A Dark Shadow Crosses the Earth
By “Awake!” correspondents in Australia
IT WAS May 28, 585 before the Common Era. The scene was a battlefield in Asia Minor. Lydians and Medes were locked in conflict. Suddenly, the sun grew dark. Awestruck by that spectacle, the combatants promptly ended their six-year war.
What caused that seemingly ominous darkness? It resulted from an eclipse of the sun.
Our 1976 Eclipse
Though many persons of centuries past were struck with terror when an eclipse made the sun grow dark, millions looked forward to viewing a total solar eclipse predicted for October 23, 1976. The path of totality, a strip about 160 kilometers (100 miles) wide, began near Lake Victoria in Central Africa and swept across the Indian Ocean, encountering land again at the southeastern tip of Australia. It passed over the state of Victoria, including its capital city of Melbourne, where the populace was treated to a view of a total eclipse of the sun for the first time in more than 140 years. After crossing the southern coast of New South Wales, the spectacle petered out in the Pacific.
Many professional and amateur astronomers were among those who experienced this celestial event about 4:30 p.m., Saturday, October 23, 1976. The total phase of the spectacle lasted about three minutes. It is estimated that two million residents of Victoria viewed the eclipse on television.
Directly in the path of the eclipse were three locations being used by Jehovah’s Witnesses for Christian assemblies. Since the eclipse took place during the afternoon sessions, few conventioners witnessed it personally. Like most persons in Australia, they viewed it with interest on television later that day.
Perhaps you have seen a total eclipse of the sun. If so, do you know what causes this spectacle? Maybe you have heard that there is danger in viewing it directly. Is that true? Also, do such eclipses result in any benefits?
A Grand Spectacle
In simple terms, a solar eclipse occurs when the moon moves into a position directly between the sun and the earth. If the sun is not entirely hidden by the moon, the eclipse is partial. A total solar eclipse occurs when the sun is entirely hidden by the moon. A partial eclipse of the sun may occur in various places on earth up to five times each year. But a total solar eclipse occurs rarely at any one point on earth.
Two shadows are produced by the moon in the course of total solar eclipse. One, called the umbra, is the total shadow and is shaped like a pointed cone. The point, or vertex, is at the earth’s surface and the base of the cone is the moon’s circumference. The lesser or half shadow, called the penumbra, runs in the opposite direction. Its small end is toward the moon. The penumbra widens out in an area much greater than the umbra on each side of it. In this area, observers see a partial eclipse, as the moon overlaps the sun only to varying degrees.
What makes a total eclipse of the sun so fascinating? Well, very little happens for the first one and a quarter hours, while the shadow of the moon slowly moves across the face of the sun, which gradually takes on the shape of a crescent. As the crescent grows very thin, however, dusk begins to fall. Then, suddenly, the sun disappears! The bright-blue sky “vanishes,” the temperature drops, darkness descends, the stars appear and the total phase of the eclipse begins. Once again, the moon has blotted out the sun!
Next the corona, the sun’s gaseous outer envelope, can be seen as a beautiful white halo about twice the size of the sun and surrounding the dark disk of the moon. Truly an unforgettable sight! For a few seconds at the beginning and end of the total phase, there appears to be a string of tiny beads around the sun. This phenomenon is caused by light shining through the valleys of the moon. The gleaming points of light are known as Baily’s Beads and were named for the English astronomer Francis Baily, who recorded their appearance during an eclipse in 1836. While the brilliance of the day sky is decreased enormously, the general appearance of the landscape is similar to that under a full moon. It is not completely dark.
At about the moment of totality, when the moon covers the bright face or photosphere of the sun, there flashes into view for just a few seconds and as an arc around the dark moon, the rosy-red chromosphere or color sphere of the sun. This is known as the “flash spectrum” and is due to a rarefied envelope of luminous gas lying immediately above the bright surface of the sun. A second flash occurs at the end of totality. Just before and after totality, when a thin crescent of the sun is visible, bands of light and shade appear on the ground and on the walls of buildings. They ripple like waves, moving along perpendicular to their length.
Suddenly, the sun appears again as a thin crescent! Daylight returns as dawn. The crescent of the sun gradually widens until, one and a quarter hours later, the moon leaves the sun’s disk. Full daylight thus returns.
So awesome is the solar eclipse that some primitive people believe it to be a fainting, or even sickness and death, of the sun. Certain Eskimos and the inhabitants of the Aleutian Islands have believed that during this event the sun and the moon move out of their normal positions to get a better view of affairs on the earth. In Tahiti solar eclipses have been explained as a mating of the sun and the moon, which supposedly produces the stars!
In the realm of reality, this temporary obscuring of the sun also disturbs birds and animals. During the semidarkness of the eclipse, bees stop buzzing, birds cease twittering, chickens have been known to go to roost and cattle have settled down in fields as they would at sunset. They ‘bed down’ for what turns out to be perhaps a three-minute “night.”
Safely Viewing a Solar Eclipse
For several weeks prior to the solar eclipse of October 23, 1976, in southeastern Australia, the news media repeatedly warned people not to look at this spectacle directly. All living along the eclipse path were encouraged to stay indoors and watch it on television instead of risking permanent eye damage either by looking at or photographing the eclipse itself. Special committees were set up to advise all concerned of the dangers involved in watching this celestial event.
During totality (the minutes when the sun is completely blotted out), there is less likelihood of eye damage. But during the half hour prior to or after totality irreparable eye damage would result if a person viewed the eclipse directly or photographed it without a special protective lens.
Knowledge Gained from Solar Eclipses
Many interesting facts have been gleaned from solar eclipses. For instance, consider the corona or crown of the sun. During a total eclipse it is seen as a frosty haze of light wisping out from the now dark disk of the sun. Truly a beautiful sight against the background of the deep-blue sky! By measuring the polarization of the particles in the inner and outer areas of the corona, scientists can determine where the atmosphere of the sun ends and the light refracted particles of outer space begin.
The rose-colored prominences or immense flames of incandescent gases extending out from the sun for thousands of miles have yielded other information. These flaming prominences impress one with the sun’s beneficial role—that of a burning fire sending out its radiant heat into the cold space around it. From examining these solar flames the previously unknown chemical element helium was first discovered in 1868.
The precise alignment of the sun, the moon and the earth at the time of total solar eclipse also makes it possible to arrive at exact measurements of the earth’s surface within the general zone covered by an eclipse. A check on the accepted measurements then is made. The use of this information is impaired, however, because of the infrequency and diverse locations of total solar eclipses.
The longest total eclipse of the sun in modern times occurred in the Philippines on June 20, 1955. It lasted for 7 minutes and 7.7 seconds. But this was a short time compared with three hours of darkness that fell over Jerusalem from about noon until 3 p.m. on the day of the death of Jesus Christ, Friday, April 1, 33 C.E. Luke’s gospel account indicates that darkness fell “because the sunlight failed.” (Luke 23:44-46) This could not have been due to a mere solar eclipse, however, since it happened at Passover time, when the moon is full. Solar eclipses can take place only at the time of the new moon. This unique and unusual event associated with Jesus’ death aptly demonstrates Jehovah God’s power over the sunlight.
To God also goes the credit for the awesome spectacle of the solar eclipse. He is the One who created the sun, the moon and the stars, “the heaven and the things in it.” (Rev. 10:6) Jehovah is also responsible for the laws by which heavenly bodies operate. Many persons are reminded of that when they consider the awesome solar eclipse that casts a dark shadow across the earth.
[Picture on page 18]
Stages of the eclipse