Total solar eclipses happen every 18 months. So why is this one rare?

BUFFALO, N.Y. — Total solar eclipses — when skies darken as the moon moves between the Earth and the sun — happen roughly every 18 months.

So why all the hype about the eclipse coming up on Aug. 21?

As a scientific phenomenon, “eclipses are not intriguing at all,” says cosmologist Dejan Stojkovic, PhD, a professor of physics in the University at Buffalo College of Arts and Sciences.

He explains that whenever the Earth, moon and sun align to form a solar eclipse, the event is visible somewhere on Earth. As the moon travels along in space, its shadow moves across the Earth's surface, and areas that fall under the darkest shadow observe a total eclipse, while areas that lie under the partial shadow observe a partial eclipse.

However, the Aug. 21 event is generating huge interest in the United States because it will be viewable across the country — which is somewhat unusual, Stojkovic says.

The “path of totality” — which covers regions under complete shadow — varies from one eclipse to the next, and a total solar eclipse has not made landfall over the contiguous United States since 1979.

On Aug. 21, “the path of totality will stretch all the way from Oregon to South Carolina,” Stojkovic says. “Buffalo does not lie exactly on the path of totality, but a good part of the sun will be blocked in our area too. So if the weather permits, we should be getting a pretty good look of the eclipse.”

With regard to humanity’s fascination with solar eclipses, Stojkovic adds, “Our sun is directly related to all forms of life on Earth, so its disappearance, even for a few minutes, was historically associated with some dire predictions — like natural catastrophes, big wars, deaths of kings, etc.

“While this phenomenon is not mysterious at all from a scientific perspective, it is still very impressive to watch the power of nature at work — of course, with all the safety precautions.”

Stojkovic is available for phone or in-person interviews from Aug. 10-12, and by email the week of Aug. 14.