Total Solar Eclipses: How Often Do They Happen?

How Rare is a Total Solar Eclipse?

Jeff DeTray from AstronomyBoy.com
Total Solar Eclipse Sequence

The total solar eclipse of November 14, 2012, as seen from aboard the cruise ship Paul Gauguin in the South Pacific near New Caledonia. This sequence runs from lower right to upper left. During the partial phases before and after totality, the camera lens was covered by a safe solar filter. No filter was used during totality, which is about as bright as the full Moon and just as safe to look at. The background is an unfiltered, wide-field view of the ocean and sky during totality, showing sunrise/sunset colors along the horizon.

Rick Fienberg/TravelQuest International/Wilderness Travel

On August 21, 2017, people in a large swath of North America will have the opportunity to view a total solar eclipse. This month, I will forgo my usual sky map to showcase a map of the eclipse’s path and focus on this rare astronomy event. How rare is it? I’ll share some facts about that, too.

How Often Does a Total Solar Eclipse Occur?

A total solar eclipse is visible from somewhere on Earth about every 18 months. However, many of these events can be seen only from remote locales where travel is difficult.

In terms of the United States, the August 21, 2017 total solar eclipse is the first to traverse the country in nearly a century. The last time a total solar eclipse occurred in the Lower 48 was 1979—and that was only visible from a few states in the Pacific Northwest.  This 2017 eclipse will cross the country from coast to coast.

The next time a total solar eclipse will traverse from coast to coast will be in 2045.

How About the Town Where You Live?

A better question is: How often is a total solar eclipse visible from any given location, such as the town where you live?

The answer is about once every 375 years, on average.

Every location, however, is different. By chance, some locations are treated to total solar eclipses only a few years apart.

  • In the last 100 years, some areas have been in the paths of multiple eclipses: New England, for example, saw five. 
  • In New York City, the last total solar eclipse was in 1925.
  • Chicago has not seen a total solar eclipse in the last 100 years.
  • On the west coast, San Diego was last eclipsed in 1923.
  • The city of Los Angeles is in the midst of a “dry spell” of more than 1,500 years without a total solar eclipse.
  • The location with the longest dry spell is near Tucson; the last solar eclipse was in the year 797.

In other words, don’t bother waiting for the “next one.” Enjoy the rare 2017 eclipse if you can get to the path of totality—or even the live coverage. It’s only two minutes of your lifetime!

Total Solar Eclipse Path

While the 2017 Total Solar Eclipse will cross the entire United States, only viewers fortunate enough to be in the narrow Path of Totality will see a TOTAL eclipse. 

The approximately 100-mile wide shadow of the Moon will sweep across the continent from Oregon (10:15 a.m.) to South Carolina (2:45 p.m.) and will completely hide the Sun for more than two minutes.

Outside the Path of Totality, the rest of North America will see the PARTIAL eclipse. The Sun appears to have a dark shadow on only a small part of its surface. You might not even have even noticed this event.

NASA has prepared an excellent Interactive Total Solar Eclipse Map displaying the Path of Totality as well as locations that will see partial eclipses. For a general idea of the eclipse’s path, see the simplified map, below.

Map of the 2017 total solar eclipse by NASA.

Click here for an enlarged view of the above map.

Total Solar Eclipse Safety

The only time it is ever safe to look at the Sun with your “naked” eyes is during the brief minutes of totality, when the Moon has completely covered the Sun.

WARNING: NEVER LOOK AT THE SUN WITH YOUR UNPROTECTED EYESNEVER LOOK AT THE SUN THROUGH AN UNMODIFIED TELESCOPE OR BINOCULARSBOTH CAN RESULT IN PERMANENT EYE DAMAGE AND EVEN BLINDNESS.

How do you safely view the eclipse, then? Here are three ways, none costing more than a few dollars.

  1. Watch on the Web. Many web sites will offer live coverage of the eclipse. If it happens to be cloudy in your area on August 21, the web may be your only option. Try NASA’s eclipse site.
  2. Use Eclipse Glasses. For direct viewing, consider getting a pair of inexpensive eclipse glasses, which are readily available across the internet.
  3. Build an Eclipse Viewer. Essentially a pinhole camera, it’s as simple as two pieces of cardboard and a small square of aluminum foil. See NASA’s guide: How to Make a Pinhole Camera.

Do not be tempted to use sunglasses. They will NOT protect your eyes! Read more about how to safely view the 2017 total solar eclipse without damaging your eyes. Play it safe, and enjoy the eclipse on August 21!

For all your eclipse information, see the Almanac’s Total Solar Eclipse 2017 Guide!

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