YM COLUMN ARCHIVE

May 13, 2009

How about watching Saturn once in a while?
-----Now is the best time. -----

We can see Saturn toward direction of “the Lion” now. Some of you may have a difficulty in finding it. First, please find Triones, and then try to trace along the long curved shaft of ladle on a boldly extended line, that’s where you will see a fairly bright star of the first magnitude. It’s a yellowish star. This is what used to be called “wheat star” in Japan from time past, i.e. Arcturus of constellation Bootes. You throw a ball from the shaft of Triones to make it bounced on Arcturus, around which grounding area is a bright star without blinking. This is Saturn. Although the Lion also has a bright star of the first magnitude called “Regulus”, Saturn now is brighter than Regulus, so I think you can’t miss it.

http://www.astroarts.co.jp/special/2009saturn/index-j.shtml

On last March 10, Saturn became positioned direct opposite of sun as viewed from earth. This is what is called “opposition”. Because Saturn is, at this time of opposition, located opposite to sun, it rises from east at sunset to be culminated at midnight and then setting in the western sky at sunrise. As time goes by, timing of Saturn’s rise and its culmination moves earlier little by little, therefore it is the best time now to watch Saturn from the earth. Furthermore, interestingly enough, the chance of observing Saturn right from the side is approaching (Aug. 11 and Sept. 14) so that you can see Saturn with almost no rings by astronomical telescope.

Beautiful rings of Saturn disappear every fifteen years, which does not necessarily mean that the rings physically vanish. The width of Saturn rings range several ten thousand kilometers but only a few hundred meters wide at most when viewed from the side to make it appear as if rigs vanished.

Because the inclination of Saturn as viewed from earth changes every 29.5 years like a period of revolution, appearance of rings vanishing occurs twice during this period, i.e. once in 15 years.

http://www.astroarts.co.jp/special/2008saturn/index-j.shtml#disappearing

Now is its time. It takes another 15 years to see such Saturn, so why not try to look at it? Incidentally, when Galileo Galilei took a telescope toward night sky to watch Saturn for the first time in the world 400 years ago, he could not observe the rings clearly due to low-end telescope and so he left his memorandum, “Saturn has ears”.

I welcome your opinions on this column to the following E-mail address.
matogawa@planetary.or.jp

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