Solar Eclipses


An eclipse occurs when one celestial body, such as the moon or a planet, moves into the shadow of another celestial body. On Earth, we have two types of eclipses: the eclipse of the moon called a lunar eclipse and the eclipse of the sun called a solar eclipse.

In the case of a solar eclipse, the moon moves between the Earth and the sun, blocking the intensity of the light. The results are that while we can’t see the full light of the sun, the damaging radiation is still getting through.

With protected lenses, a solar eclipse allows scientists and viewers to see areas of the sun that would normally not be available. A solar eclipse also lets the moon cast a shadow on the Earth, making it look like dusk to dark.

Full Solar eclipse

Solar eclipses happen about every 18 months, but unlike lunar eclipses, the solar eclipse only lasts for a few minutes.

Achieving a complete or total eclipse is a combination of a number of very exacting circumstances that involve both size and distance.

On Earth we are incredibly lucky because the distance between the Earth and the moon, combined with the size of the moon allows us to have a perfect total eclipse. This wouldn’t happen if the moon was smaller or larger or even at a farther or closer distance.

Types of Solar Eclipses:

When the moon’s orbit exactly matches that of the Earth and the sun it moves in between and causes a solar eclipse. There are three distinct types of solar eclipses:

Total solar eclipse: this type of eclipse is only visible in small locations on the Earth. It requires that you be in the exact center of the eclipse so that the moon is balanced between the sun and the Earth.

Many of these eclipses happen all over the globe but are often at sea or in areas not inhabited by people. During a total eclipse the moon’s shadow causes the sky to get very dark, almost as if it were nighttime.

A total eclipse requires that the sun, moon, and the Earth be in a direct line.

As we continue to explore our solar system we are finding that we may have the only perfect balance of sun, moon, and planet to observe complete or total lunar and solar eclipses.

Unless there is a perfect alignment of size and distance of the sun, Earth, and moon, there are only partial eclipses. The distance between the sun and the Earth is nearing 400 times the distance of the sun and the moon.

The “balance” of this condition happens when you realize that the sun’s diameter just happens to be almost 400 times larger than the moon’s diameter.

So far, we don’t know of any other planet, moon, sun ratio in our solar system that matches the one that we have.

Partial solar eclipse: This form of eclipse occurs when the Earth, moon, and the sun aren’t exactly lined up. The sun will appear to have a dark shadow on only part of its surface.

Annular (ANN you ler) solar eclipse: This type of eclipse happens when the moon is the farthest distance from the Earth and doesn’t block out the entire sun.

Partial Solar eclipse

The moon appears to be smaller, and it looks like a dark disk on top of the sun’s larger disk. An annular solar eclipse makes it look like the moon has a ring around it.

Solar eclipse shadows:

When a solar eclipse happens the moon actually casts two shadows on the Earth. One shadow is called the umbra, and it gets smaller as it reaches the Earth.

It’s the dark center of the shadow of the moon. If you are standing in the umbra you would see a total eclipse. The second shadow is called penumbra, and it gets larger as it reaches the Earth. If you are standing in the penumbra you would see a partial eclipse.

History of the Name:

Humans have been observing solar eclipses throughout history. Early civilizations thought that a solar eclipse was a signal for doom or that their gods were angry at them and punishing them.

They were often thought of as “omens” of destruction or death, and they looked to their religious leaders to try to get answers. The word “eclipse” comes from  ekleipsis, the ancient Greek word for being abandoned.

Dangers of solar eclipses:

Even though the Moon is covering the Sun, it doesn’t stop the incredibly damaging rays of the Sun. Never look directly at a solar eclipse as it can severely damage your eyes.

If you intend on attending a solar eclipse get specially designed eclipse glasses. You should also never try to view an eclipse through a camera that doesn’t have a specially designed lens.

Interesting Information:

Ancient Greeks were known for recording many of their events, including solar eclipses. The poet Archilochus wrote of the April 6, 647 BCE total solar eclipse: There is nothing beyond hope, nothing that can be sworn impossible, nothing wonderful, since Zeus, father of the Olympians, made night from mid-day, hiding the light of the shining Sun, and sore fear came upon men.”

John Milton, the British poet is well-known for so many of his writings. In his poem “Paradise Lost,” Milton includes: “As when the Sun, new risen, Looks through the horizontal misty air, Shorn of his beams, or from behind the Moon, In dim eclipse, disastrous twilight sheds On half the nations and with fear of change Perplexes monarchs.”

Animals are also affected by a total solar eclipse. Many animals become unsettled and confused, but since the eclipse only lasts a few minutes, their upset doesn’t last long.

Important Events:

Today we can predict solar eclipses all over the world for many years in advance. This has led to the ability to announce gatherings for solar eclipse fans and make arrangements for adults, kids, and scientists to share in the experience. Many locations around the globe prepare in advance when a total solar eclipse is in their area.

Albert Einstein’s theory of general relativity remained as an idea until May 29, 1919. At that time, Sir Arthur Eddington, a British astronomer and mathematician, used the total solar eclipse to test Einstein’s theory.

Eddington took pictures of the stars that were located close to the sun during the totality and was able to demonstrate that gravity can indeed bend light. It proved Einstein’s theory to be correct in a phenomenon called gravitational deflection.

Eclipse shadow

It was due to a solar eclipse that the French astronomer Jules Janssen discovered helium. Helium is the second lightest and the second most abundant element that we know of.

Janssen used the August 18, 1868 solar eclipse to prove its existence. Because the solar eclipse was responsible for the discovery they named helium after the Greek word for sun: Helios.

Archeologists have found records dating back as far as 2500 BCE from both the ancient Chinese and the Babylonians that indicate that they were sophisticated in the study of the skies to be able to predict solar eclipse.

The ancient Chinese thought that solar eclipses were signs of success and health for their emperor. Failing to predict a solar eclipse would mean that the emperor’s life might be in danger.

The oldest solar eclipse in recorded human history is listed at October 22, 2134 BCE.

In one of the records of the ancient Chinese, they describe a solar eclipse as “the sun has been eaten.”

Their tradition was to bang pots and drums to make as much loud noise as possible to frighten the dragon away that had eaten the sun.

Ancient Babylonian clay tablets that have been found indicate that the Babylonians recorded and predicted eclipses.

The earliest mention of an eclipse on the clay tablets is May 3, 1375 BCE. The Babylonians were the first people to make use of the “saros cycle” for their solar eclipse predictions.

The saros cycle relates to the cycle of the moon and is about 6,585.3 days or 18 years, 11 days, and 8 hours long. Just like the ancient Chinese, the Babylonians thought that solar eclipses were bad news for their rulers and kings.

When a solar eclipse was predicted, the ancient Babylonians would choose a temporary king to last during the time of the eclipse, hoping that it would be this individual that would face their god’s anger instead of the true king.

Herodotus was an ancient Greek historian. In his records he indicated that the solar eclipse of 585 BCE stopped a pending war between the Medes and the Lydians. When they saw the skies darken they made peace with each other.

The Greek astronomer Hipparchus made use of a solar eclipse to figure out that the moon was around 268,000 mi/429,000 km distance from the Earth. His math was pretty good because it’s only about 11% more than the numbers used by scientists today.

Ptolemy was a famous Greek astronomer (ca 150 CE). He kept records of his eclipse observations and demonstrated a very sophisticated way of predicting both solar and lunar eclipses.

An example of this is in his knowledge of the moon’s orbit details including its nodal points. His knowledge of the nodal points led him to figure that up to two solar eclipses would happen within seven months in the same part of the world.

Throughout the ages eclipse pioneers tried to explain what a solar eclipse was. These pioneers included Chinese astronomer Liu Hsiang, Greek philosopher Plutarch, and Byzantine historian Leo Diaconus.

However, it wasn’t until Johannes Kepler gave the complete scientific description of a total solar eclipse in 1605 that science had an explanation.

Edmund Halley is known for the famous Halley’s Comet, but he also predicted both the path and timing of the May 3, 1715 total solar eclipse. Using mathematical calculations, he was only about 4 min and 18 mi/30 km off from the actual path and timing of the eclipse.

Archeoastronomer (and archeologist and an astronomer), Paul Griffin, made an incredible discovery during his 1999 investigation of the Loughcrew Cairn L Megalithic Monument in Ireland.

He found a set of petroglyphs in a spiral shape that corresponded to a solar eclipse that happened on Nov. 30, 3340 BCE. The symbols appeared consistent in a code showing the sun, moon, and the horizon, as well as 92 tracks of total solar eclipses, only the one for the 3340 BCE was visible at the site that displayed the geometric relationships.

Solar Eclipse Facts for Kids:

  • Solar eclipses happen all over the Earth at a rate of about two to five per year.
  • A “Totality” is a solar eclipse condition where the moon completely covers the view of the sun, allowing only the “corona” to be seen.
  • Somewhere on Earth there is a total eclipse happening about every 18 months. The reason that people don’t see them all is that they often happen in the middle of the oceans or in areas that humans can’t get to.
  • A “hybrid eclipse” is a rare form of eclipse and is dependent on the location that you view it from on Earth. The hybrid eclipse shifts between an annular and total eclipse.
  • Solar eclipses don’t last as long as lunar eclipses. A solar eclipse can last from 30 second all the way to 7 minutes, depending upon the viewing location.
  • The timing of a solar eclipse depends on the speed of the moon as it passes across the sun. The moon travels at 1,398 mph.
  • Viewing a solar eclipse from the North or South Poles can be quite a letdown because you will only ever see a partial eclipse.
  • The Path of Totality is the path of a total eclipse as the shadow passes over the Earth. A Path of Totality has a maximum width of 269 km.
  • An unusual situation occurs when almost identical eclipses occur after 18 yrs, 11 days. This is called a “Saros Cycle.”