In the year 585 BCE, the armies of the Medes and the Lydians met one another for a battle in what is modern day Turkey. However, before the battle broke out, “... day was on a sudden changed into night.” This was interpreted as an omen by both parties, thus signaling a truce that ended the battle before it even began. It is thought by some that this was a solar eclipse, one that was predicted by Thales of Miletus: a Greek mathematician and astronomer. While there is reason to believe this story is apocryphal, it illustrates the power and fear that a solar eclipse had on unsuspecting people. After all, who could blame them? During a solar eclipse, the Sun’s warmth and light quickly vanishes, temperatures drop, and there appears to be a black hole encircled by white light in the sky where the Sun used to be.
But what is a solar eclipse? A solar eclipse occurs when the Moon passes between the Earth and the Sun, covering up our view of the Sun in the process. We live at a fortunate time in the Earth’s history; the Moon is roughly 400 times smaller than the Sun but is also 400 times closer. As a result, the Moon appears the same size as the Sun in the sky. On average, a total solar eclipse will take place about once every 18 months. There are four different types of eclipses: a partial eclipse, an annular eclipse, a hybrid eclipse, and a total eclipse. A partial eclipse occurs when the Moon only covers a fraction of the Sun’s disc. This can happen because the Sun, Moon, and Earth aren’t in precise alignment at that time, or simply because a total solar eclipse isn’t visible from your location. An annular eclipse occurs when the Moon is a little further away and appears smaller than the Sun in the sky. In that situation, it won’t completely cover the Sun’s disc and observers see a ring of light instead. It’s not unusual for annular eclipses to occur once a year, but occasionally the gap will be longer or shorter, with six or eighteen months between eclipses.
A hybrid eclipse is a combination of a total and annular eclipse. Some observers would see a total solar eclipse, while others would see an annular eclipse. It depends upon which part of the Moon’s shadow the observer is in. A hybrid eclipse is the rarest of them all: the next will be visible in April 2023. And lastly, a total eclipse is when the Sun is completely eclipsed by the Moon. The next total solar eclipse that will be visible over the United States will be in April 2024.
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Interested in learning more about the different types of eclipses? Not sure where to begin? Check out our Astronomy Hub!
