The only annular eclipse of 2021 will produce a fine spectacle across most of North America and Europe.

Got those solar glasses handy from 2017? If skies are clear on the morning of Thursday June 10th, you may once again find good use for them, as an annular ‘ring-of-fire’ eclipse crosses northeastern Canada into the Arctic.

Annular eclipses occur when the Moon is visually too tiny to completely cover the Sun. You can see how circumstances are stacking up in favor of an annular versus a total solar eclipse in early June, as the Earth reaches aphelion (its farthest point from the Sun) just a few weeks later on July 5th, while the Moon reaches apogee on June 8th, just 46 hours prior to the eclipse. On June 10th, the Moon appears 29’ 34” across, versus the Sun’s 31’ 30” diameter.

The viewing footprint with the path of annularity and contact times (in Universal Time) for the June 10th annular solar eclipse credit: courtesy Michael Zeiler, author of the Atlas of Solar Eclipses 2020 to 2045.

The annular shadow of the Moon is the central cone where the ring of fire can be seen. This is known as the antumbra of the Moon.

And while the folks often tout the ‘perfection’ of total solar eclipses as seen from the Earth, in the current epoch, annulars are actually more common, and will become increasingly more so. This is because the Moon is slowly moving away from us, currently to the tune of about 3.8 centimeters per year. About 900 million years ago, the very first annular eclipse occurred, and 1.4 billion years from now the last total solar eclipse will grace the Earth, after which, all central solar eclipses will be annular.

An animation of the June 10th annular solar eclipse. Credit: A.T. Sinclair/NASA/GSFC

Now, for the bad news: the path for annularity of this eclipse is a bashful one, passing over remote regions of the Canadian province of Ontario, Hudson Bay, northern Quebec and Northwestern Greenland before crossing the North Pole and ending at dusk on the Arctic shores of Siberia. Overall, the central path is pretty sparsely populated, though the military stations of Alert, Canada and Thule Air Base in Greenland are in the path. Another factor clipping the wings of many an eclipse tourist is the fact that, as of writing this, the U.S.-Canada border is still closed due to the ongoing pandemic at least until June 21st.

The eclipse at sunrise, as seen from four selected locales. Credit: Stellarium.

Viewing region and prospects – The good news is, millions across the northeastern half of North America, nearly all of Europe and Russia will see various stages of a partial solar eclipse. For the contiguous United States (CONUS), the line to catch a partial eclipse at sunrise runs through the Dakotas right down to Georgia… but the ‘sweet spot’ for a particularly photogenic ‘sunrise horns’ eclipse runs through the Great Lakes, right down through the New Jersey-Pennsylvania/Delaware tri-state region.