intersect it—when these nodes are occupied by an alignment of the Earth, Sun and Moon (known as a syzygy, a fine word in Scrabble to land on a triple word score, though you’ll need a blank tile for the third ‘y’) a solar or lunar eclipse occurs. For an eclipse triple play, the middle eclipse needs to happen very near a node crossing, producing a fairly long eclipse. That’s exactly what happened on July 28th, when the Moon crossed through descending node just over an hour after crossing out of the Earth’s umbral shadow after the longest lunar eclipse for the 21st century.

This also leaves the Moon close enough to the opposite ascending node two weeks post and prior to July 28th on July 13th and August 11th to just nick the Sun for a partial solar eclipse, one over the Antarctic and one over the Arctic.

The animated path for the August 11th partial solar eclipse. Credit: A.T. Sinclair/NASA/GSFC

Eclipse Circumstances

Saturday’s partial eclipse touches down over the eastern coast of Canada at sunrise. From there, it sweeps eastward over Greenland, Iceland and the North Atlantic, with the Moon’s penumbra just grazing the northern United Kingdom before crossing over Scandinavia. Then, the shadow crosses over Asia, with a photogenic partial solar eclipse wrapping up at sunset over eastern China, the Koreas and the Russian far east.

Note that this eclipse is also a relative newcomer for its particular saros 155, as it is member 6 of a series of 71 eclipses. The saros just began less than a century ago on June 17th, 1928, and won’t produce its first total solar eclipse until September 12th, 2072 AD.

As of this writing, we’ve yet to see evidence of anyone carrying the eclipse live, though we’ll note it here if any webcast(s) surface.

When is the next one? Well, the next partial solar eclipse is on January 6th 2019, and the next total solar eclipse occurs on July 2nd, 2019.

Enter the Perseids

This weekend’s eclipse at New Moon also sets us up for a fine display of the Perseid meteors for 2018. This year, the Perseids are expected to peak on the morning of August 12th and August 13th. Watch for a zenithal hourly rate of 100 meteors per hour at the peak. A dependable annual favorite, the Perseids are debris remnants of period comet 109/P Swift-Tuttle.

The live webcast for the 2018 Perseid meteor shower. Credit: The Virtual Telescope Project.

Astronomer Gianluca Masi and the Virtual Telescope Project 2.0 will host a live webcast for the 2018 Perseids on August 12th starting at 20:30 UT.

Don’t miss the astronomical action worldwide this weekend, either live or online.

A Partial Solar Eclipse Down Under

partial solar eclipse
partial solar eclipse
A partial solar eclipse as seen from New York City on November 3rd, 2013. Image credit and copyright: Valentin Lyakhovich

Eclipse season in nigh… though most of us won’t notice the start this week. The second eclipse season for 2018 commences with the arrival of New Moon and Brown Lunation number 1182 at 3:01 Universal Time on (triskaidekaphobics take note) Friday July 13th, 2018. This eclipse is a shallow partial, just skimming the southern hemisphere of the Earth between the Australian and Antarctic continents.

The Eclipse

We doubt many eclipse chasers will make the pilgrimage to Tasmania to see such a slim partial, though we know of at least one, veteran eclipse chaser Jay Pasachoff who has expressed intent on the Yahoo! Solar Eclipse Message List (SEML) message board to head southward this week.

partial eclipse
The course of the July 13th, 2018 partial solar eclipse. NASA/A.T. Sinclair/GSFC

Tasmania gets the best view, with a maximum 9.5% obscuration of Sol as seen from the capital Hobart around 3:25 UT. The upper limit of the eclipse path just skims the southern coast of Australia across the Great Australian Bight and the southern Indian Ocean, and nicks the very southern tip of the south island of New Zealand and Steward Island at 3:48 UT with a barely discernible 1% eclipse before the lunar penumbra departs the Earth. If skies are clear, the very best view just might come along the coast of Antarctica, as the 33% eclipsed Sun rolls along the northern horizon.

Antarctic view
Looking northward along the Antarctic coast on July 13th. Credit: Stellarium

Perhaps a few lone penguins will notice, if they bother to look at the Sun filtered through the murk of the atmosphere along the horizon. France does have one permanently occupied research station in Antarctica named Dumont D’urville along the coast that will see a 30% eclipsed Sun on the horizon right around 3:00-3:15 UT.

We say that this heralds the start of eclipse season, as the ascending node where the Moon’s orbit intersects the ecliptic plane is very near the current position of the Sun. In fact, node crossing occurs at 18:50 UT on July 13th, just 24 hours after New Moon. Eclipses always occur in at least pairs, and the Full Moon two weeks later is close enough to the descending node for a nearly central total lunar eclipse on July 27th (more on that in a bit). This season, however, is special, with a third eclipse ending the cycle on August 11th, 2018, this time gracing the Arctic pole of the Earth along with Scandinavia and Russia.

We’re already seeing some hype surrounding this event as a “Supermoon eclipse,” as the Moon reaches perigee 5 hours 27 minutes past maximum eclipse. Note that this also sets us up for a Minimoon total lunar eclipse two weeks later, as the Moon is near apogee on July 27th.

The Moon’s orbit is tilted 5.145 degrees relative to the plane of the ecliptic, and the nodes make one full revolution around the Earth relative to the equinoctial points once every 18.6 years in what’s known as the precession of the line of apsides.

Viewing a Partial

A partial solar eclipse means that all safety precautions must be taken throughout all phases of the eclipse. This means using approved solar filters that fit snugly over the aperture of a telescope, and solar glasses with the approved ISO 12312-2 rating for solar viewing. We built a safe binocular filter out of a set of spare eclipse safety glasses for the August 21st, 2017 total solar eclipse last year.

Eclipse Safety
Practicing eclipse safety at the Pisgah Astronomical Research Institute in North Carolina during the August 21st, 2017 Great American Eclipse. Image credit: Myscha Theriault

Unfortunately as of writing this, the disk of Sol is blank in terms of Earthward facing sunspots, and may be so on eclipse day. We’re currently headed towards a profound solar minimum and the Sun has already been spotless for more than half of 2018 thus far.

Don’t own a solar filter, safety glasses or a telescope? You can always use our tried and true method of projecting the eclipse using a spaghetti strainer.

It’s all in the gamma. This eclipse is partial only, because the dark inner shadow or umbra misses the Earth by 35.4% of the radius of the planet or about 1,400 miles. The gamma for an eclipse states how many Earth radii an eclipse deviates from central (where the Moon’s umbra is aimed straight at the center of the Earth) and Friday’s eclipse has a gamma value of 1.3541.

Tales of the Saros

Friday’s eclipse is part of an older saros series, member 69 of 71 eclipses for saros series 117. This saros started waaaaaay back on June 24th, 792 AD, and produced its last total solar eclipse on May 9th, 1910. This was also the last total solar eclipse for Tasmania until June 25th, 2131. This series only has two more eclipses to go, with its last event occurring briefly over the Antarctic on August 3rd, 2054. Perhaps, Friday’s event will be the very last one witnessed by human eyes for saros 117.

Tasmania eclipse
Mr. E. Carns Driffield’s drawing of Total Solar Eclipse of the Sun on 9 May 1910. Image credit: Joy Olney.

This also sets us up for the best of the three eclipses this season, the total lunar eclipse at the end of the month on July 27th. This eclipse will be widely visible across Africa, Europe, Asia and Australia—only the Americas miss out.

A Possible Views… “From Spaaaaaaace…”

The International Space Station also threads its way through the outer shadow of the Moon towards the end of the event Friday at ~3:50 UT. ESA’s solar observing Proba-2 spacecraft might just get a very brief view as well from its vantage point in low Earth orbit, around 3:09 UT.

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Proba-2’s brief view of the eclipse on July 13th at 3:08 UT. Credit: Starry Night.

And although most of us miss out on Friday’s eclipse, you can still try and spot the slender crescent Moon on the evening of Friday, July 13th. The U.S. East Coast is particularly well placed to try and spy the slim Moon low to the west, only 22 hours after New. After that, the Moon tours all of the naked eye planets, passing Mercury and Venus this weekend and passing Jupiter, Saturn and Mars en route to the July 27th total lunar eclipse.

Will anyone webcast the eclipse live? So far, no webcasts (not even from the venerable Slooh site) have surfaced… if anyone else is planning on featuring the July 13th partial solar eclipse, let us know!

It’s the biggest question when it comes to solar eclipses. When’s the next total? Well, just under a year from now, the next total solar eclipse crosses Chile and Argentina on July 2nd, 2019. Note that this event crosses over several major astronomical observatories at La Silla. How many newly minted eclipse chasers fresh off last year’s Great American Eclipse experience can’t wait until totality next visits the United States on April 8th , 2024 and plan to head to South America next summer?

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Partial eclipse rising over the Vehicle Assembly Building at the Kennedy Space Center on the morning of November 3rd, 2013. Image credit: Dave Dickinson.

A partial eclipse may not inspire many eclipse chasers to hop on a plane, but we can still marvel at the celestial ticks of a clockwork Universe carry on, right on schedule.

-Got the eclipse chasing bug? Read all about eclipse chasing, observing and photography in our new book, the Universe Today Guide to Viewing the Cosmos: Everything You Need to know to Become and Amateur Astronomer out on October 23rd.

Beautiful Images of the October 23, 2014, Partial Solar Eclipse

“The Sun looks like it has a bite taken out of it!” said one enthusiastic viewer of the partial solar eclipse on October 23. Although I only had my paper plate pinhole projector that I shared with a crowd of folks (you can see an image of it near the bottom of the images here), the funny-looking Sun projected onto the plate definitely looked like a cookie with bite out of it or a clipped fingernail. But thankfully, as the Moon moved in front of the Sun today, legions of astrophotographers were out to take fantastic images of the eclipse. And the gigantic sunspot named AR 2192 made a cameo appearance as well. Enjoy the gallery below!

Thanks to everyone who uploaded images to our Flickr page or shared their images on Twitter.

An artistic view of the Partial Solar Eclipse, October 23, 2014. Credit and copyright: A Nartist.
An artistic view of the Partial Solar Eclipse, October 23, 2014. Credit and copyright: A Nartist.
The setting Sun, shadowed by the Moon and spotted with intense magnetic activity on October 23, 2014. Credit and copyright: Tavi Greiner.
The setting Sun, shadowed by the Moon and spotted with intense magnetic activity on October 23, 2014. Credit and copyright: Tavi Greiner.
Solar eclipse over the Flatirons near Boulder, Colorado.  A syzygy, with the Earth and Moon simultaneously transiting the Sun. Credit and copyright: Alex Parker.
Solar eclipse over the Flatirons near Boulder, Colorado. A syzygy, with the Earth and Moon simultaneously transiting the Sun. Credit and copyright: Alex Parker.
Partial Solar Eclipse of October 23, 2014 at 280mm. Credit and copyright: Forrest Tanaka.
Partial Solar Eclipse of October 23, 2014, at 280mm. Credit and copyright: Forrest Tanaka.
The sun sets while still in eclipse as seen from Duluth, Minn. Thursday evening October 23. Credit and copyright: Bob King.
The sun sets while still in eclipse as seen from Duluth, Minn., Thursday evening October 23. Credit and copyright: Bob King.
The solar eclipse on October 23, 2014, showing the Sun dotted by sunspots and airplane contrails. Credit and copyright: Greg Hogan.
The solar eclipse on October 23, 2014, showing the Sun dotted by sunspots and airplane contrails. Credit and copyright: Greg Hogan.
A cloudy closeup of the partial solar eclipse on October 23, 2014. Credit and copyright: JCC_Starguy on Flickr.
A cloudy closeup of the partial solar eclipse on October 23, 2014. Credit and copyright: JCC_Starguy on Flickr.
The cusps of the Sun's disk are just visible above the horizon as the solar eclipse of October 23, 2014 fades out over Iowa. Credit and copyright: Alan Boyle/NBC News.
The cusps of the Sun’s disk are just visible above the horizon as the solar eclipse of October 23, 2014, fades out over Iowa. Credit and copyright: Alan Boyle/NBC News.
A partial solar eclipse is visable just before sunset Thursday, Oct. 23, 2014, in Arlington, VA. Photo Credit: (NASA/Bill Ingalls)
A partial solar eclipse is visable just before sunset Thursday, Oct. 23, 2014, in Arlington, VA. Photo Credit: (NASA/Bill Ingalls)
The partial solar eclipse as viewed through a paper plate pinhole projector. Credit, copyright and pinhole: Nancy Atkinson.
The partial solar eclipse as viewed through a paper plate pinhole projector. Credit, copyright and pinhole: Nancy Atkinson.

See more great images on Universe Today’s Flickr pool page.

How to Take Great Photographs of the October 23rd Partial Solar Eclipse and More

Get those solar viewers out… the final eclipse of 2014 occurs this Thursday on October 23rd, and most of North America has a front row seat. Though this solar eclipse will be an exclusively partial one as the Moon takes a ‘bite’ out the disk of the Sun, such an event is always fascinating to witness. And for viewers across the central U.S. and Canada, it will also provide the chance to photograph the setting crescent Sun along with foreground objects.

Michael Zieler
A map showing the eclipse prospects over the CONUS. (click to enlarge). Credit: Michael Zeiler @EclipseMaps, www.thegreatamericaneclipse.com.

The shadow or ‘antumbra’ of the Moon just misses northern limb of the Earth on October 23rd, resulting in a solar eclipse that reaches a maximum of 81% partial as seen from the high Canadian Arctic. The eclipse would be annular in any event had the Moon’s shadow touched down on Earth’s surface, as the Moon just passed apogee on October 18th. The penumbral cone of the Moon’s shadow touches down at 19:38 UT in the Bering Sea just west of the International Date Line before racing eastward across North America to depart the Earth over southern Texas at 23:52 UT.

NASA/GSFC
An animated .gif of this week’s partial solar eclipse.  Credit: NASA/GSFC/A.T. Sinclair.

The farther northwest you are, the greater the eclipse: For example, Anchorage and Seattle will see 54.8% and 54.5% of the Sun obscured by the Moon, while Mexico City and Phoenix, Arizona will see 4.8% and 33% of the Sun’s disk obscured.

A key region will be the zone of longitude running a few hundred miles east and to the west of Ontario, the Great Lakes and the Mississippi River, which will see the Sun setting during greatest eclipse.

Stellarium
Simulated views of the October 23rd partial solar eclipse from around North America. Created using Stellarium.

Successful sunset viewing of the eclipse will call for a clear, uncluttered western horizon. As of 48+ hours out, the current weather prospects call for clear skies across most of the U.S. on Thursday, with the exception of the U.S. northwest… but you only need a gap in the clouds to observe an eclipse!

NOAA
Predicted cloud cover for the CONUS hours prior to the start of the Oct 23 partial solar eclipse. Credit: NWS/NOAA.

It’s also worth noting that massive sunspot region AR 2192 is currently turned Earthward and will make for a very active and photogenic Sun during Thursday’s eclipse.

SDO/HMI
Sunspot activity leading up to this week’s eclipse. Credit: NASA/SDO/HMI

Proper safety precautions must be taken while observing the Sun through all stages of a partial solar eclipse. Don’t end up like 19th century psychologist Gustav Fechner, who blinded himself staring at the Sun! With the recent interest in the event, we’ve been fielding lots of questions on eclipse imaging, which presents safety challenges of its own.

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An homemade solar optical filter using Baader film. Credit: Eric Teske/Stellar Neophyte.

Imaging the Sun with a solar filter is pretty straightforward. Glass solar filters for telescopes fitting over the full aperture of the instrument can be had from Orion for about $100 USD, and we’ve made inexpensive filter masks out of Baader AstroSolar Safety Film for everything from binoculars to DLSR cameras to telescopes. Make sure these fit snugly in place, and inspect them for pin holes prior to use. Also, be sure to cover or remove any finderscopes as well. And throw away those old screw-on eyepiece filters sold by some department store scope manufacturers in the 60s and 70s, as they can overheat and crack!

Catching the eclipsed Sun with a silhouetted foreground requires more practice. We’ve had great luck using a DSLR and a neutral density filter to take the f-stop and glare down while preserving the foreground view. Remember, though, an ND filter is for photographic use only… never stare at the Sun through one! Likewise, you’ll need to physically block off your camera’s viewfinder to resist the same temptation of looking while aiming. Shooting several quick frames at 1/1000th of a second or faster will help get the ISO/f-stop settings for the local illumination just right. Even 1% sunlight is surprisingly bright, as we noticed observing the May 10th 1994 annular eclipse from the shores of Lake Erie.

You’ll also need a lens with a focal length of 200mm or better to have the Sun appear larger than a dot in your images. Several key landmarks, such as the Saint Louis Arch and the Sears Tower in Chicago lie along the key sunset zone Thursday and  would make great potential foreground shots… our top pick would be the 1978 World’s Fair Sunsphere Tower in Knoxville, Tennessee for a photo with a true visual double entendre. Scout out the geometry of such a shot the evening beforehand, and remember that you’ll need a good amount of distance (half a mile or more) for a building or foreground object to appear equal in size to the Sun.

And don’t miss the spectacle going on around you during an eclipse as well. Projecting the disk of the Sun using a pinhole camera or binoculars onto a piece of paper makes for a great shot. Hundreds of crescents may litter the ground, caused by natural “pinhole projectors” such as gaps in leaves or latticework. And photographs of everyday folks wearing eclipse glasses standing enthralled by the ongoing event can be just as captivating as the eclipse itself.

Photo by author
Imaging a partial solar eclipse via a homemade shoebox binocular projector. Photo by author.

Up for a challenge? Another unique opportunity awaits eclipse viewers in the northwest, as the International Space Station will cross the disk of the Sun around ~21:08 UT during the eclipse. You’ll need to run video to catch such a speedy (about a second in duration) event, but it would make for a great capture! Be sure to check CALSky for predictions of ISS solar and lunar transits within 48 hours of the event.

ISS path
The path of the ISS over the US during the partial eclipse. Credit: Orbitron.

Robotic eyes in low Earth orbit will be watching the eclipse as well. JAXA’s Hinode and ESA’s Proba-2 routinely observe the Sun and will catch fleeting eclipses on successive passes on Thursday… in the case of Hinode, it may score a direct “hit” with an annular eclipse seen from space around 21:03 UT:

And don’t forget, we’re now less than three years out from the next total solar eclipse to (finally!) grace the United States from coast to coast on August 21st, 2017. This week’s partial solar eclipse offers a great test run to hone your photographic technique!

-Send those eclipse pics in to Universe Today’s Flickr forum.