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The Discovery story of Comet Seki-Lines

Part Six: A close call

    On the early morning of February 6, the observatory in Copenhagen received an international astronomical telegram. The Central Bureau for Astronomical Telegrams was located at this observatory to which many reports of new discoveries and unexpected events were sent. The telegram they received that morning came all the way from Japan. The name of the object was Comet Seki and the news was immediately sent to observatories all over the world. However, another telegram arrived soon after. It reported the discovery of a new comet found in Arizona. Needless to say, this was Comet Lines. The Central Bureau determined that the two comets were identical and renamed it Comet Seki-Lines. Although Mr. Lines found the comet first, his oversight caused a delay in confirmation by Lowell Observatory. The official date and time of his discovery, 22.00 local time on February 5, 1962, was the time Lowell Observatory confirmed the comet. It was 17 hours behind my discovery. There was apparently some controversy about this later, but he was definitely disadvantaged because there was nothing to prove that his discovery was made on February 4. The discovery of an astronomical object becomes effective only when it is accompanied by the positional measurements.

    The recognition of the discovery of this comet by a Japanese observer owes very much to the efforts of Mr. Honda and the speedy handling of the discovery report by Tokyo Astronomical Observatory. If there had been a one-day delay in confirmation of the object, the comet would have been named Comet Lines-Seki. It was indeed a close call.

    In spite of the freezing conditions and being late at night, Mr. Honda committed himself to confirming the object and reporting it to Tokyo Observatory. Throughout my life I can never forget his selfless dedication. It was about 10 years ago when I met Mr. Honda on the shore of a beautiful lake on one summer day.

    Comet Seki-Lines, which was found both in Arizona and Japan, moved west for some time as if hugging the southern horizon, then turned to the northwest, and dashed headlong toward the sun. Although a comet's mass is small, the volume of its coma is far larger than the earth. "What will happen to the comet?" Soon researchers both in Japan and overseas began paying attention to the comet. "When the comet gets close to the sun, it will split into two by the effect of tidal force," one astronomer said. Another observer claimed, "the sun's heat will melt the comet completely and evaporate it."
The sun's surface temperature is more than 6000 degrees C and the temperature of corona reaches 1 million degrees C. Therefore, the comet will be struck by unimaginable amounts of heat from the sun. One meteorologist opined, "Guessing from the past examples, a collision of the comet with the sun will cause an explosion and it will seriously affect the temperature on the earth."

    In the midst of differing theories, Comet Seki-Lines was plunging toward the sun. Computers in the U.S. estimated the impact on the sun's surface to be on April 1. This means that in two months an incredible phenomenon is going to take place.

The great comet's collision with the sun!
Comet Seki-Lines plunging into the sun?

    The possible collision of this comet with the sun was reported widely throughout Japan by media and I have received many enquiries from all over the country. Out of curiosity and anxiety many asked what would happen at the impact. The opinion among Japanese comet specialists was clearly divided into two. One camp claimed that the comet would break up and disappear as it approached the sun. The opposing side said that it would get very close to the sun and provide a magnificent sight rivaling Halley's Comet. Personally, I hoped the second prediction would eventuate. After all, this comet was the fruits of my hard work and efforts and I didnft want it to disappear so easily. I wish it could travel to the far reaches of the solar system safely. On the other hand, the comet's very close approach to the sun will bring about valuable information in the study of astronomy. The question was if the material composing the comet could withstand the sun's extreme heat which exceeds 6000-degrees C. The answer to this question could reveal the nature of cometary material or its composition. However, "hitting the sun with a huge comet" would not be something we could experiment with on the earth.

    There seems to be no decisive theory on the composition of the comet. However, it has been proved by spectroscopic studies that most of the cometary material consists of rare gases. It involves the dispersion of light from the comet into seven constituent colors of rainbow using a kind of prism mounted on a telescope.
The cometary material is analyzed by studying these colors and absorption lines.
There is other evidence that the comet is an extremely small gaseous body. For example, while the comet is in motion, it often occults a star in the background. However, the brightness of the star hardly changes during occultation.

    The great comet of March 1744 radiated searchlight-like six tails upright over the horizon and stars were said to be clearly seen through the comet's fan-shaped tails. In March 1976 Comet West appeared at an identical position showing three beautiful tails. At its 1910 apparition, Halley's Comet came into contact with the earth. The earth passed through the comet's gigantic tail, but nothing happened to the earth atmosphere. The comet's nucleus is said to be an aggregate of numerous rock-like solid bodies and normally remains in a frozen state. When the comet gets pulled toward the sun by its gravitation, the nucleus is heated tremendously by the sun's intense light. As a result, evaporation takes place. The pressure of photons and the solar wind make the gas stream trail behind the head of the comet.

    The amount of heat the comet receives from the sun is inversely proportional to the square of the distance, but the brightness of the comet is inversely proportional to the 4th or 6th power of the distance. Therefore, even if a comet is faint at the time of discovery, it often astonishes the public by increasing its size and driving out a magnificent tail, as it gradually approaches the sun.

    Comet Seki-Lines was a very faint comet when I found it. Its diameter was only 5' (one 6th of the moon's apparent diameter). It was a relatively small body and its actual size was only several times that of the earth. However, when the orbit was calculated, it turned out that the comet would graze the sun. Theorists knew even then that Comet Seki-Lines would increase its size several thousand times on its approach to the sun and that it would become unimaginably bright.

    Astronomical organizations both in Japan and overseas had been busily making predictions. For example, Japanese Astronomical Study Association headquartered in Kanagawa Prefecture predicted the magnitude of the comet to be -7 close to the sun. Magnitude -7 rivals the brightness of half moon and it is easy to imagine how bright the comet would be. According to the most reliable predictions by Dr. Cunningham at Leuschner Observatory, California, the comet would graze the far side of the sun on April 1 that year and look enormous in the evening sky around April 4. But an unimaginable event such as the disintegration of the comet and subsequent evaporation could occur. Even if it could avoid contact with the sun, it would certainly be exposed to the sun's enormous heat. It would be an incredible phenomenon. With the comet's closest approach to the sun only days away, observatories all over the world were working hard to prepare for the spectacle of the century. Mr. Koichi Ike and I joined the excitement by setting up an observing site at the summit of Washioyama Mountain, towering high along the shore of Tosa Bay, south of Kochi City.

Copyright (C) 2007 Tsutomu Seki.