Mathematics Of A Total Solar Eclipse Answers

Solar Eclipse Explained: Definition, Diagram, and History

On Monday, August 21, 2017 , people all over the United States will have the opportunity to witness something that hasn't been seen on American soil for decades and is one of Mother Nature's most awe-inspiring events.

In case you haven't already heard, that event is a total solar eclipse, one that people everywhere from Oregon to South Carolina will be able to view in all its celestial majesty.

Solar Eclipse Explained: Definition, Diagram, and History

As a tribute to this incredible astronomical event, the purpose of this post is to tell the grand narrative of the solar eclipse, from both a scientific and a cultural perspective. In it, you'll read about the following topics:

An accessible yet scientific explanation of the solar eclipse
An overview of the much anticipated "Great American Total Solar Eclipse"
Historically significant occurrences of solar eclipses
The different ways in which people have interpreted the solar eclipse over time

After reading our brief history of this fascinating astronomical phenomenon, you'll hopefully have a deeper appreciation of the beauty of the natural world. We also hope that you'll see that a scientific understanding of the natural world does not, as some opponents of science claim, decrease the level of wonder, awe, and mystery that you experience while witnessing one of its spectacular events. In fact, as you'll discover if you view the coming total solar eclipse through the lens of your new understanding, true knowledge increases the inherent beauty of the world exponentially.

An Explanation of the Eclipse from the General to the Particular

Before we dig into a more particularized explanation, let's have a look at the phenomenon known as an eclipse, a term that comes from the Greek ekleipein or " to fail to appear." The etymology of the word eclipse is of special interest here because its Greek root mirrors the early belief that whenever a heavenly body was 'eclipsed,' it had actually disappeared.

Solar Eclipse Explained: Definition, Diagram, and History

In general terms, an eclipse is an astronomical phenomenon that happens when a heavenly body such as a moon, planet, or star is briefly obscured from view. An eclipse occurs under two different sets of circumstances. The first is when the obscured heavenly body moves into the shadow of another heavenly body. The second is when this second heavenly body moves into a position between the obscured body and the viewer.

As you can see from the definition, if humans could live on heavenly bodies other than earth, the number of possible eclipses is almost limitless. But since we remain earthbound (at least so far!), there are only two general types of eclipses we can see from our limited vantage – the lunar and the solar eclipses. What many people don't know is that lunar and solar eclipses always come in pairs, one following the other within about a two week period.

Beyond that, a simple internet search will help you learn more about lunar eclipses, but here we'll be discussing the solar variety exclusively. Now let's narrow our focus a bit on talk in a bit more detail about the in and outs of the solar eclipse.

The Solar Eclipse Explained

A complete and rigorous explanation of the solar eclipse is well beyond the scope of this article, but a more general account of the causes and conditions surrounding this magnificent astronomical event will suffice for our purposes.

A solar eclipse happens when the moon passes between the sun and the earth and the moon partly or completely blocks the sun. Because the orbit of the moon around the earth is elliptical (as opposed to circular), a solar eclipse can only occur at 'new moon,' when the sun, the moon, and the earth are aligned in an arrangement called a syzygy.

When this arrangement occurs, the moon casts its shadow over parts of the earth and partial or complete darkness ensues, depending on the type of solar eclipse. There are four types of solar eclipses. First, there's the total solar eclipse, which is usually only visible in a small part of the earth's area and requires that the sun, the moon, and the earth be in a direct line.

The second type is a partial solar eclipse. These occur when the moon is between the sun and the earth, but the three bodies are not in a direct line. During a partial solar eclipse, a small part of the sun seems to covered in shadow.

The third type is called an annular solar eclipse. When an annular solar eclipse happens the moon is at its furthest point from the earth and in the direct line syzygy position with the earth and the moon. At shorter distances, this would result in a total solar eclipse, but because the moon seems so much smaller than the sun, an annular eclipse makes the sun look like a blazing ring around the darkness of the moon.

The last type of solar eclipse is known as a hybrid or annular/total eclipse. The rarest type of solar eclipse, the hybrid eclipse shifts between a total and a partial eclipse depending on your location. Next, we'll explain the difference between the two types of locations.

Another factor in how the eclipse appears on the earth has to do with the fact that he moon casts two different shadows during the event, one is named the umbra, and the other known as the penumbra. The umbra is the dark middle of the moon's shadow, while the penumbra is the part that surrounds this dark center. People in the umbra experience a total eclipse, while those in the penumbra witness a partial one.

In the next section, we'll examine some of the most famous or influential solar eclipses in recorded history.

Notable Solar Eclipses Throughout History

Now that we've considered solar eclipses from a scientific perspective, let's continue by 'viewing' them through a more historical lens, one that will reveal much about both the essence of human nature and the collective transformation from a superstitious worldview to a scientific one. Here are five of the most notable solar eclipses in recorded history.

Solar Eclipse Explained: Definition, Diagram, and History

One of the earliest recorded solar eclipses occurred in 1223 BCE, in a region of modern day Syria then known as Uragit. The Uragit Eclipse was recorded on a clay tablet discovered in 1948. The tablet described an eclipse that caused total darkness for over two minutes and said that the sun had been 'put to shame' when the new moon forced it to set during the daytime. As with many early interpretations of the solar eclipse, you can discern elements of anthropomorphism and the supernatural in this report.
Another solar eclipse that was associated with an important historical event occurred sometime in 763 B.C.E when the Assyrian Empire dominated a large part of the Mideast. The Assyrian Empire included what is now the country of Iraq, where a total solar eclipse darkened the skies for approximately five minutes. The records are not entirely clear on the timing, but a major insurrection occurred in the city of Ashur directly before or after the eclipse, linking the two events together in the collective mind of the empire.
King Henry I died in England not long after a solar eclipse that occurred on August 2, 1133. This unfortunate coincidence contributed greatly to the spread of the belief that solar eclipses were harbingers of death for rulers and ruling dynasties.
On May 29, 1919, British astronomer used a total solar eclipse to test Albert Einstein's Theory of General Relativity. By taking photographs of stars near the sun during the totality, Eddington was able to show that gravity could bend light, a phenomenon that is known as gravitational deflection and is a key part of Einstein's world changing theory.
In July 1878, people in the American West knew that a solar eclipse was coming. Laden with telescopes, protective glasses, and whatever other astronomical field gear they could get their hands on, amateur and professional scientists from all over the growing nation headed West for the thrills and education offered by the eclipse. One of these enthusiasts was an inventor named Thomas Edison, who used the solar eclipse to test his 'tasimeter,' which was designed to measure temperatures in the sun's corona. Although Edison's invention turned out to be a failure, many other scientific enterprises connected to the 1878 eclipse succeeded and the American passion for the solar eclipse was born.

The Cultural History of the Solar Eclipse

The solar eclipse has been a source of mystery, dread, and wonder for thousands of years. Documentation dating as far back as 2300 BCE includes references to the theological and supernatural beliefs that solar eclipses inspired in ancient peoples. Depending on the time, place, and culture, solar eclipses were conceived of as messages from angry gods, evidence of elemental warfare, and the impending demise or a ruling dynasty. Solar eclipses were also often associated with important historic events. This was before mathematics, astronomy, and the technology necessary for both became sophisticated enough to describe and predict them more accurately.

Because the sun has long been linked to fertility, growth, and life, solar eclipses were thought of as omens of mayhem, destruction, and death. Additionally, most ancient cultures had a sun god that occupied a critical place in their theology and pantheon. With all this in mind, it's easy to see why ancient peoples look toward the sky with terrible fear and trembling during the darkness brought on by a solar eclipse.

In order to understand the levels of reverence and fear with which ancient peoples viewed the reality of the solar eclipse, consider the legendary fate of the Greek philosopher Anaxagoras. A well respected Athenian thinker during the 5th Century BCE, Anaxagoras denied that solar eclipses had anything to do with the will of the gods and explained them, correctly, as the action of the moon casting its shadow upon the earth.

Outraged at such blasphemy, the enlightened citizens of Athens prosecuted Anaxagoras for impiety and he was eventually exiled from the city-state he loved for the rest of his life. Although many scholars have speculated that the fate of Anaxagoras was either politically motivated or a simple fabrication, the fact that the legend was ever believed is ample evidence of the importance the Athenians placed on the solar eclipse.

Whatever fate actually befell Anaxagoras, his scientific explanation of the solar eclipse apparently exerted a powerful influence on the Greek mind. As the Hellenic peoples continued to study the phenomenon of the solar eclipse from a scientific perspective, they began predicting them with no little success. But although this new predictability signaled a form of control, the myths and superstitions associated with solar eclipses endured for centuries.

By the 1970's, people in the United States had begun to consider the approach of a solar eclipse as a source of celebration, wonder, and unity. It was during this time that watching a solar eclipse became a group activity, a joyous occasion when friends and family gathered in fields wearing protective glasses and gasping in enthusiastic wonder as the skies began to darken.

In many ways, this evolution is emblematic of advances made in science more generally. The changing course of the solar eclipse's cultural interpretation runs parallel to humankind's intellectual journey from a superstitious worldview dominated by irrationality and fear to a more scientific and rational one.

Conclusion: Great American Total Solar Eclipse

Nowhere are the benefits of this evolved worldview more on display than in the American public's enthusiasm for the coming eclipse. People all over the country have circled August 21, 2017 on their calendars, with many of them already referring to this incredible astronomical event as "The Great American Total Solar Eclipse."

Solar Eclipse Explained: Definition, Diagram, and History

Needless to say, their excitement is justified. On August 21 , we will bear witness to the first total solar eclipse visible in the United States in almost 40 years. But it's not just the amount of time that's elapsed since the last total eclipse that makes this one so special. The 'path of totality,' which is the area in which the eclipse will be total, stretches from the northwest in Oregon all the way to southeast in South Carolina.

For everyone outside this huge area, the eclipse will be partial. But either way, the Great American Total Solar Eclipse will be an event that brings people from all over North America together to celebrate a moment of joy, camaraderie, and wonder.