A total solar eclipse requires the umbra of the Moon’s shadow to touch the surface of the Earth. Because of the relative sizes of the Moon and Sun and their relative distances from Earth, the path of totality is usually very narrow (up to 270 kilometers across).
The following figure illustrates the path of totality produced by the umbra of the Moon’s shadow.
If you are in the path of totality the eclipse begins with a partial phase in which the Moon gradually covers more and more of the Sun. This typically lasts for about an hour until the Moon completely covers the Sun and the total eclipse begins. The duration of totality can be as short as a few seconds, or as long as about 8 minutes, depending on the details.
As totality approaches the sky becomes dark and a twilight that can only be described as eerie begins to descend. Just before totality waves of shadow rushing rapidly from horizon to horizon may be visible. In the final instants before totality light shining through valleys in the Moon’s surface gives the impression of beads on the periphery of the Moon (a phenomenon called Bailey’s Beads).
The last flash of light from the surface of the Sun as it disappears from view behind the Moon gives the appearance of a diamond ring and is called, appropriately, the diamond ring effect (image at right).
As totality begins , the solar corona (extended outer atmosphere of the Sun) blazes into view. The corona is a million times fainter than the surface of the Sun; thus only when the eclipse is total can it be seen; if even a tiny fraction of the solar surface is still visible it drowns out the light of the corona. At this point the sky is sufficiently dark that planets and brighter stars are visible, and if the Sun is active one can typically see solar prominences and flares around the limb of the Moon, even without a telescope (see image at left).
The Sun The sun is the largest object in the solar system. It is a middle-sized star and there are many other stars out in the universe just like it. Even though it is only a middle-sized star it is large enough to hold over 1 million Earth's inside if it were hollow. The temperature on the sun is far too much for any living thing to bear. On the surface it is 10, 000 degrees Fahrenheit and the ...
The period of totality ends when the motion of the Moon begins to uncover the surface of the Sun, and the eclipse proceeds through partial phases for approximately an hour until the Sun is once again completely uncovered. A partial solar eclipse is interesting; a total solar eclipse is awe-inspiring in the literal meaning of the phrase. If you have an opportunity to observe a total solar eclipse, don’t miss it! It is an experience that you will never forget.
(click to see more photos)
Solar Eclipses for Beginners
(c) Copyright 2009 by Fred Espenak
What is an eclipse of the Sun? What causes eclipses and why? How often do eclipses happen and when is the next eclipse of the Sun? You’ll learn the answers to these questions and more in MrEclipse’s primer on solar eclipses. Before we learn more about the eclipses of the Sun, we need to first talk about the Moon.
Phases of the Moon.
Phases of The Moon
The Moon is a cold, rocky body about 2,160 miles (3,476 km) in diameter. It has no light of its own but shines by sunlight reflected from its surface. The Moon orbits Earth about once every 29 and a half days. As it circles our planet, the changing position of the Moon with respect to the Sun causes our natural satellite to cycle through a series of phases:
* New Moon > New Crescent > First Quarter > Waxing Gibbous > Full Moon >
Waning Gibbous > Last Quarter > Old Crescent > New Moon (again)
The phase known as New Moon can not actually be seen because the illuminated side of the Moon is then pointed away from Earth. The rest of the phases are familiar to all of us as the Moon cycles through them month after month. Did you realize that the word month is derived from the Moon’s 29.5 day period?
... a solar eclipse). A solar eclipse occurs when the Moon, revolving in its orbit around the Earth, moves across the disk of the Sun so that the shadow ... of the Moon ...
To many early civilizations, the Moon’s monthly cycle was an important tool for measuring the passage of time. In fact many calendars are synchronized to the phases of the Moon. The Hebrew, Muslem and Chinese calendars are all lunar calendars. The New Moon phase is uniquely recognized as the beginning of each calendar month just as it is the beginning on the Moon’s monthly cycle. When the Moon is New, it rises and sets with the Sun because it lies very close to the Sun in the sky. Although we cannot see the Moon during New Moon phase, it has a very special significance with regard to eclipses.
Geometry of the Sun, Earth and Moon During an Eclipse of the Sun
The Moon’s two shadows are the penumbra and the umbra.
(Sizes and distances not to scale)
The Moon’s Two Shadows
An eclipse of the Sun (or solar eclipse) can only occur at New Moon when the Moon passes between Earth and Sun. If the Moon’s shadow happens to fall upon Earth’s surface at that time, we see some portion of the Sun’s disk covered or ‘eclipsed’ by the Moon. Since New Moon occurs every 29 1/2 days, you might think that we should have a solar eclipse about once a month. Unfortunately, this doesn’t happen because the Moon’s orbit around Earth is tilted 5 degrees to Earth’s orbit around the Sun. As a result, the Moon’s shadow usually misses Earth as it passes above or below our planet at New Moon. At least twice a year, the geometry lines up just right so that some part of the Moon’s shadow falls on Earth’s surface and an eclipse of the Sun is seen from that region.
The Moon’s shadow actually has two parts:
* The Moon’s faint outer shadow.
* Partial solar eclipses are visible from within the penumbral shadow.
* The Moon’s dark inner shadow.
* Total solar eclipses are visible from within the umbral shadow.
When the Moon’s penumbral shadow strikes Earth, we see a partial eclipse of the Sun from that region. Partial eclipses are dangerous to look at because the un-eclipsed part of the Sun is still very bright. You must use special filters or a home-made pinhole projector to safely watch a partial eclipse of the Sun (see: Observing Solar Eclipses Safely).
What is the difference between a solar eclipse and a lunar eclipse? A lunar eclipse is an eclipse of the Moon rather than the Sun. It happens when the Moon passes through Earth’s shadow. This is only possible when the Moon is in the Full Moon phase. For more information, see Lunar Eclipses for Beginners.
Our Sun continuously converts hydrogen into helium and with this process it provides the essentials for life processes. In doing this it controls "our climate, provides light, raises tides, and drives the food chain" (Schaefer 34). Our Sun also has influenced many beliefs now and in the past. History has documented Sun worshipping religions while many current societies use solar calendars ( ...
Total Solar Eclipse and Path of Totality
Total Solar Eclipses and the Path of Totality
If the Moon’s inner or umbral shadow sweeps across Earth’s surface, then a total eclipse of the Sun is seen. The track of the Moon’s umbral shadow across Earth is called the Path of Totality. It is typically 10,000 miles long but only about 100 miles wide. It covers less than 1% of Earth’s entire surface area. In order to see the Sun become completely eclipsed by the Moon, you must be somewhere inside the narrow path of totality.
The path of a total eclipse can cross any part of Earth. Even the North and South Poles get a total eclipse sooner or later. Just one total eclipse occurs each year or two. Since each total eclipse is only visible from a very narrow track, it is rare to see one from any single location. You’d have to wait an average of 375 years to see two total eclipses from one place. Of course, the interval between seeing two eclipses from one particular place can be shorter or longer. For instance, the last total eclipse visible from Princeton, NJ was in 1478 and the next is in 2079. That’s an interval of 601 years. However, the following total eclipse from Princeton is in 2144, after a period of only 65 years.
2006 Total Solar Eclipse
A composite image reveals subtle structure in the Sun’s corona.
(click to see more photos)
The total phase of a solar eclipse is very brief. It rarely lasts more than several minutes. Nevertheless, it is considered to be one of the most awe inspiring spectacles in all of nature. The sky takes on an eerie twilight as the Sun’s bright face is replaced by the black disk of the Moon. Surrounding the Moon is a beautiful gossemer halo. This is the Sun’s spectacular solar corona, a super heated plasma two million degrees in temperature. The corona can only be seen during the few brief minutes of totality. To witness such an event is a singularly memorable experience which cannot be conveyed adequately through words or photographs. Nevertheless, you can read more about the Experience of Totality in the first chapter of Totality – Eclipses of the Sun.
anyone lived in a pretty how town by e. e. cummings 'anyone lived in a pretty how town' is about how commonplace language and commonplace lives can be intimate and profound. It is a technically innovative poem which designed so that the reader cannot know what is going on from a 'distant', perfunctory viewpoint. Repetition, strange grammatical usages, and impersonal nouns demand very close reading ...
Scientists welcome the total eclipse as a rare opportunity to study the Sun’s faint corona. Why is the corona so hot? What causes it to spew massive bubbles of plasma into space through coronal mass ejections? Can solar flares be predicted and what causes them? These major mysteries may eventually be solved through experiments performed at future total eclipses.
For amateur astronomers and eclipse chasers, an eclipse of the Sun presents a tempting target to photograph. Fortunately, Solar Eclipse Photography is easy provided that you have the right equipment and use it correctly. See MrEclipse’s Picks for camera, lens and tripod recommendations. For more photographs taken during previous lunar eclipses, be sure to visit Solar Eclipse Photo Gallery. It’s also possible to capture a solar eclipse using a video camcorder.
The most recent total solar eclipse occurred on March 29, 2006 and was visible from Africa and central Asia. Fred Espenak led a Spears Travel tour to Libya to witness the event. You can see a collection of his photographs at 2006 Eclipse Gallary. Reports (with photos) from some of his earlier eclipse expeditions include 2001 Eclipse in Zambia, 1999 Eclipse in Turkey, 1998 Eclipse in Aruba and 1995 Eclipse in India.
The next two total eclipse of the Sun are both visible from China: 2008 and 2009. Join Fred Espenak on a Spears Travel tour to witness one (or both!) of these spectacular events.
Annular Solar Eclipse and the Path of Annularity
Annular Solar Eclipses
Unfortunately, not every eclipse of the Sun is a total eclipse. Sometimes, the Moon is too small to cover the entire Sun’s disk. To understand why, we need to talk about the Moon’s orbit around Earth. That orbit is not perfectly round but is oval or elliptical in shape. As the Moon orbits our planet, it’s distance varies from about 221,000 to 252,000 miles. This 13% variation in the Moon’s distance makes the Moon’s apparent size in our sky vary by the same amount. When the Moon is on the near side of its orbit, the Moon appears larger than the Sun. If an eclipse occurs at that time, it will be a total eclipse. However, if an eclipse occurs while the Moon is on the far side of its orbit, the Moon appears smaller than the Sun and can’t completely cover it. Looking down from space, we would see that the Moon’s umbral shadow is not long enough to reach Earth. Instead, the antumbra shadow reaches Earth.
Both Sun and Moon play significant roles in this old poem, in a symbolic and supernatural way, in order to reinforce the mood that Samuel Taylor Coleridge has attempted to create in his use of old legends and superstitions. The role that the sun and moon play in this tale of cursed sailors is an old one, retold over and over the years that Coleridge adapted for his own. Although mentioned several ...
The track of the antumbra is called the path of annularity. If you are within this path, you will see an eclipse where a ring or annulus of bright sunlight surrounds the Moon at the maximum phase. Annular eclipses are also dangerous to look directly with the naked eye. You must use the same precautions needed for safely viewing a partial eclipse of the Sun (see: Observing Solar Eclipses Safely).
Annularity can last as long as a dozen minutes, but is more typically about half that length. Since the annular phase is so bright, the Sun’s gorgeous corona remains hidden from view. But annular eclipses are still quite interesting to watch. You can read reports about the annular eclipses of 1999 in Australia and 2003 in Iceland. More recently, visit the 2005 Annular Solar Eclipse Photo Gallery.
2005 Annular Solar Eclipse
This sequence shows the eclipse just before, during and after annularity.
(click to see more photos)
The “Oddball” Hybrid Eclipse
There’s one more type of solar eclipse to mention and its a real oddball. Under rare circumstances, a total eclipse can change to an annular eclipse or vice versa along different sections of the eclipse path. This happens when the curvature of Earth brings different points of the path into the umbral (total) and antumbral (annular) shadows, respectively. Hybrid eclipses are sometimes called annular/total eclipses. The last hybrid eclipse was in 2005 and the next one is in 2013.
Solar Eclipse Frequency and Future Eclipses
During the five thousand year period 2000 BCE to 3000 CE, planet Earth experiences 11,898 solar eclipses as follows:
Effects During a Total Solar Eclipse
A total solar eclipse begins almost unnoticeably. As the Moon starts its passage across the face of the Sun, a small “bite” appears on the western edge of the Sun. Gradually, as more and more of the Sun disappears, an interesting effect can be seen: the tiny spots of light shining through the leaves of a tree, for example, show up on the ground as crescent images of the slowly vanishing Sun.
It was a magnificent night. The stars where glittering over us. We even saw a falling star. The moon was bright and full. For us it was the first time that we walked together under the full moon by the sea shore. The moon was shining all over the sea. Sometimes you could hear a tiny splash because there was a small spot where the fishes were jumping after each other just like a freshly married ...
As the partial phase progresses for about an hour, there is little hint of the approaching darkness. But in the last few minutes before totality, daylight fades very quickly.
While a small crescent of the sun remains in the sky, a curious eclipse phenomenon is often observed. Thin wavy lines of alternating light and dark can be seen moving and undulating in parallel on plain light-colored surfaces. These so-called shadow bands are the result of sunlight being distorted by irregularities in the Earth’s atmosphere, and are best observed on an open floor or wall.
As the narrow crescent of the Sun finally begins to disappear, tiny specks of light remain visible for a few seconds more. These points of light are spaced irregularly around the disappearing edge of the Sun, forming the appearance of a string of beads around the dark disk of the Moon. These lights are known as Baily’s beads, named after Francis Baily, the 18th century English amateur astronomer who was the first to draw attention to them. The beads are actually the last few rays of sunlight shining through valleys on the edge of the Moon. Baily’s beads make their brief appearance up to 15 seconds before totality. When a single point of sunlight remains, a beautiful “diamond ring” effect is created against the outline of the Moon. This final sparkling instant signals the arrival of the moon’s shadow. The last ray of sunlight vanishes and totality begins.
Suddenly the sky above is dark. The Moon’s shadow, racing along the Earth at speeds up to several thousand miles per hour, brings a swift and dramatic nighttime effect. The sky near the horizon still appears bright, and this distant scattered light produces a slight reddish glow and unusual shadow effects. This daytime darkness is not quite as black as at night. But its startling onset and unearthly appearance combine to create a unique visual ambience.
In the center of this darkened sky hangs the featured spectacle of the eclipse — the corona of the Sun. This pearly white crown of light shines in all directions around the darkened solar disk. A million times fainter than the Sun itself, the full glory of the corona is visible only during a total solar eclipse. Wispy plumes and streamers of coronal light reach out distances up to several diameters of the Sun before they fade into darkness.
Against the backdrop of the white corona and the black disk of the Moon, two colorful effects are usually seen. First is the light from the Sun’s lower atmosphere, the chromosphere. For a few seconds both after the beginning and before the end of totality, this pinkish glow appears at the edge of the Moon. Also often visible are several solar prominences. These red cloudlike appendages arch above the surface, reach a maximum height of nearly one-third the diameter of the Sun itself.
This marvelous view of the Sun clearly commands the center of attention during totality. But there are other sights to see as well. Because the direct light of the Sun is blocked, some of the brighter stars and planets become visible. Sometimes a total solar eclipse reveals a small comet on its path near the Sun.
The darkness of totality resembles nighttime, and plants and animals react accordingly. Birds stop singing and may go to roost. Daytime flower blossoms begin to close as if for the night. Bees become disoriented and stop flying. The temperature drops in the coolness of the Moon’s shadow. All of Nature seems still and quiet for this brief moment of daytime darkness.
And then the shadow passes. A bright speck of sunlight flashes into view at the western edge of the Sun as the corona disappears. Totality has ended. The same events that preceded totality now occur in reverse order and on the opposite side of the Sun. Baily’s beads appear, followed by a thin crescent of the Sun. Daylight returns as more and more of the Sun is gradually uncovered by the passing Moon.
Finally the complete disk of the Sun is restored. The eclipse is over. The Moon continues in its orbit around the Earth, casting its shadow off into the vastness of space. Nothing tangible remains of the eclipse except some photographs and scientific data. Yet the memory of the experience is permanent — the fleeting beauty of the corona etched into the mind’s eye by the sheer grandeur of the event. There is simply nothing else like it.