Total Solar Eclipse Versus Partial Eclipse: What's the Difference?
Partial eclipse from May 13, 2013 as viewed from Fremantle, Australia.
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Types of Solar Eclipses
Jeff DeTray from AstronomyBoy.com
November 12, 2021
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 …
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.
A 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.
A 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.
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.