Difference Between Total and Partial Solar Eclipse | Almanac.com

Difference Between Total and Partial Solar Eclipse

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partial vs total eclipse vs. annular

Types of Solar Eclipses

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The 2024 Old Farmer's Almanac

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When it comes to a total solar eclipse, only 100% will do. A 70% or even a 99% partial eclipse misses out completely on what totality is all about. Knowing the difference can help you plan for success—and avoid disappointment.

Don’t be fooled by the media when they announce a spectacular eclipse, as the word “eclipse” can mean a variety of things. There are partial, total, lunar, annular, penumbral, and solar eclipses. See our Eclipse Calendar for the coming year.

Most English nouns don’t suffer such ambiguity. If someone says soul-mate, rainbow, waterfall, or wedding, a clear, positive meaning is communicated. 

Take the total solar eclipse. Only those in a narrow 100-mile-or-so-wide corridor will have this rare experience. Everyone else will see a partial solar eclipse. 

Some folks will think a 70% or even a 95% eclipse is close enough—like 95% of a cherry pie. But that is NOT how totality works. It’s all or nothing—perhaps it’s like being in true love or not being in love. If you don’t understand the idea of 100% totality, you’ve misunderstood what a Total Solar Eclipse is all about.

Case in point: According to a survey of experienced observers, a partial solar eclipse is barely 1% as spectacular as a total solar eclipse. Only a total solar eclipse has the magic. That’s because an avalanche of unique effects suddenly unfolds in totality. You will only see a partial solar eclipse if you’re not living right on the slim path of totality or planning to drive to the path. 

What is a Total Solar Eclipse

total solar eclipse occurs when all three celestial objects—Earth, Moon, and Sun—are perfectly aligned. The Moon casts a shadow onto Earth, and the sky becomes very dark.

As seen from your location, the Moon crosses the Sun nearly dead center. Again, to see a total solar eclipse, you must be on the path of totality.

The magic happens within the last 15 seconds when the Moon completely covers the Sun. When it goes from 99.9% to 100% covered, it’s that 0.1% that makes all the difference. 

You can see the Sun’s bright, feathery corona, its outermost atmosphere. You may also see pink prominences leaping, stars emerging from the inky black sky, and other phenomena. See my article on a step-by-step guide to eclipse day.

A total eclipse also has a partial eclipse phase before and afterward. 

the path of a total solar eclipse
See the image above? You only see this during a total eclipse.

What is a Partial Solar Eclipse

partial eclipse occurs when the Moon only partially covers the disk of the Sun (as seen in the above sequence). The Earth, Moon, and Sun are not perfectly aligned. The Sun appears to have a dark shadow on only a small part of its surface. Partial solar eclipses are quite common. They occur every few years. 

Again, what if you saw an 85% or even a 99% eclipse? It would look like any other partial eclipse. Light and temperature levels will drop slightly, but the Moon doesn’t completely block the Sun. You’ll still be missing out on what a total solar eclipse is all and only about: Totality.

Frankly, you might not even notice if you didn’t know a partial eclipse was happening. 

What is an Annular Solar Eclipse

There is a third type of eclipse called an annular (ANN-you-ler) solar eclipse. This occurs when the Moon passes between the Sun and Earth but when the Moon is at or near its farthest point from Earth (apogee). Because the Moon is farther away, it appears smaller than the Sun and does not completely cover the Sun. As a result, the Moon appears as a dark disk on top of a larger, bright disk, creating what astronomers call a “ring of fire” around the Moon.

an annular eclipse

What is a Hybrid Solar Eclipse?

Some folks refer to a fourth type of solar eclipse called “hybrid.” It simply means that some folks will see a total eclipse, and others will see an annular eclipse based on where they live as the Moon moves across the curved globe. It’s extremely rare, so I won’t explore this one further.

What is an Umbra and Penumbra?

During a solar eclipse, the Moon casts two shadows on Earth. The first shadow is called the umbra (UM bruh). This shadow gets smaller as it reaches Earth. It is the dark center of the moon’s shadow. The second shadow is called the penumbra (pe NUM bruh). The penumbra gets larger as it reaches Earth. People standing in the penumbra will see a partial eclipse. People standing in the umbra will see a total eclipse.

Seeing an Eclipse Safely

If you want to check out a solar eclipse, do NOT look at the Sun without proper filters. Please don’t wear sunglasses. They will NOT protect your eyes! See how to safely view a solar eclipse.

About The Author

Jeff DeTray

Jeff DeTray helps to guide new star-watchers into the world of astronomy with his website, AstronomyBoy.com. He also creates beautiful in-depth sky charts for the Old Farmer's Almanac. Read More from Jeff DeTray