Two Solar Eclipses Are Coming to America
The countdown has begun! Exactly one year from today, the first of two major solar eclipses just six months apart will occur over the Americas. On 14 October 2023, the Moon will pass directly between Earth and the Sun but will cover only 90% of the brilliant solar disk. The remaining 10% will appear as a blazing “ring of fire” around the Moon’s dark silhouette. This annular (Latin for ring-shaped) solar eclipse will be visible within a roughly 125-mile-wide path from Oregon to Texas and on into Mexico, Central America, and northern South America. Outside this path, nearly everyone in North America will have a partial solar eclipse.
Then, on 8 April 2024, we’ll have a total solar eclipse like the one that crossed the U.S. from coast to coast on 21 August 2017. As it did that day, the Moon will fully block the Sun’s bright face, turning day into night for several minutes and revealing the magnificent solar corona, our star’s wispy outer atmosphere. This time the Moon’s shadow, about 115 miles wide, will cross Mexico, sweep northeast from Texas to Maine, and then darken the Canadian Maritimes. Most of the rest of North America will have another partial solar eclipse.
Where and How to See Them Safely
From beginning to end, a solar eclipse lasts up to about 3 hours. For most of that time, the Moon slowly covers the Sun, then uncovers it, and the eclipse is partial. The real excitement comes in the middle, but only for those within the narrow path of the Moon’s shadow. In April 2024 the Moon’s shadow will pass over more big cities than in 2017 and give at least 30 million Americans a shot at seeing the solar corona without having to travel. But there’s a catch: in early April much of the country is still in winter’s grip. Clear skies are most likely across Mexico and Texas Hill Country, so those are the places where many ardent eclipse enthusiasts plan to go. Weather prospects for the October 2023 annular eclipse look most promising in parts of Utah, New Mexico, and Texas. Sky & Telescope offers package tours to the best places to see both eclipses (skyandtelescope.org/tours).
During partial and annular solar eclipses, the Sun remains dangerously bright at all times and must never be viewed directly except through special-purpose “eclipse glasses” or handheld viewers that comply with the ISO 12312-2 international standard. See eclipse.aas.org/safety for advice on where to get safe solar filters and on indirect viewing methods. During the brief total phase of a total solar eclipse, you can safely view the eclipsed Sun without eye protection.
“If you can get yourself into the path of the Moon’s shadow for a total eclipse, it’s definitely worth the effort,” says Rick Fienberg, Project Manager of the American Astronomical Society’s Solar Eclipse Task Force. “A 99% partial solar eclipse doesn’t get you 99% of the experience of a total solar eclipse — that last 1% is literally the difference between night and day. As the Moon covers the last 1% of the Sun over the course of a minute or so, daylight fades by 10,000 times. And the solar corona is one of the most glorious sights in all of nature!”
For the annular eclipse in 2023, observers under clear skies within the path of the Moon’s shadow from Oregon to Texas will see the “ring of fire” for up to 5 minutes. For the total eclipse six months later, totality — when the Moon fully obscures the Sun, the temperature drops, bright stars and planets dot the daytime sky, and sunrise/sunset colors ring the horizon — lasts nearly 4 minutes 30 seconds at the U.S. border with Mexico and about 3 minutes 20 seconds at the border with Canada.
Another total solar eclipse won’t cross the U.S. until August 12, 2045, so the April 2024 event is your best chance to catch totality for a generation.
The AAS Solar Eclipse Task Force, which is helping to coordinate nationwide planning, is hosting a hybrid (in-person + virtual) solar eclipse planning workshop Friday-Saturday, 21-22 October 2022, at the Rochester Museum & Science Center (RMSC), 657 East Ave., Rochester, NY 14607 (eclipse.aas.org/workshops/oct2022). The theme is “Preparing Your Community for the Coming Solar Eclipses.”
The workshop is for everyone involved (or wanting to become involved) in preparing their community for the upcoming North American solar eclipses, whether on or off the eclipse path(s). Attending will be more than 150 amateur and professional astronomers; formal and informal educators; local, state, and national government officials; representatives from the tourism and hospitality industries; professionals in health, safety, transportation, and emergency management; local, state, and national park rangers; and artists, filmmakers, science writers, and event planners.
We get solar eclipses because, by a remarkable cosmic coincidence, the Sun and Moon appear almost exactly the same size in our sky. The Sun’s diameter is really about 400 times bigger than the Moon’s, but the Sun is also about 400 times farther away. Because Earth’s orbit around the Sun and the Moon’s orbit around Earth are both ellipses, not perfect circles, the apparent sizes of the Sun and Moon vary a little during the year (Sun) and during each month (Moon).
Our planet is closest to the Sun (perihelion) in early January and farthest (aphelion) in early July, and the Sun appears about 3% wider in January than in July — not that you’d notice. When the Moon is closest to Earth (perigee), its apparent diameter is about 11% larger than when it’s farthest (apogee); again, this effect is not too noticeable. When near perigee, the Moon can easily cover the entire solar disk and unveil the ethereal corona. But near apogee the Moon is too small to fully cover the Sun’s face, so at mideclipse a brilliant annulus (ring) of sunlight encircles the lunar silhouette.
You might wonder why we don’t have a solar eclipse at every new Moon. It’s because the Moon’s orbit around Earth is tipped about 5 degrees to Earth’s orbit around the Sun (which, from our perspective, is the Sun’s annual path through the zodiacal constellations). At new Moon, our natural satellite usually passes above or below the Sun. But twice each year, currently in April and October, the new Moon does pass in front of the Sun, so we get solar eclipses. Whether they’re partial, annular, or total depends on how precisely the Sun, Moon, and Earth align and on the distances from Earth to the Sun and Moon.
North America will soon be treated to two major solar eclipses, when the Sun, Moon, and Earth align. On 14 October 2023, anyone under clear skies within a path that sweeps from Oregon to Texas and then through parts of Central and South America will see an annular ("ring") eclipse. Just six months later, on 8 April 2024, a total solar eclipse will sweep from Mexico to Texas to the Canadian Maritimes, plunging day into night and revealing the magnificent solar corona for anyone fortunate to be within the path of totality and under clear skies. Nearly everyone in North America will have a partial solar eclipse both days. Map by Michael Zeiler (GreatAmericanEclipse.com); courtesy American Astronomical Society.
Annular solar eclipse:
The annular solar eclipse of 10 May 1994, as seen from Ogunquit, Maine. The sky appears black because the photograph was made through a safe solar filter, which blocks all but 1 part in 100,000 of the Sun’s light. Photo by Rick Fienberg; courtesy Sky & Telescope and American Astronomical Society. This photo and the one below, of a total solar eclipse, are at the same scale.
Total solar eclipse:
The total solar eclipse of 21 August 2017, as seen from Madras, Oregon. This is a composite of short, medium, and long exposures. No single photo can capture the huge range of brightness exhibited by the solar corona, which is sculpted by the Sun’s magnetic field. Several red solar prominences (eruptions of glowing hydrogen gas) are visible, as are a couple of stars. Photo by Rick Fienberg, processing by Sean Walker; courtesy TravelQuest International and Sky & Telescope.
For skywatching information and astronomy news, visit SkyandTelescope.org or pick up Sky & Telescope magazine, the essential guide to astronomy since 1941. Sky & Telescope and SkyandTelescope.org are published by the American Astronomical Society, along with SkyWatch (an annual beginner's guide to the night sky) as well as books, star atlases, posters, prints, globes, apps, and other products for astronomy enthusiasts.
The American Astronomical Society (AAS), established in 1899, is a major international organization of professional astronomers, astronomy educators, and amateur astronomers. Its membership of approximately 8,000 also includes physicists, geologists, engineers, and others whose interests lie within the broad spectrum of subjects now comprising the astronomical sciences. The mission of the AAS is to enhance and share humanity’s scientific understanding of the universe as a diverse and inclusive astronomical community, which it achieves through publishing, meetings, science advocacy, education and outreach, and training and professional development.