A Sunrise Annular Solar Eclipse – Sky & Telescope


Annular eclipse
Kevin Baird captured the May 20, 2012, annular eclipse moments before the crescent closed into a ring of fire. June’s eclipse will make for excellent photo opportunities with the Sun near the horizon from many U.S. and Canadian locations.
Kevin Baird

The dance goes on. Two weeks after May’s total lunar eclipse, the Sun, Moon and Earth align again on Thursday, June 10th. This time, the Moon glides between the Earth and the Sun to grace the morning sky with an annular eclipse. The eclipse is central but not total because the Moon is near apogee, its most distant point from Earth. Its apparent diameter of 29.5′ will be two arcminutes shy of completely covering the Sun, leaving an arcminute-wide “ring of fire” at maximum eclipse.

Path of Annularity of the June 2021 Eclipse
The path of annular eclipse crosses the wilds of Canada, Greenland, and Russia. Elsewhere, partial phases are visible across the eastern third of the U.S. as well as much of Europe and Asia. Greatest eclipse occurs just off the coast of Greenland where gulls and seals will witness a ring of sunlight lasting 3 minutes 51 seconds.
Sky & Telescope

The Moon’s shadow strikes the Earth at an oblique angle during the upcoming eclipse, cutting a broad path that starts along the north shore of Lake Superior in Ontario and passes over Hudson Bay and northwestern Greenland before moving on to Russia. It even includes the North Pole, where 2 minutes 36 seconds of annularity will interrupt more than 2 ½ months of continuous daylight. Anyone living within this expansive strip — and there aren’t many! — will see a ring or annulus of sunlight at maximum eclipse.

Geometry of annular solar eclipse
During a total solar eclipse, the Moon’s shadow cone (umbra) extends all the way to the Earth’s surface and blocks the Sun from view. In an annular eclipse the Moon is at or near apogee, and the lunar disk appears too small to cover the Sun. Observers situated in the antumbra — where the eclipse is annular — see a ring of sunlight instead.
Eclipse Predictions by Fred Espenak, www.EclipseWise.com

COVID-19 Hurdles

Eclipse enthusiasts who hoped to drive north for the event won’t be able to cross into Canada due to COVID-19 restrictions in place until at least June 21st. One way around this is to fly into the eclipse path. To that end Sky & Telescope has chartered a flight into southern Ontario on the big day. There are still a few seats left as of this writing. Click here for more information.

Path of Annularity of the June 2021 Eclipse over Canada
The icons in this close-up map show the depth of the eclipse visible from various cities. Within the negative path of annularity maximum annular eclipse occurs shortly before sunrise. Observers in this zone should be alert for unusual twilight effects and possibly oddly lit clouds in the eastern sky.
Gregg Dinderman / S&T

Meanwhile, a large swath of the eastern U.S. and Canada along with observers across much of Europe and Asia will witness the eclipse’s partial phases. For millions of Americans the Sun will rise steeped in a deep partial eclipse. It goes without saying you’ll need an unobstructed northeastern horizon to see it best. If possible, try to watch the eclipse from a lake where the blazing crescent and its glitter path should be nothing short of spectacular. Check out this video made on May 10, 2013, to see just how amazing a sunrise annular eclipse can be.

Safe eclipse viewing
Mylar eclipse glasses offer a safe, easy way to observe a solar eclipse. Another method is to project the Sun’s image through one half of a pair of binoculars onto a white sheet of paper (left). Small openings between the leaves on trees (or crossed fingers, right) will project tiny images of the eclipsed Sun on the ground below.
Bob King (left, center) and Sealle / CC BY-SA 4.0 (right)

Many of us will be tempted to look at the rising Sun at the horizon where haze often attenuates its light. Be careful. A momentary glance might be OK, but never stare at the Sun even for a second. Infrared light can cook your retinas and permanently damage your vision. Keep eclipse glasses at the ready. If you purchased a pair for the 2017 total eclipse, inspect them for wear and tear. As long as they’re not scratched up or full of pinholes you can reuse them for this eclipse. If you need a fresh pair, try one of these. Another good option is an inexpensive #14 welder’s glass from a welding supplier in your city or region.

Do-it-yourself eclipse predictions

Boston eclipse particulars
This image from the Interactive Solar Eclipse Map features the circumstances for Boston, Massachusetts. The sunrise time and percent obscuration at that moment are highlighted in black. The time and obscuration of maximum eclipse (72.847%) are highlighted in red. For locations where maximum eclipse occurs before sunrise, the obscuration at the time of sunrise appears in the Sunrise (RISE) line (see example below).
Xavier M. Jubier

The table (below) lists eclipse circumstances for 20 cities, but you can easily get all the details of your local circumstances at Xavier Jubier’s Interactive Solar Eclipse Map. Zoom in to the map and click on where you plan to watch the eclipse. A box will pop up that includes the time of sunrise and the percent of the Sun’s disk obscured by the Moon. Note that times are in Universal Time (UT). To convert to EDT, subtract 4 hours; 5 hours for CDT; 6 for MDT; and 7 for PDT. For a full explanation of each line in the pop-up box, click the blue Help link.

Chicago eclipse particulars
The obscuration value (left) will display “???” if the Sun is below the horizon at maximum eclipse. This will be true in places like Chicago, where the Sun will rise 28.78% covered.
Xavier M. Jubier

I’m especially interested in this eclipse because I live in the negative path of annularity, where the Sun will be in annular eclipse shortly before sunrise. I’m envisioning a bizarre twilight that begins normally but then stalls as annularity approaches before resuming its normal (though perhaps muted) progression just before sunrise. The quality of the light during this time should be fascinating to watch as well as any effects the solar annulus might have on clouds along the eastern horizon.

Negative annularity view
Duluth, Minnesota, lies in the negative annularity zone with the Sun in annular eclipse 3.8° below the horizon shortly before it rises.
Stellarium
Eclipse viewing sample locations
Here are a few examples of the Sun’s appearance from five different cities. The Armstrong, Ontario, illustration shows the Sun shortly after local sunrise at the time of maximum eclipse. The others show the local sunrise time, maximum obscuration (in all instances at or shortly before sunrise), and the time the partial eclipse ends.
Stellarium

From many central U.S. and southern Canada locations the maximum obscuration occurs before sunrise, so the best views will be just as the Sun comes up with the Moon’s egress underway. Locations farther east will see maximum eclipse after sunrise. The diagrams show the percentage obscuration, which is the fraction of the Sun’s area covered by the Moon. Charleston, South Carolina, is the largest and southernmost U.S. city to see a partial eclipse, with the Sun just 4.6% covered when it fully clears the horizon.

Circumstances around the planet

City Sunrise/sunset Max. eclipse Obscuration Alt. End of eclipse
Fairbanks, AK 3:09 a.m. 2:50 a.m. 50.1% at sunrise –0.3° 3:44 a.m.
Thunder Bay, ON 5:56 a.m. 5:53 a.m. 85.4% at sunrise –0.3° 6:50 a.m.
Chicago, IL 5:16 a.m. 4:44 a.m. 28.8% at sunrise –0.3° 5:39 a.m.
Detroit, MI 5:56 a.m. 5:41 a.m. 60.6% at sunrise –0.3° 6:38 a.m.
Ottawa, ON 5:40 a.m. 80.1% 3.2° 6:40 a.m.
Quebec City, PQ 5:40 a.m. 78.9% 6.5° 6:41 a.m.
Pittsburgh, PA 5:50 a.m. 5:36 a.m. 60.7% at sunrise –0.3° 6:33 a.m.
Charlotte, NC 6:09 a.m. 5:31 a.m. 16.8% at sunrise –0.3° 6:26 a.m.
New York, NY 5:33 a.m. 72.5% 6:31 a.m.
Cambridge, MA 5:33 a.m. 72.9% 3.5° 6:33 a.m.
Reykjavik, IS 10:17 a.m. 60.5% 38.5° 11:33 a.m.
Dublin, IE 11:09 a.m. 28.5% 50.3° 12:22 p.m.
London, UK 11:13 a.m. 20.0% 54.9° 12:23 p.m.
Madrid, ES 11:43 a.m. 4.8% 53.9° 12:29 p.m.
Venice, IT 12:26 p.m. 2.2% 65.9° 1:05 p.m.
Vienna, AT 12:40 p.m. 4.4% 64.7° 1:28 p.m.
Helsinki, FI 2:04 p.m. 26.8% 52.1° 3:15 p.m.
Moscow, RU 2:26 p.m. 15.7% 50.8° 3:28 p.m.
Beijing, CN 7:43 p.m. 8:19 p.m. 7.6% at sunset –0.3°
This table includes a sample of cities where the partial solar eclipse will be visible. All times are local. Sunrise occurs when the upper limb of the Sun first appears at the horizon. Sunrise/sunset times are listed where relevant. Altitude values include the effects of atmospheric refraction. For cities where the maximum viewable eclipse occurs at sunup, the amount of obscuration will be several percent less than the values shown once the solar disk clears the horizon approximately 4 minutes later.
Source: Xavier M. Jubier

For now, I’m aware of two livestreams (below) for watching the eclipse online. If you hear of others, please let me know, and I’ll add them. Check here for solar eclipse photo tips, and remember to share the event with family and friends. It feels good to finally come out of our COVID-19 shells into the sunshine.

Annular eclipse at dawn
The Sun rises in annular eclipse on May 10, 2013, as seen from Western Australia. Note the slight elongation of the Sun’s disk and the lunar silhouette due to atmospheric refraction near the horizon. Telescope users in or near the path of annularity should watch for weird diffraction effects as lunar peaks “stretch” towards the Sun’s inner limb at second and third contacts, when the lunar limb is tangent to the Sun’s inner limb. Prominences might also be photographed at these times.
Geoff Sims & Colin Legg

Livestreaming options:

Timeanddate.com YouTube starts June 10th, 3 a.m. CDT (8 a.m. UT)
CosmoSapiens YouTube, starts June 10th, 2 a.m. CDT (7 a.m. UT)


If you’re interested in reading more about this and other celestial events this month click here to purchase a copy of the June 2021 issue of Sky & Telescope.


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