3^rd Trumpet:  And the third angel sounded the blast of a trumpet; and there fell down from the air of the sky, a great and mighty star, as stretching across the sky of heaven, burning as set on fire, as if it were a lamp or torch and it fell down upon the third part of the streams and rivers and upon the fountains, that is, the supply of waters; And the name and character of the star is called Wormwood or a calamity of bitterness; and the third part of the rainy waters became wormwood or a calamity of bitterness; and an abundant and a great many human beings began to die off, because of the rainy waters, because they were made bitter. [Revelation 8:10-11].

Phase Three:  6^th Seal, 3^rd Trumpet, 3^rd Vial

[Rev. 6:13] And the stars of heaven fell unto the earth, even as a fig tree casteth her untimely figs, when she is shaken of a mighty wind.

[Rev. 8:10-11] And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters; And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter.

[Rev. 16:4] And the third angel poured out his vial upon the rivers and fountains of waters; and they became blood.

The “stars” and “a great star” and “Wormwood” is a comet, which will hit the earth’s atmosphere and melts completely before reaching the earth’s surface. Embedded within the frozen mass of gasses that form the comet’s nucleus, there are thousands, perhaps millions of tiny pieces of meteoric rock. These rocks will not melt like the frozen gases; instead, they will appear as “falling stars”“third” of the “rivers and upon the fountains of waters”among the continental land masses. that burn themselves out in the earth’s atmosphere. The entrance of the comet into the earth’s atmosphere will be heralded as a meteor storm and its final effect will be the poisoning of much of the earth’s water supply as the dense fog like gases descend upon the rivers and lakes within the continental land masses. It is most likely; this comet will fall upon the Eurasia continent, as it would fit the “third”of the “rivers and upon the fountains of waters” among the continental land masses.

Astronomers classify comets according to how long they take to orbit the sun. Short-period comets need less than 200 years to complete one orbit, while long-period comets take 200 years or longer.

Astronomers believe that comets are leftover debris from a collection of gas, ice, rocks, and dust that formed the outer planets about 4.6 billion years ago. Some scientists believe that comets originally brought to Earth some of the water and the carbon-based molecules that make up living things.

Parts of a comet:  The nucleus of a comet is a ball of ice and rocky dust particles that resembles a dirty snowball. The ice consists mainly of frozen water but may include other frozen substances, such as ammonia, carbon dioxide, carbon monoxide, and methane. Scientists believe the nucleus of some comets may be fragile because several comets have split apart for no apparent reason.

As a comet nears the inner solar system, heat from the sun vaporizes some of the ice on the surface of the nucleus, spewing gas and dust particles into space. This gas and dust forms the comet's coma. Radiation from the sun pushes dust particles away from the coma. These particles form a tail called the dust tail. At the same time, the solar wind -- that is, the flow of high-speed electrically charged particles from the sun-converts some of the comet's gases into ions (charged particles). These ions also stream away from the coma, forming an ion tail. Because comet tails are pushed by solar radiation and the solar wind, they always point away from the sun.

Most comets are thought to have a nucleus that measures about 10 miles (16 kilometers) or less across. Some comas can reach diameters of nearly 1 million miles (1.6 million kilometers). Some tails extend to distances of 100 million miles (160 million kilometers).

Comets lose ice and dust each time they return to the inner solar system, leaving behind trails of dusty debris. When Earth passes through one of these trails, the debris become meteors that burn up in the atmosphere. Eventually, some comets lose all their ices. They break up and dissipate into clouds of dust or turn into fragile, inactive objects similar to asteroids.

The long, oval-shaped orbits of comets can cross the almost circular orbits of the planets. As a result, comets sometimes collide with planets and their satellites. Many of the impact craters in the solar system were caused by collisions with comets.

Studying comets:  Scientists learned much about comets by studying Halley's Comet as it passed near Earth in 1986. Five spacecraft flew past the comet and gathered information about its appearance and chemical composition. Several probes flew close enough to study the nucleus, which is normally concealed by the comet's coma. The spacecraft found a roughly potato-shaped nucleus measuring about 9 miles (15 kilometers) long. The nucleus contains equal amounts of ice and dust. About 80 percent of the ice is water ice, and frozen carbon monoxide makes up another 15 percent. Much of the remainder is frozen carbon dioxide, methane, and ammonia. Scientists believe that other comets are chemically similar to Halley's Comet.

Another comet nucleus that has been seen by spacecraft cameras is that of Comet Borrelly. During a flyby in 2001, the Deep Space 1 spacecraft observed a nucleus about half the size of the nucleus of Halley's Comet. Borrelly's nucleus was also potato-shaped and had a dark black surface. Like Halley's Comet, Comet Borrelly only released gas from small areas where holes in the crust exposed the ice to sunlight.

In 1994, astronomers observed a comet named Shoemaker-Levy 9, which had split into more than two dozen pieces, crashing into the planet Jupiter. One of the most active comets seen in more than 400 years was Comet Hale-Bopp, which came within 122 million miles (197 million kilometers) of Earth in 1997. This was not an especially close approach for a comet. However, Hale-Bopp appeared bright to the unaided eye because its unusually large nucleus gave off a great deal of dust and gas. The nucleus was estimated to be about 18 to 25 miles (30 to 40 kilometers) across.

Contributor: Donald K. Yeomans, Ph.D., Senior Research Scientist, Jet Propulsion Laboratory.

How to cite this article:To cite this article, World Book recommends the following format: Yeomans, Donald K. "Comet." World Book Online Reference Center. 2005. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar125580.