Total Solar Eclipse Versus Partial Eclipse: What's the Difference?

Types of Solar Eclipses

By Jeff DeTray from AstronomyBoy.com
June 25, 2019
Partial Eclipse

Partial eclipse from May 13, 2013 as viewed from Fremantle, Australia.  

Phillip Calais/NASA

With the next total solar eclipse around the corner (July 2, 2019), you may wonder what’s so special about totality. The difference between a total solar eclipse and a partial eclipse is like the difference between night and day. Understand the differences …

On July 2, 2019, the world will once again have a chance to experience totality, when the moon completely blocks the sun, turning day into night. See information about The 2019 Total Solar Eclipse.

What’s the Difference Between a Total Solar Eclipse and a Partial Solar Eclipse?

In general, a solar eclipse occurs when the disk of the Moon appears to cross in front of the disk of the Sun.

  • total solar eclipse—like the one that crossed the U.S. in August, 2017—occurs when the disk of the Moon blocks 100 percent of the solar disk so that sunlight does not reach Earth. 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 if it were night. However, you can only see totality from a very narrow path on Earth (about 100 miles wide). If you don’t live in this path, you will see a partial solar eclipse.
  • partial eclipse occurs when the Moon only partially covers the disk of the Sun. 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.

Frankly, if you didn’t know a partial eclipse was happening, you might not even notice it. While astronomically interesting, the partial eclipse does not have that rare total darkness that you experience in the total solar eclipse. 

It’s only during the minutes of 100% totality that you see the Sun’s bright corona shine across the sky, pink prominences leaping, and stars emerge from the inky black sky, and other phenomena.

What is a Solar Eclipse?

Annular Solar Eclipse

There is a third type of eclipse called an annular (ANN-you-ler) solar eclipse. This occurs when the Moon is farthest from Earth (apogee), so that the Moon looks smaller than the Sun when it passes in front of the solar disk. This means that it won’t block the Sun entirely, so sky watchers will see a bright ring (annulus), turning the Sun into a blazing “ring of fire” from Earth’s perspective. 

The next “ring of fire” eclipse takes place on December 26, 2019, and it will be visible from Saudi Arabia, Qatar, India, Sumatra, Borneo, Guam and the Philippines.

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 do want to check out a solar eclipse, do NOT look at the Sun without proper filters. Do not use sunglasses. They will NOT protect your eyes! See how to safely view a solar eclipse.

Reader Comments

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Eclipse!

I GUESS i should pay more attention. I thought it was Sunday not MONDAY! Based on my results with the equipment I have I probably won't bother with the Speed Graphic just to view it. The Sony doesn't have the magnification I want but I was able to get the sun just not as clear as I had hoped.

Solar Eclipse Conn.

I viewed some Solar Eclipse; however I did not look directly at the sun; thanks for sharing the story Joe reminds me the day I began my school classes a day early; I could not figure out where all the other students were!; I thought the Eclipse was "stressful"; worrying about looking at the sun; what I did not know was the Earth is also aligned with the Sun + Moon; no wonder this happens once every hundred yrs!!!;
Anne;

Eclipse?

I used the Vox calculator which told me that for my zip code 67% of the sun would be blocked with the moon at about 2:47 pm EST. At about 2:36 the clouds parted enough to see the sun with my Speed Graphic, a Tele Peconar lens and the bellows out as far as it would go (no film just as a viewer) and never saw anything that would pass as an eclipse. I also used a Sony F828 camera with a 1000nm IR pass filter and never saw anything but a full circle of the sun.