发信人: EPS.bbs@crux.chem.nsysu.edu.tw (观测如作战), 看板: astronomy
标  题: Re: 请问北极星
发信站: 中山南十字BBS站 (Sat Apr 12 08:10:37 2003)
转信站: Lion!news.nsysu!crux
Origin: crux.chem.nsysu.edu.tw

【 在 supernova.bbs@bbs.ntu.edu.tw (∫思念dt=爱恋+C) 的大作中提到: 】
:  Well, anyway, I have a question about this tile.
:  Although we know that the Sirius, now is not the "pole star".
:  (the nearest star to the north celestial pole)
:  is there any probability that in the future, the sirius will become
:  the "pole star" ?
:  Because you know that due to the precession of the earth, the Vega,
:  will become the "pole star" in several tens thousand years later.
:  So, EPS, do you know that is it possible that Sirius could become the pole
:  star in the future ? I don't know actually. If it is not possible,
:  could you give me a reason ? thank you very much. (due to the large
:  inclination angle of the Canis Major ? )

这问题有意思,N年後织女星会变成北极星,那麽,位於天球南半球的
天狼星在M年後会不会变成南极星? (当然现在它不是)

那就要看它在不在天球南极的进动轨道上了.

猜一下的话,织女星赤纬约40度,可以最後逛到天北极去,天狼星赤纬只有
20度不到,要逛到天南极去....应该不可能. 地轴在天球上的进动轨道是
半径23.5度的圆,所以只有赤纬大於90-23.5*2=43度的有机会成为极星而已.


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