PS COLUMN ARCHIVE

February 25, 2009

Have you seen Comet Lulin?

Do you know the comet by the name of Comet Lulin? The name Lulin is originated from the astronomical observatory called Lulin in Taiwan. The Comet was found from the images taken by Mr. Lin Chi-Cheng of the observatory by using the telescope of 16 inches aperture on July 11 last year. But who actuary discovered the Comet among many star images was Mr. Ye Quanzhi, a 19-year-old student at National Sun Yat-sen University, who is working at the observatory. The later consecutive observations of the Comet revealed that it might be the first comet mankind had ever seen or might be a celestial body the future generations would come across again. As eccentricity of an elliptical orbit is extremely close to one, it is very hard to determine even returning cycle because of its long period movement. I suppose Mr. Ye Quanzhi must have been very pleased to find such Comet.

This Comet made a closest approach to the earth yesterday on February 24. The closest, and yet its distance was 0.41 AU (Astronomical Unit: approximately 60 million kilometers); it was expected that the Comet would shine as bright as a fifth magnitude star. I wanted to see the Comet by binoculars but it had been raining in Tokyo area all through to the evening yesterday; unfortunately the sky will be covered by thick clouds tonight too, not really well for star watching. All I can do is to pray for weather’s getting better as soon as possible. The Comet could be hopefully observable by binoculars until the beginning of next month. After the middle of March the Comet will be moving away both from earth and sun to make it rapidly darkened. So, watching chance is just now. National Astronomical Observatory is campaigning “Can you see Comet Lulin?” and so how about tying a comet watching to report them of your observation results.

http://www.nao.ac.jp/phenomena/20090220/index.html

Now astronomical news is busy with this Comet Lulin; not only its news value but also such a long period comet is a very interesting subject to study from scientific point of view. Generally speaking, a comet evaporates ice as watery vapor and emits various volatile gasses and dusts, because it is so much parched by the sun as it’s getting closer. Therefore, the comets like Halley’s comet (short period comet) that have approached the sun a number of times in past are so much parched up by sun that raw materials originally possessed by the comet at the time of its birth have been substantially lost. In the case of Comet Lulin, however, it has accessed the sun comparatively fewer times so that the possibility is very high for its reserving raw materials as they were at the time of its birth. Therefore, by carefully studying the substances emitted from the comet at its access to the sun, we can obtain information about molecules that produced the comet so as to make it possible to presume how those comets were created under what kind of circumstances at the time of early solar nebula. Those observation data has not been officially disclosed yet, but we may be able to obtain the clue to clear mystery of the comet’s birth.

Please send your comments, if any, to pscolumn@planetary.or.jp

Copyright (c) 2000 The Planetary Society of Japan. All rights reserved