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

Types of Solar Eclipses

Jeff DeTray from AstronomyBoy.com
Partial Eclipse

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

Phillip Calais/NASA

Not all solar eclipses are the same. A total solar eclipse is a very different experience than a partial solar eclipse. Let’s outline the differences.

What is a Solar Eclipse?

In all cases, a solar eclipse occurs when the Moon moves between Earth and the Sun. All three celestial objects—Earth, Moon, and Sun—are aligned. However, the alignment is not always perfectly straight.

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

  • In a total solar eclipse, the Moon completely blocks the entire disk of the Sun (as seen from Earth) so that sunlight does not reach Earth. 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.
  • In a partial eclipse, the Moon only partially covers the disk of the Sun. The three options are not perfectly aligned. The Sun appears to have a dark shadow on only a small part of its surface.

The difference between a total solar eclipse and a partial eclipse is like the difference between night and day. 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.

Partial solar eclipses are quite common. They occur every few years.

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. Because the Moon is farther away from Earth, it seems smaller than the Sun as it passes centrally across the solar disk and a bright ring, or annulus, of sunlight remains visible during the eclipse.

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.