All about Solar Eclipses

Perry McCarney's image for:
"All about Solar Eclipses"
Image by: 

Since the dawn of civilization and long before, night falling in the middle of the day, darkness seeming to eat the sun, has induced terror. People like a certain amount of stability in their day to day lives, we always have, and nothing is more profound than our expectation of when it is meant to be light and when it is meant to be dark. It is only the advances we have made in science, and the increased knowledge we have gained through such endeavors, that has turned terror into pleasure for most people in the world today. Our ability to predict solar eclipses leading to many traveling to the geographical locations on the Earth's surface that will fall under the shadow of the moon. Enabling people to witness for themselves this fascinating celestial event.

An eclipse in astronomical terms is when one spatial body moves between two others, occluding (blocking) the light, whether produced or reflected, from one reaching the other. A solar eclipse, as seen from the surface of the Earth, is when our moon in its orbit moves between the sun, Sol, and the Earth, so that it casts its shadow upon the Earth's surface. From the point of view of an appropriately placed person, wearing suitable light-filtering eye protection, an arc of darkness grows in from the edge of the sun's orb until the sun appears to have a dark center with just a rim of light. The reduction in the sunlight reaching that location on the Earth's surface makes it seem as though night has fallen during what is normally the daylight portion of our 24 hour day. For the duration of the solar eclipse it is even possible to see some of the stars we can usually only see at night.

The sun is an enormous nuclear fusion reactor that burns continuously, at least from our time-scale perspective. So the moon is always casting a shadow directly behind it. As does the Earth and every other orbiting body in our solar system, from the smallest particle of dust to the largest planet, Jupiter. Even comets do, but this is generally hidden by the tail of gases erupting from the comet's heated surface.

The moon orbits the Earth once every lunar month, approximately 28 days. This might make us wonder why we don't experience a solar eclipse, at least somewhere, once a month. The reason we do not is because the moon orbits the Earth's equator and the Earth is tilted, which is what produces the opposite seasons experienced in the northern and southern hemispheres. So most of the time, the moon's shadow misses the Earth's surface and no solar eclipse occurs. Through astronomical observation and computer modeling, scientists can predict when the moon's shadow will actually play across the Earth's surface instead of missing it, and where exactly that will occur.

Solar eclipses have held prominent positions in the myths, legends and even religions of all of the great civilizations of the past. Because of the progress of the moon across the face of the sun, many legends depicted solar eclipses as some monster devouring the sun; from the Chinese celestial dragon to the Egyptian snake, Apep. Solar eclipses have changed history, in China such events were deemed to foretell the future of the Emperor; a solar eclipse in 585 BC is accredited with ending a war between the Lydians and the Medes in Asia Minor, what is now Turkey.

While the solar astronomers of some of the greatest past civilizations developed the knowledge to predict solar eclipses, the dissemination of that knowledge was very restricted in those days. Terror was the primary response of the general populace to a solar eclipse. How much better to have the understanding to be able to enjoy such a fantastic show in our skies and some of the more exotic traditional efforts still carried out in some parts of the world to drive off the dragon eating the sun!

More about this author: Perry McCarney

From Around the Web