It’s Showtime! April’s Total Solar Eclipse Is Upon Us

The day we’ve been impatiently waiting for is here! Eclipse enthusiasts of all stripes have been anticipating the dawning of April 8, 2024, when the Moon will pass directly between Earth and the Sun as seen from North America. The new Moon will fully block the Sun’s bright face, turning day into deep twilight and revealing the magnificent solar corona, our star’s wispy outer atmosphere. Our natural satellite’s dark shadow, about 115 miles wide, will cross Mexico, sweep from Texas to Maine, and then darken parts of eastern Canada. Tens of millions of people within the path will experience a total solar eclipse — at least the midday darkness, and a stunning view of the corona if skies are clear. Outside this narrow path, nearly everyone on the continent will get a chance to witness a partial solar eclipse, which is not nearly as awe-inspiring as a total one but still better than no eclipse at all.

Where to See the Eclipse

From beginning to end, a solar eclipse lasts up to about three hours. For most of that time, the Moon slowly covers the Sun, then uncovers it; these are the eclipse’s beginning and ending partial phases. The real excitement comes in the middle, but only for those within the narrow path of the Moon’s dark shadow, and only for a few precious, fleeting minutes.

You can experience a total solar eclipse only if you’re within the path of totality, a narrow ribbon arcing thousands of miles across Earth’s curved surface. The path of totality is the track of the dark shadow cast by the Moon as it moves in its orbit. Outside this path, no matter how close you are to it, you’ll only experience a partial solar eclipse. Some places along the path of totality are more likely than others to have clear skies, but anywhere within the path is better than anywhere outside the path. A total solar eclipse experienced under cloudy skies is more exciting than a partial solar eclipse seen under clear skies.

“If you can get yourself into the path of the Moon’s shadow for a total solar eclipse, it’s definitely worth the effort,” says Rick Fienberg, Project Manager of the American Astronomical Society (AAS) Solar Eclipse Task Force and Senior Contributing Editor of Sky & Telescope. “A 99% partial solar eclipse doesn’t get you 99% of the experience of a total solar eclipse — the last 1% is the difference between night and day. As the Moon blots out the thinning arc of the bright Sun in the final minute before totality, daylight fades by hundreds of times. And the solar corona surrounding the Moon’s velvety black silhouette is one of the most glorious sights in all of nature!”

During a total solar eclipse you’ll experience many other noteworthy phenomena, including a drop in air temperature, changes in wind speed and direction, bright planets and stars shining in deep twilight, ruby-red solar prominences (eruptions of hot gas protruding beyond the limb, or edge, of the Sun’s hidden disk), pastel sunrise/sunset colors around the horizon, and animals, birds, insects, and perhaps even plants behaving as if the Sun has set. Another total solar eclipse won’t cross the U.S. until August 12, 2045, so this April’s event is your best chance to catch totality here for a generation.

The following table gives the local circumstances for select cities in the U.S., Mexico, and Canada within the path of totality.

All times are local daylight-saving time. Source: RASC Observer’s Handbook. 

Eye Safety Is Paramount

The totally eclipsed Sun is about as bright as a full Moon in the sky and is just as safe to look at directly without eye protection, even through binoculars or a telescope. But during the partial phases, the Sun remains dangerously bright at all times and must never be looked at directly except through special-purpose “eclipse glasses” or handheld solar viewers that meet the requirements of the ISO 12312-2 international standard. The American Astronomical Society’s webpage on eye safety has valuable advice on where to get safe solar filters and on indirect viewing methods. During totality, you can and should remove your eclipse glasses or solar viewers — otherwise you won’t see anything at all!

Eclipse glasses and handheld solar viewers are meant to be used only with your eyes. Never look at the Sun through an unfiltered camera, telescope, binoculars, or any other optical device while using your eclipse glasses or handheld solar viewer — the concentrated solar rays could damage the filter and enter your eyes, causing serious injury. Solar filters must be attached to the front of any telescope, binoculars, camera lens, or other optics.

Eclipse Geometry

We get solar eclipses because, by an amazing 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 rather than 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 can be up to 14% larger than when it’s farthest (apogee); again, this effect is not too noticeable. When the Moon is closer than average and the Sun farther away than average, as will be the case on April 8th, the Moon can easily cover the entire solar disk and unveil the ethereal corona.

You might wonder why we don’t have a solar eclipse at every new Moon. This is because the Moon’s orbit around Earth is tipped by about 5° 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 — including an annular eclipse crossing Chile and Argentina on October 2nd this year. Whether a solar eclipse is partial, annular, or total depends on how precisely the Sun, Moon, and Earth align and on the distances of the Moon and Sun from Earth.

Travel Advice

When traveling to an observing site in the path of totality, you should arrive early, stay put, and leave late — otherwise you’re likely to get stuck in a massive traffic jam, possibly causing you to miss totality altogether. Traffic is worst right after totality ends, when many observers pack up and leave all at once. Most eclipse-watching events offer entertainment or other activities after the eclipse. Stick around for those so you’ll have an easier and quicker trip home.

Eclipse Info in Your Pocket

The AAS (Sky & Telescope’s publisher), Big Kid Science, and the American Institute of Physics (AIP) have teamed up to produce version 4.0 of the Totality app, which is free for iOS and Android smartphones. Features include interactive maps and detailed eclipse circumstances for all total solar eclipses from 2024 to 2030 as well as useful information on eye safety and on how and why eclipses occur. In addition, the app taps into your phone’s GPS not only to show what you can see at your current location, but also to advise you on the nearest location where you can witness totality — and give you driving directions. It’s also ad-free, for a seamless and enjoyable eclipse-exploring experience. You can learn more about Totality and other eclipse apps on Sky & Telescope’s website.

More Information

A thorough review of the April 2024 total solar eclipse appears in a special Sky & Telescope issue dedicated to the event, The Great 2024 Eclipse, available for purchase online and at select newsstands. The April 2024 issue of Sky & Telescope magazine contains a succinct summary and is also available online and on newsstands.

The Sky & Telescope website continues to provide updated information through its dedicated April 2024 eclipse webpage.

The American Astronomical Society’s Solar Eclipse Task Force has collated important logistics advice and eye-safety information in one handy website.

You can get local circumstances of upcoming solar (and lunar) eclipses for cities worldwide on TimeandDate.com’s Eclipses page.

Contacts

Susanna Kohler

AAS Communications Manager & Press Officer

+1 202-328-2010 x127

Email

Diana Hannikainen

Observing Editor, Sky & Telescope

+1 617-500-6793 x22100

Email

Rick Fienberg

Project Manager, AAS Solar Eclipse Task Force

+1 857-891-5649

Email